ADAPTATIONS, GENETIC VARIATION AND NATURAL SELECTION
Seventh Grade
Piloted at West Hawaii Explorations Academy (WHEA)
By: Leayne Patch-Highfill and Jessica Schwarz
PRISM UHH GK-12 Program ADAPTATIONS, GENETIC VARIATION AND NATURAL SELECTION
GRADE LEVEL: Seventh Grade
PURPOSE: This curriculum was designed to communicate concepts about evolutionary processes to seventh grade students. Hawaii is home to many endemic species that exhibit different genetic variations. These unique species are excellent examples to utilize to help students understand evolution.
STANDARDS/BENCHMARKS: Standard 1: The Scientific Process: SCIENTIFIC INVESTIGATION: Discover, invent, and investigate using the skills necessary to engage in the scientific process Benchmark SC.7.1.1 Design and safely conduct a scientific investigation to answer a question or test a hypothesis Benchmark SC.7.1.2 Explain the importance of replicable trials Benchmark SC.7.1.3 Explain the need to revise conclusions and explanations based on new scientific evidence
Standard 3: Life and Environmental Sciences: ORGANISMS AND THE ENVIRONMENT: Understand the unity, diversity, and interrelationships of organisms, including their relationship to cycles of matter and energy in the environment Benchmark SC.7.3.2 Explain the interaction and dependence of organisms on one another
Standard 5: Life and Environmental Sciences: DIVERSITY, GENETICS, AND EVOLUTION: Understand genetics and biological evolution and their impact on the unity and diversity of organisms Benchmark SC.7.5.2 Describe how an inherited trait can be determined by one or more genes which are found on chromosomes Benchmark SC.7.5.3 Explain that small differences between parents and offspring could produce descendants that look very different from their ancestors Benchmark SC.7.5.4 Analyze how organisms' body structures contribute to their ability to survive and reproduce Benchmark SC.7.5.6 Explain why variation(s) in a species' gene pool contributes to its survival in a constantly changing environment
RATIONALE: The Hawaiian Island chain is the most isolated archipelago on the planet. This isolation has limited the number of animal and plant species that have arrived here naturally. When organisms do colonize the islands successfully, their populations must change over time in order to suit the conditions of their new environment. As a result of millions of years of evolution in isolation, the Hawaiian Islands are home to many fascinating endemic species, such as Hawaiian honeycreepers, Happy-face spiders, and Ohia trees. This curriculum focuses on examples of Hawaii’s native flora and fauna to understand evolutionary concepts, including genetic variation, natural selection, and adaptation.
Additional reading material developed by Full Option Science System (FOSS) at the Lawrence Hall of Science is included for each topic. Background information is included at the beginning of each lesson, but more detailed information with added examples from FOSS is included for added teacher support. This unit can be used as supplemental teaching materials with the FOSS Populations and Ecosystems Course, lessons Adaptations, Genetic Variation and Natural Selection.
LESSONS PLAN: This unit was designed to last from 8-9 weeks, depending on the total number of field trips taken or how long it takes to complete “Build a Hawaiian Bird”. Most lessons can be completed within a 45-minute class period, but some lessons need several weeks to be completed. Lessons that include a field trip take the entire school day. Depending on the number of science classes taught each week, the duration of this unit will vary. Due to complex topics, students may need extra time to review concepts before starting lessons, which will also affect the duration of this unit. Although the topics are introduced in a particular order and the unit is designed to flow well, the lessons can be used out of context or used individually to address specific concepts. All lesson plans start with a summary of the lesson and a list of objectives students will learn. Lessons also include detailed materials lists as well as instructions for teacher preparation at the beginning of each lesson. The instructor should scan these lists prior to beginning of each lesson since materials must be purchased (some ordered), hand-outs should be Xeroxed, and field trips must be organized. Background information is also included with each lesson for the instructor and vocabulary words that can be used for vocabulary or spelling lessons are introduced here as well.
Week 1: Students are introduced to the concepts of adaptations, (founder species, endemism, adaptive radiation, Hawaiian honeycreepers, Hawaii as an archipelago, etc.) and a verbal pre-assessment of what the students already know about the topic is conducted. Students can be given background information on Adaptations before the start of the first lesson and this could also be discussed. The students then learn about particular adaptations Hawaiian birds have in order to survive and study a poster of different bird bills. They then engage in a hands-on Hawaiian Bird Beak Adaptation Lab to simulate how birds have particular beak shapes to acquire different food sources.
Week 2: If applicable, students will explore different bird habitats on a field trip. In this unit, students visited Puu waa waa Forest Bird Sanctuary. Other ideas for field trips could be Hawaii Volcanoes National Park, Kaloko-Honokohau National Park or Kipuka 21 on Saddle Road. Students will observe different adaptations birds have in order to survive in their respective habitat. If a field trip is not possible, a classroom simulation of a bird habitat could be created. After the field trip, students will write a paper about a Native Hawaiian Forest Bird.
Week 3-4 (could last to week 5): Students get creative and apply what they have learned in prior weeks with “Build a Hawaiian Bird”. They first develop a bird from paper cut- outs provided. After the model is completed, the bird is then constructed using papier mache. The actual building of the birds can take several weeks depending how detailed the birds become. After the birds are completed, students write a paper describing their bird and its specific adaptations. Each bird should also be presented to the class.
Week 5: Students are introduced to the subject of Genetic Variation. Genetics can be a confusing concept for students, having students read the background material provided helps with complex vocabulary. After discussing the reading material, students play Vocabulary Bingo to get more comfortable with the topic. If more review is needed, a vocabulary review is also provided. Students then study human traits in the lesson, “Exploring Human Traits” where they survey their own traits.
Week 6: Students will learn how genes are passed from generation to the next by studying Happy-Face Spiders. They will act as captive breeders and choose traits to breed that are beneficial for survival. Punnet squares will also be introduced.
Week 7: After students have a solid understanding of adaptations and genetic variation they are introduced to the topic of Natural Selection. They participate in a natural selection simulation in which they create and modify “paper airplanes” over several generations to see how favorable heritable traits are passed on.
Week 8: Students get another chance to get out of the classroom with a field trip to the Ohia Common Garden in Volcano. Ohia from different elevations have morphological differences and students get a chance to observe this phenomenon. After the trip to the garden, students write a reflection about their field trip.
CONCEPT MAP:
FORMATIVE ASSESSMENT: The level at which the students understand the topic will assessed throughout the lessons. Each lesson will begin by asking the students what they already know or recall about the topic. At the end of each lesson the students are asked to come up with three concepts they learned during the lesson. At the beginning of the next lesson the previously learned concepts will be re-visited. After the Hawaiian Bird Beak Adaptation lab, students will take a field trip to different bird habitats to see how birds use their adaptations in the wild. After this field trip, students write a scientific report on a Hawaiian bird of their choice. Students will be given background reading material on genetic variation for homework in order to discuss the topic. The next lesson will begin answering questions about the reading material and vocabulary will be assessed with vocabulary bingo. Prior to visiting the Ohia Common Garden, the students will be introduced the concept of Natural Selection by talking about Ohia and phenotypic plasticity. Before meeting with the guest speakers, students were able to ask questions to clear up any misconceptions. The students will then write a reflection about their visit to the garden.
SUMMATIVE ASSESSMENT: These students will not have one final assessment project; rather they will have summative assessments at the end of each topic. They will be assessed of their knowledge of adaptations with the activity “Build a Hawaiian Bird”. They choose adaptations that will be beneficial for the birds’ survival and reproduction. Students follow with written reports explaining the scientific name given to the birds, the adaptive advantages of their features, and how the birds are adapted to their environments. Finally, students improve their communication skills by giving oral presentations on their project. After learning about genetic variation of Happy-face spiders, students will choose the color of spider they would use to breed so the spider can survive in the wild. They then color a picture of a Happy-face spider using the colors they chose to breed. They will continue to improve on communication by presenting their pictures to the class and defending their selection. Finally, after studying natural selection, the student will write a reflection about their trip to the Ohia Common Garden and Hawaii Volcanoes National Park.
This unit was developed and piloted by Leayne Patch-Highfill and Jessica Schwarz at West Hawaii Explorations Academy (WHEA).
PRISM UHH GK-12 Hawaiian Bird Beak Adaptation Lab ADAPTATIONS Summary Students will be introduced to the different types of bird beaks that Hawaiian Concepts Kkjkjkj birds have developed as adaptations to the different habitats in which they live. Endemic Haw aiian They will use tools that represent different beaks to learn which beak is better birds are unique to adapted to collect different food types in a certain amount of time. Hawaii becaus e they are only found here. Objectives Founder spec ies that • Students will examine the relationship between a bird’s beak and its came to Hawa ii were ability to find food and survive in a particular habitat. isolated for m illions of • They will understand that Hawaiian birds have adapted physically to years, and the y had to their food sources. physically ada pt in • Students will learn about different Hawaiian birds. order to survi ve in • Students will explore which beaks are more efficient for collecting foods their new by experimenting with different tools representing different beak types. environments . Many • Students will represent their data using bar graphs. Hawaiian birds , such • Students will recognize the importance of multiple trials. as Hawaiian honeycreeper s have Materials different beak length Plastic cups to represent bird stomach-will need one for each student and sizes in or der to Beak materials: obtain food in their 5-6 sets of chopsticks, 1 turkey baster, 1 nut cracker, 2 pliers, 4 tweezers, 2 habitats. medicine droppers, 1 Clothes pin, 2 rulers, 3 plastic spoons, 1 slotted spoon,1 long snapping hair clip, 1 small hand strainer, and 3-4 straws to hold Standards ad dressed marshmallows and one straw for nectar 7.1.1, 7.1.2, 7 .5.4 Food Materials: Gummy worms, sunflower seeds, rice, small berries or sweet tart candies, Duration marshmallows, Swedish gummy fish, oreo/graham cracker cookie crumbs (to 60 minutes represent soil), small twigs, water colored with food dye (can use clear if easier). Three plastic graduated cylinders Vocabulary 2 Cookie Sheets or pans for sunflower seeds and rice Endemic Plastic container to hold “soil” and worms Founder spec ies Bowls for holding water Hawaiian Pictures of Birds honeycreeper s Bird Beaks Record Sheet (see below) Adaptive rad iation Challenge cards for each station (see below)
Source Mate rial Teacher Prep for Activity Adapted from • Make challenge cards (cut and paste from list below) to put at each sciencenetlinks .com & station-can be made on card stock and laminated, so they can used again. www.eduref.or g The challenge cards state the scenario for each station. • Xerox “Adaptations” reading and data sheet provided • Set up 8 work stations: 1 for each type of food source represented. Place the 3 different types of tools for each station. Station #1: Bird: Ae’o Food Source: Gummy worms buried in cookie crumbs Tools: chopsticks, turkey baster, nut cracker Station #2: Bird: Palila Food Source: String beans and sunflower seeds scattered on cookie sheet Tools: pliers, chopsticks, tweezers
Station #3: Bird: I’iwi Food Source: Colored water in a graduated cylinder (one for each student) Tools: Medicine dropper, straw (don’t suck up, use finger to stop the liquid), pliers Station #4: Bird: Elepaio Food Source: Rice spread out on cookie sheet (to represent insects) Tools: Tweezers, clothes pin, medicine dropper Station #5: Bird: Nene Food Source: Small berries and grass (round sweet tarts work well too) G gh Tools: 2 rulers held together, chopsticks, spoon Station #6: Bird: Albatross Food Source: Swedish gummy fish Tools: Chopsticks, long snapping hair clip, spoon Station #7: Bird: Koloa or Hawaiian Duck Food Source: Small twigs in a bowl of water Tools: Slotted spoon, tweezers, hand strainer Station #8: Bird: ‘Io or Hawaiian Hawk Food Source: Marshmallows (skewered on a straw) Tools: Chopsticks, tweezers, spoon
• Place each challenge card and picture of corresponding bird at every station Background Over time, ani mals change in order to fit the needs of their environment. The Hawaiian Islands are the most isolated archipe lago on the planet, and due to millions of years of isolation, only a small amount of animals and plants have ar rived here. Species arrived on the islands by only three modes of transportation: wind, waves, and wings (the “thr ee Ws”). All plant and animal species that are native or endemic to Hawaii descended from a small communi ty of founder species. Hawaiian rain forests are home to several endemic species, such as Hawaiian birds and these species are unique to the islands. Most endemic forest birds belong to a group of birds known as Haw aiian honeycreepers. Scientists think all the honeycreepers evolved from a single finch species that colonized the islands 15 million years ago. Hawaiian endemic birds evolved and radiated into new species after they arri ved to the islands from somewhere else. This is a process called adaptive radiation, which has resulted in ma ny different honeycreepers adapted to various environments. One characteristic that can distinguish Hawaiian hone ycreepers apart are their diverse bill shapes and lengths. There are also non-honeycreepers, such as a species of F lycatcher (the Elepaio) and a species of Hawk (the ‘Io) that are also endemic to Hawaii. All birds have different beak shapes and sizes depending on what the bird eats and where that food is found. A bird’s beak is basically a lightweight, bony extension of the skull. Bird beaks are multi-functional tools used to gather and capt ure food, build nests, groom feathers and attack competitors. Procedure 1) First have s tudents read background information about Adaptations (Information follows)-this can be done in class or have students read the information for homework or the instructor can lecture on the material. 2). After stude nts have completed the readings, ask the students what they know about adaptations. Explain that Hawaii is the most isolated archipelago in the world and how animal and plant species arrived here. Be sure the students unde rstand species, such as Hawaiian honeycreepers filled different niches throughout Hawaii and adapted to the ir specialized habitats. Have them explain what it means if a species is endemic or indigenous. Pick at least three c oncepts that you will want the students to really remember such as; What is adaptive radiation? What will happe n if a species will not adapt to environment? or What will happen if a habitat changes? 3). Divide stude nts into groups of three (one tool per student). If there are more students, add another station, or divide groups into four and have one of the students be responsible for timing the other students and writing down data. Have the students repeat what they did, but have the student who was the scorekeeper trade out with another student. Also, each student will keep the same beak throughout the lab. They should improve as they go along. 4). Have stude nts go to their assigned station and have them read their challenge card. 5). Pass out re cord sheet.
6). Have each student write down a prediction on the worksheet provided. 7). Each student will be given 20 seconds to gather as much food as they can with the “beak” (tool) they have. They will put the food into their “stomach” (cup). 8). When ftfhef teacher says “Stop”, students empty their stomachs and count the number of items they collected. Record this amount on the Bird Beaks Record Sheet. 9). Repeat the trial 3 times and be sure students empty their stomachs after each round and record amount on their w orksheet. 10). Stude nts calculate the average amounts for each beak type and have each group construct a bar graph of t heir averages for each station. The three different bird beaks should be on the X axis and the average am ount of food collected should be on the Y axis. (See sample bar graph below).
Amount of Food
Beak 1 Beak 2 Beak 3
Teacher R esources for this activity Challenge Cards: Challenge #1-You have been given gummy worms (to represent worms) as your food source. You have also been given sample beaks: 1) Chopsticks, 2) Turkey Baster, and 3) Nut cracker. Your challenge is to obtain as m any gummy worms as you can that are buried in the soil within 20 seconds. Put your food in your stom ach (cup). Repeat each trial 3 times and record the amount of food after each trial on your worksheet . Challenge #2-Your have been given sunflower seeds (to represent seeds) as your food source. You have also been given sample beaks: 1)Pliers, 2) Chopsticks, and 3) Tweezers. Your challenge is to use each beak to cr ack the shell and remove the seed inside within 20 seconds. Put your food in your stomach (cup). Repe at each trial 3 times and record the amount of food after each trial on your worksheet. Challenge #3-You have been given colored water (to represent nectar) in a graduated cylinder. You have also been given sample beaks: 1) Medicine dropper, 2) Straw, and 3) Pliers. Your challenge is use each beak to se e how much water you can transfer to your stomach in 20 seconds. Repeat each trial 3 times and record the amount of food after each trial on your worksheet. Challenge #4-You have been given rice (to represent insects) as your food source. You have also been given sam ple beaks: 1) Tweezers, 2) Clothes Pin, and 3) Medicine Dropper. Your challenge is to use each beak and transfer as many pieces of rice to your stomach in 20 seconds. Repeat each trial 3 times and record the amount of food after each trial on your worksheet. Challenge #5-You have been given small berries or sweet tart candies that llok like berries as your food source. Y ou have also been given sample beaks: 1) 2 rulers held together, 2) Chopsticks, and 3) Spoon. Your chal lenge is to use each beak and transfer as many berries to your stomach in 20 seconds. Repeat each trial 3 times and record the amount of food after each trial on your worksheet. Challenge #6-You have been given Swedish gummy fish (to represent fish) as your food source. You have also been given sample beaks: 1) Chopsticks, 2) Long snapping hair clip, and 3) spoon. Your challenge is to use each beak and transfer as many fish to your stomach in 20 seconds. Repeat each trial 3 times and record the amount of food after each trial on your worksheet.
Challenge #7-You have been given small twigs (to represent small invertebrates) in water as your food source. You have also been given sample beaks: 1) Slotted spoon, 2) Tweezers, and 3) Small hand strainer. Your challenge is to use each beak and transfer as many twigs to your stomach in 20 seconds. Repeat ea ch trial 3 times and record the amount of food after each trial on your worksheet. Challenge #8-You have been given Marshmallows on a straw (to represent small mammal) as your food source. Y ou have also been given sample beaks: 1) Chopsticks, 2) Tweezers, and 3) Spoon. Your challenge Kisl ;br eak apart the marshmallows and transfer as many marshmallows to your stomach in 20 seconds. R epeat each trial 3 times and record the amount of food after each trial on your worksheet.
Assessme nts Journal w riting Bird Beak Data Sheet Build a H awaiian Bird Lesson
Extension s If time pre vails, students can switch stations after the first 3 trials and learn about different beak adaptations . If this is the case, then the worksheet should be extended to add more columns.
Also, take students on a field trip to different habitats where native birds might be found. For example, students c ould visit a rain forest such as Volcanoes National Park to see native birds such as the ‘Omao, Apapane a nd Hawaii Amakihi. Students could also visit a mesic forest like Pu’u Wa’a Wa’a Forest Bird Sanctuary and observe birds like Akepa and Elepaio and in the Dry Land Forest of Pu’u Wa’a Wa’a students m ay see Nene. If time prevails, take students on another field trip to a habitat that is completely different f rom the first one they visited. A second field trip could be to the coastline, such as Kaloko- Honokoha u National Historical Park for example. Students may see Ae’o and the Hawaiian Coot. It would be ideal if students had binoculars and field guides to see the birds up close. Discuss with students why birds live in different habitats (be sure to notice different food sources within each habitat). Ask what adapt ations the birds have in order to survive in each of the habitats. This would be a good time to get the stude nts thinking about what types of questions they could ask in order to conduct a scientific investigat ion in the feild. For example, “How many invertebrates does an Ae’o collect in a certain amount of time”? How would they set that experiment up and how would they conduct it? They can write about it in a journal entry. If a field t rip is not possible, create a class simulation of a field trip. Before the students come to class, transform your classroom into a natural habitat. Get pictures of birds and plants that represent a particular habitat and hang on wall or an area of your choice. When the students come to class, explain to them which habi tat they just encountered and have them walk around to see the different bird and plant pictures. Audio with bird songs could help improve this simulation. For ideas about forest habitats, the following website is a good start (pgs 7-11): http://www .state.hi.us/dlnr/dofaw/kids/teach/forest%20activity%20guide.pdf They can still use field guides and come up with questions that would be suitable for field research.
Great field guides to use as references on bird watching and plant identification are: A pocket guide to Hawaii’s birds, H.D. Pratt and J. Jeffrey (~$9.00) A pocket guide to Hawaii’s trees and shrubs, H.D. Pratt (~$10.00)
Resource s http://www .eduref.org/cgi-bin/printlessons.cgi/Virtual/Lessons/Science/Animals/ANM0016.html www.scie ncenetlinks.com/pdfs/birdbeaks_actsheet.pdf http://www .hear.org/hoike/ http://www.esi.utexas.edu/outreach/gk12/docs/lessons/birdBeak.pdf Foss-Populations and Ecosystems
Bird Beaks Record Sheet
ll Name:______
My Food Source is ______.
My Bird is ______.
Prediction: I think that ______
______
______
Data Table
Beak 1: Beak 2: Beak 3:
rere
Tr ial 1
Tr ial 2
Tr ial 3
Ave rage (T otal/3)
Draw a bar graph that shows the average amount of food gathered by the three types of beaks.
Amount of Food
Beak 1 Beak 2 Beak 3 A e `o
Photo: en.wikipedia.org/wiki/RecAurvirostridae
Hawaiian Black-necked Stilt P a l i l a
Photo: J. Jeffrey `I `i w i
Photo: J. Jeffrey `E l e p a i o
Photo: P. Latourrette N e n e
Photo: www.americanparknetwork.com
Hawaiian Goose M o l i
Photo: www.pbase.com/jpkln/image/54126096
Laysan Albatross K o l o a
Hawaiian Duck `I o
Photo: R. Decker Hawaiian Hawk Challenge # 1-You have been given gummy worms (to represent worms) as your food source. You have also been given sample beaks: 1) Chopsticks, 2) Turkey Baster, and 3) Nut cracker. Your challenge is to obtain as many gummy worms as you can that are buried in the soil within 20 seconds. Put your food in your stomach (cup). Repeat each trial 3 times and record the amount of food after each trial on your worksheet.
Challenge #2-Your have been given sunflower seeds (to represent seeds) as your food source. You have also been given sample beaks: l)Pliers, 2) Chopsticks, and 3) Tweezers. Your challenge is to use each beak to crack the shell and remove the seed inside within 20 seconds. Put your food in your stomach (cup). Repeat each trial 3 times and record the amount of food after each trial on your worksheet.
Challenge #5-You have been given small berries as your food source. You have also been given sample beaks: 1) 2 rulers held together, 2) Chopsticks, and 3) Spoon. Your challenge is to use each beak and transfer as many berries to your stomach in 20 seconds. Repeat each trial 3 times and record the amount of food after each trial on your worksheet.
Challenge #6-You have been given Swedish gummy fish (to represent fish) as your food source. You have also been given sample beaks: 1) Chopsticks, 2) Long snapping hair clip, and 3) spoon. Your challenge is to use each beak and transfer as many fish to your stomach in 20 seconds. Repeat each trial 3 times and record the amount of food after each trial on your worksheet.
Extensions Take students on a field trip to different habitats where native birds might be found. Students can observe birds in the wild and they can also record what birds they will see in different environments. For example, if you live on the Big Island, students could visit a rain forest such as Volcanoes National Park to see native birds such as the ‘Omao, Apapane and Hawaii Amakihi. Students could also visit a mesic forest like Pu’u Wa’a Wa’a Forest Bird Sanctuary and observe birds like Akepa and Elepaio and in the Dry Land Forest of Pu’u Wa’a Wa’a students may see Nene. If time prevails, take students on another field trip to a habitat that is completely different from the first one they visited. A second field trip (on the Big Island) could be to the coastline, such as Kaloko-Honokohau National Historical Park for example. Students may see Ae’o and the Hawaiian Coot. It would be ideal if students had binoculars and field guides to see the birds up close. If you live on neighboring islands, bird habitats are accessible as well. On Maui, native forest birds can be found at Hosmer Grove in HaIeakala National Park and water birds can be found at Kealia National Wildlife Refuge. On Oahu, seabirds can be seen around Makapu’u Point and some native forest birds might be seen near Lyon Arboretum. On Kauai, Kokee State Park is a great place to see native forest birds and Kilauea Point National Wildlife Refuge is a great environment to see different species of seabirds and Nene. If you don’t have the opportunity to visit a habitat that has native birds, students can observe non-native birds just about anywhere. All birds use certain adaptations to survive so observing any type of bird will be beneficial. Discuss with students why birds live in different habitats (be sure to notice different food sources within each habitat). Ask what adaptations the birds have in order to survive in each of the habitats. This would be a good time to get the students thinking about what types of questions they could ask in order to conduct a scientific investigation in the field. For example, “How many invertebrates does an Ae’o collect in a certain amount of time”? How would they set that experiment up and how would they conduct it? They can write about it in a journal entry. If a field trip is not possible, create a class simulation of a field trip. Before the students come to class, transform your classroom into a natural habitat. Get pictures of birds and plants that represent a particular habitat and hang on wall or an area of your choice. When the students come to class, explain to them which habitat they just encountered and have them walk around to see the different bird and plant pictures. Audio with bird songs could help improve this simulation. For ideas about forest habitats, the following website is a good start (pgs 7-11): http://www.state.hi.us/dlnr/dofaw/kids/teach/forest%20activity%20guide.pdf They can still use field guides and come up with questions that would be suitable for field research.
Great field guides to use as references on bird watching and plant identification are: A pocket guide to Hawaii’s birds, H.D. Pratt and J. Jeffrey (~$9.00) A pocket guide to Hawaii’s trees and shrubs, H.D. Pratt (~$10.00)
Resources http://www.hawaiiaudubon.com/birding/ FOSS-Populations and Ecosystems
West Hawaii Explorations Academy Public Charter School Developing an Outline
Title: Short Description of what the paper is about.. .not Topic Paper!
Topic: Native Hawaiian Forest Birds
Major Point 1 : Description of Organism (including scientific name and significant adaptations)
Major Point 2: Description of Habitat
Major Point 3 : Description of Negativepositive Human Impact (Origin and nature of threats to organism/habitat/efforts to preserve/conserve organisrnlhabitat)
Conclusion: Summarize three main points, state opinion and importance of this topic.
Topic sentence:
Opening Paragraph:
Major Point 1 : *
Rev. 411 012007 West Hawaii Explorations Academy Public Charter School Major Point 2:
Major Point 3:
Bibliography : Must be in proper format (separated by type, alphabetized and including the necessary information) and include three sources where you found the information cited in the body. Do Not Use .corn, unless previously approved by advisor. Paper will not be accepted if this section is not completed or is incomplete.
Example of a source cited within the body of the paper: The use of enriched food will increase the growth rate of the Omilu (Vencent,1999). 0r According to Vencent (1999) the use of enriched food will increase the growth rate of Omilu. Or "During this study, the use of enriched food in the diet of Omilu resulted in a 22% increase in growth rate over a four month trial period," (Vencent, 1999).
Example of a source cited within a bibliography:
Bibliography Magazine Vencent, Amanda. 1999."Raising Omilu." National Geographic, Available at: www.national~eographicmagazine.com.
Author's last name, first name. (or name of organization) date. "Title(of article)." Title (of book or magazine). Place Published: Publisher. (or web address)
Book Vencent, Amanda. 1999. Aquaculture Techniques. Honolulu, Hi: Bess Press.
Website Vencent, Amanda. 1999. Enriching Food for Aquaculture. http//www.pbs.orgiwnetlenrichingfoodforaqua/
Rev. 411 0!2007 1, ,-
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~UBC .~RRY'J%Q~ Dr. H Douglas Pratt Iias decade6 of experlencc ?s Is a f~eldnatural~st, scholar, wildl~feartrs: ph6tor)re~ahnr.an! ecotour leader In Hawal'~Me I,: best hnown ~UIhi9 tech nlcal and popular works on Hawailall btrds duch as h13 popular gu~deboolc Enjoyrng t31rds kt ilawFta, bhwat'l Beautiful Wrds, and A Pocket F~ltdoto klitn~a~'r'sBirds.
Aloha! Welcome to the Ahupua'a of Pu'u Wa'awa'a. The Division of Forestry & Wildlife and the Pu'u Wa'awa'a Volunteer Program are pleased to offer these trails for your enjoyment. Please observe the following guidelines so that these hails not only stay open, but so that the system may expand! There is no trail maintenance staff. Please kokua to keep this trail clean and safe. If you encounter any litter, please pick it up. If you see any loose rocks on the trail surface, please toss them aside - mahalo! Dogs are allowed on the trail at this time. This is for your safety as well as your pet. We are working to expand the trail to include some areas for dogs on leashes. r Please stay on the trails as indicated on the map. Absolutely NO ENTRY into the quarry area. Keep the pedestrian gate closed at Tamaki Paddock --this area remains an active cattle ranch. Please be courteous to hikers, residents and ranchers. For more information about Pu'u Wa'awa'a and Volul~teerProgram, call 937-2501.
PRISM UHH GK-12 Build a Hawaiian Bird ADAPTA TIONS Summary After students have completed the Bird Beak Adaptation Lab and study different Concepts habitats to see how birds are adapted to different habitats in the wild, students will Different bi rd species, create imaginary birds using papier mache´. such as Haw aiian honeycreepe rs are Objectives endemic to Hawaii • Students will identify and describe the advantages of bird adaptations and and they ha ve adapted evaluate the importance of adaptations to birds. to the divers e habitats • Students consider different bird adaptations required for a specific habitat. found only awaiathiadfn gfa • Students will present their constructed bird to the class and will defend why these ecosys tems. The they chose their specific adaptations. beak structur es, leg and facial m uscles of Materials honeycreepe rs all give Paper bird parts (cut-out worksheet) insight into their diets DLNR free posters to as habitat reference and how the y forage Adaptations and advantages for bird worksheet (For teacher) for food. Elmer’s papier-mache glue (powder form) Newspaper Standards Addressed Glue, Scissors, Paint 7.1.3, 7.3.2, 7.5.4 String to display birds
Duration Teacher Prep for Activity 40-50 minut es to • Elmer’s papier-mache art paste was used for this lesson. The paste was construct pa per bird. ordered from the following website: (2) 40-50 m inute class http://www.enasco.com/ProductDetail.do?sku=8100197J, each box costs periods to c onstruct about $2.50/box and make 4 quarts. Approximately 3-4 boxes were used for papier mache bird. 15 large birds. 40-50 minut es for • Make Xerox copies of bird cut-outs and outline for Topic Paper student pres entations. • Collect newspaper • Request free bird habitat posters from DLNR: Source Mat erial http://www.state.hi.us/dlnr/dofaw/kids/teach/forest%20bird%20poster2.jpg Adapted from Project Wild Background All life forms have adaptations that allow them to survive and maintain populations. Wildlife species are adapted to the environments in which they live. Birds have many different adaptations, including beaks, feet, legs, coloration and bone type. Beaks allow different birds to acquire specific foods and their feet allow them to grasp branches or prey, or wade in water. In order for birds to be better suited to their environment, these adaptations have evolved. Many different Hawaiian forest birds have different adaptations that allow them to survive in such a unique environment. Some forest birds are known as honeycreepers and many of the honeycreepers have beaks that are shaped in order to gather food from specialized sources. For example, the ‘I’iwi has a long, curved bill that is designed to consume nectar from long, tubular, curved flowers. Also, the Palila, another honeycreeper, has a short, thick bill used to rip open mamame pods to obtain the mamane seeds inside. The `Io or Hawaiian Hawk has talons in order to grasp food items such as small birds and a sharp bill to eat its prey. The ‘Ae’o or Hawaiian Stilt has long legs so it can wade in mudflats or shallow coastal wetlands. The way that a bird looks, obtains food, or travels are all advantages for a species to physically adapt to its environment.
Procedure 1).Discuss w ith students the different adaptations that bird’s exhibit-explain the different adaptation paper cut- outs that wi ll be given to the students and the benefits of these adaptations. Students could also help with what cut-outs wil l be used. Days prior to this starting this activity ask the students to brainstorm about different adaptations that they may have already learned from the previous lessons or bring in pictures of birds. A worksheet w ith bird cut out will be provided, but the class could make other cut-outs. Each student should create their own bird using the paper cut-outs, but student’s can pair up to create a single bird. Our students worked toge ther in pairs and integrated their different adaptations to create one bird. (Examples are included at the end of the lesson. We learned that the larger the size of the balloon used for the body form, the larger the bird.) 2). The teac her can either assign a specific habitat that the student will create the bird for or the students can choose the ha bitat themselves. For this lesson, the habitats will be the coastline and the rainforest. Students can choose adapt ations from either one of the habitats or a combination of both. Inform students that they will later have to explain in a presentation why they chose certain adaptations and the benefits for those adaptations. Explain to the students that they will have a chance to design their own original bird that is adapted to a Hawaiian habitat (e.i. rain forests, dry forests, wetlands, shoreline, etc). Each student should decide: The name of their bird (they should come up with a scientific name that is representative of their created bird) , what the bird will eat (nectar, insects, small mammals, invertebrates, etc.), how it moves (fly or non-flyer), i t’s gender (coloration), range (does it have to travel far for food), where does it nest (in the trees, ground, bur rows) and any other characteristics they may want to add. As they create their birds, they should be writing in a journal or notebook why they are choosing the specific traits since they will have to present their bird at a late r time and write a paper. An outline is provided for a paper the students will write after they have completed t heir bird. This paper should include all the information about the bird the students think is applicable. 3). Have the students choose from the cut-outs presented to them to construct a preliminary paper bird. Have the students glue their different parts to a blank piece of paper. As they are selecting the parts they are going to use, they shoul d be taking notes about why they chose the particular traits. They should also color their bird, since colora tion in birds is important adaptation for camouflage and courtship. This might take a full class period; sinc e it may take students time to decide which adaptations they will use. 4). Once the paper bird is constructed, they will then have the opportunity to create their paper bird using papier mache . This could also be done in other artistic techniques, such as drawing or clay. 5). Students will then be asked to present their bird to the class. They should include the name of their bird, its food source s, lifestyle, etc. They will have to describe why they chose the adaptations they used and the advantages provided by the adaptations for the habitat of the bird. 6). Once stude nts have presented their birds, hang them from the ceiling to display their creations.
Assessment s Designed B ird with appropriate adaptations Written pape r about their bird. Presentation
Resources Project Wild -K-12 Curriculum & Activity Guide. 2002 http://www. hear.org/hoike/ http://www. state.hi.us/dlnr/dofaw/kids/teach/index.htm http://www. state.hi.us/dlnr/dofaw/kids/teach/forest%20bird%20poster2.jpg (for free posters) FOSS-Popul ations and Ecosytems
Teacher R esources
Adaptations and advantages worksheet for teacher: Beaks: Advantage: Pouch-Like Can hold the fish it eats Long-thin Can probe in mud or shallow water for insects Pointed Can probe into bark of trees for insects, like grubs Curved Can tear solid tissue for the meat it eats Short, stout Can crack the seeds and nuts it eats Slender, long Can probe the flowers for nectar it eats
Feet: Advantage: Grasping Aids in sitting on branches, roosting, and protection Long toes Aids in walking on mud Clawed Can grasp food when hunting prey Webbed Aids in walking on mud
Legs: Advantage: Long, slende r Aids wading Powerful m uscles Aids lifting, carrying prey Long, powe rful Aids running Flexor tendons Aids in perching, grasping
Wings: Advantage: Large Aids in flying with prey, soaring while hunting
Coloration: Advantage: Bright plum age Usually male birds, attraction in courtship, mating rituals Dull plumage Usually female birds, aids in camouflage while nesting Change of pl umage- Provides camouflage protection-brown in summer, white with seasons in winter.
Bone structur e: Advantage: Fused bones Ground bird, does not fly Hollow bone s Can fly
EXAMPLES OF STUDENT WORK
Build a Bird Kit-"Cut Out" Sheets
BUILD A BIRD KIT
Body Forms To Be Used For All Birds:
Heads: ESl, Small ~nvwkkrcrcfc~
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Small insc&
Tails:
West Hawaii Explorations Academy Public Charter School Developing an Outline
Title: Short Description of what the paper is about.. .not Topic Paper!
.Topic: Forest Bird Adaptations
Introduction: introdwe main points
Major Point 1 : Description of Scientific name and reason for choosing name (Genus and species)
Major Point 2: Description of each body part and what the evolutionary purpose
Major Point 3: Explain what habitat this bird would be most successful in, give details.
Conclusion: Summarize main points Major Point 1 :
Major Point 2:
* Major Point 3: *
Rev. 4/4/2007 INVESTIGATION 8:
GOAL
Adaptatir duces students to.the conce?pt of ad; 1, any struc . an organism that ..helps it survive and reproduce.
OBJECTIVES TENT ldaptatlon is any trait of an orgarusm that enhances its chances of surviving and reproduc~ngm nvironrnt ?nt. ahue is a structure:, characteristic, or behavior of an organism, such as eye color, fur pattern, or -- -L -:-rration. lit is the w,ay a fea hue is e,cpressed in an individual organism, such as brown eyes, small spots, or r migratior1. Variation is the range...... - of expression-:--. or-<. a feature within a population, such as all the different eye colors, all the different fur patt~ems, and I all the dates on which migration starts. CONDUCTING INVESTIGATION!S Use a multimedia simulation to investigate the adaptive value of protective coloration. Conduct simulated predator/ prey interactions over multiple generations to investigate the effect of protective coloration on the color characteristics of a population of walkingsticks. BUILDING EXPLANATIONS Explain how adaptations help organisms survive in an environment. Describe how a population can change over time in response to environmental factors. SCIENTIFIC AND HISTORICAL BACKGROUND Life is incredibly robust and indomitable. ADAPTATIONS At the same time, however, it is sensitive Organisms have adaptations that allow and vulnerable. This apparent them to live in an environment. Sea otters contradiction is one of the many aspects of live in the sea, desert tortoises live in the life that makes its study so intriguing. desert, and mountain heather lives in the What makes life simultaneously durable mountains, The sea otter will die in the and fragile? desert or mountains as surely as the Life resides in individual organisms. Life tortoise and heather will die in the sea. continues as long as the basic needs of an Every kind of organism has a unique set of organism are met. These include energy, adaptations to live in its environment. water, gases, nutrients, space, and Adaptations are physiological attributes protection. The exact measure of each (structures and functions) or behaviors requirement and the medium in which it is that enhance an organism,s opportunity to provided vary for each kind of organism. live and reproduce in its environment. If the resources needed by a given The hawk's talons, the shark's broad tail, organism are plentiful--optimum the toad's long, sticky tongue, and the conditions-the organism will thrive. If clam,s hard shell are examples of the resources are marginal-just at the structural adaptations. The trout's ability threshold-the organism will survive. If to extract oxygen from water, the skunk,s any of the resources falls below the level ability to produce and spray disgusting needed by the organism, it will die. In this defensive chemicals, the beers ability to regard life is tenuous, dependent upon transform nectar into honey, and the uninterrupted access to the requirements ability to reason are examples of for life. functional adaptations. The squirrel's The resources for life originate in an propensity for storing nuts, the black organism's environment. The relationship bear's long winter hbernation, the bemeen an organism and its environment herring's habit of schooling, the crayfish's is, therefore, critically important. active territorial defense, and the arctic Environments are notoriously dynamic. tern's long annual migration are examples When an environment changes, organisms of behavioral adaptations. that interact with it are influenced. A The particular combination of adaptations change in the environment might improve expressed by an individual defines the the for a given organismto lifestyle that that organism will lead and survive. On the other hand, a change the environment in which it can survive. might decrease its survival potential. Furthermore, a change in the environment might enhance one organism's ability to survive and reproduce more offspring while it decreases the chances of another organism. VARIATION WITHIN A SPECIES BIOLOGICAL IMPLICATIONS OF VARIATION Organisms of the same kind are all members of the same species. All When the environment provides abundant members of a species have similar resources, all members of a population adaptations and, therefore, the ability to share in the bounty and survive. Optimal live in the same environment. The conditions, however, are the exception members of a species that are living rather than the rule in nature. Often some together and interacting constitute a factor in the environment is in limited population. All members of a population supply or pushing the limits of tolerance do not, however, have identical traits. of the organisms. This is where variation Within a population there is variation. is essential to the survival of the species. The individuals that have structures or Variation is the amount of difference in behaviors that allow them to break slightly physiological and/or behavioral attributes harder seeds, run a little faster, produce exhibited by the members of a population. broader leaves to capture more sunshine, Variation can show up in an organism's store a little more water, and so forth, will structures. Some giraffes, for example, have a survival advantage over other have longer necks than others. There is members of the population when the variation in neck length. Some trout have environment changes. As a result of larger, darker spots than others. There is natural variation in a population, the variation in pattern. Some sulfur population may survive failure of a butterflies are brighter yellow than others. primary food source, invasion by a fleet There is variation in color. And so it goes. predator, reduction in solar radiation, or Look at individuals in the same age class drought. It is important to note that in the species Homo sapiens and you will difierent members of the population will see a great deal of variation in size, have the advantage, depending on what strength, eye color, hair color, amount of environmental factor imposes pressure on hair, number of teeth, sensitivity to cold, the population. The result is that some and so on. members will survive to reproduce, Variation extends to behavior as well. ensuring the survival of the species and Some silk moths spin denser cocoons than the continuation of the population. others. There is variation in construction. Some red-winged blackbirds defend larger territories than others. There is variation THE ORIGIN OF VARIATION in range management. Some sunflowers One of the big ideas in biology is the bloom a few days earlier than others. origin of variation in organisms. The first There is variation in timing. Some people fully elaborated explanation of the origin- sleep later, talk louder, eat more, play more and role of adaptations in organisms was sports, or read more than others. There is by French naturalist Jean-Baptiste-Pierre- a lot of variation in human behavior. Antoine de Monet de Lamarck (1744-1829) in his book Zoological Philosophy (1809). His arguments were logical, but were Adonis. Later, he marries and settles shown later to be wrong. Even so, it is down, producing offspring in due course. important to explore his reasoning, as it Will his male progeny be husky and might also be the reasoning of some strong, reproduced in the image of their students. transformed dad? Not likely. They will have his tendency to be scrawny and In his work Lamarck proposed the victimized, just like Dad was at birth. But incorrect idea that individual organisms they will doubtless have mherited, like change in response to pressures from the hm, the adaptation for superior muscle environment in order to advance their development in response to a rigorous chances of survival. For example, Lamarck bodybuilding regimen. thought that the turtle hardens its shell in response to repeated assault by predators, In 1859, after more than 20 years of the giraffe's neck Iengthens as it reaches fieldwork and rumination on the subjects for ever-hgher foliage in the trees, the red- of adaptation, variation, and speciation, winged blackbird enhances the amount of Charles Darwin published his conclusions red on its wings to better attract a mate, called Onthe Origin of Species by Means of the poppy blooms earlier in the spring to Natural Selection, or the Preservation of take advantage of residual soil moisture, Favoured Races in the Struggle for Lijie, and a philodendron grows larger leaves to usually referred to as The Origin of Species. take advantage of the limited light filtering In it Darwin described the origin of down to the forest floor. Because these variation as a random occurrence that modifications enhanced the survival of the takes place during the process of individual, and therefore its probability of reproduction. In this way it is possible for reproduction, Lamarck proposed that the offspring to vary somewhat (or acquired characteristics were passed on to significantly) from their parents, as well as the offspring. from their siblings. Furthermore, the variation may or may not contribute to the The Lamarckian theory of evolution that improved survival of the individual grew out of this explanation of the origin sporting the variation. of adaptations was accepted for a time, but by the middle of the 19th century it had The adaptive value of a population's been refuted. Changes in structure and variation manifests itself when the behavior that occur during an organism's environment imposes pressure on the life cannot be passed to its offspring. It population. If the climate turns hot, just doesn't work that way. But students rabbits with thinner fur will dissipate heat often think this way, so it is important to better than rabbits with thicker fur. Thin understand why this is incorrect. fur in this case is a trait that gives an advantage. On the flip side, if the climate Here's an example. The 95-lb. weakling turns cold, thick fur is an advantageous grows weary of having sand kicked in his trait, and thin fur is a liability. If the face every time he goes to the beach. He climate remains unchanged, fur thickness enrolls in a bodybuilding program and offers neither advantage nor bulks up to be a magnificent 210-pound disadvantage-it is just a variation. If the climate does make a permanent shift Students will be challenged by ths idea to cold, those rabbits that randomly that organisms don't decide how to happened to have thicker fur will survive modify their structures and behaviors to better, and, in the long run, they will their advantage. They will be tempted to reproduce more. As a result of the adopt the logic that seduced Lamarck. It is differential reproduction, the population doubly difficult because the most will in time have thicker fur. The thicker important adaptive characteristic of fur is an adaptation. The important thing humans is the evolution of the brain as a to remember is that no rabbit decided to flexible, logical, problem-solving organ. have thicker or thinner fur-fur variation Because brain power is such a powerful already existed in the population, it just adaptation, humans have been extremely happened. The environment imposed successful organisms on Earth. One pressure on the rabbits, selecting those manifestation of brain power is that Homo with thicker fur to survive and reproduce. sapiens can consciously modify themselves and their environment, effectively The rock ptarmigan is a small member of changing their defensive strategies, the grouse family adapted to live in arctic modifying their body covering, moving regions year-round. It feeds and nests on faster, communicating effectively, and the ground in small family groups. securing food in many different ways. During the fall it molts its brown summer Humans are adaptable, but this must not be plumage and grows a fresh set of white misunderstood as adapted. These changes feathers and a dense downy underlayer and behaviors do not get passed down to for winter. The color and insulation the next generation, only the brain power permit the small bird to survive in the to think them up gets passed on. bitter arctic winter environment. In the spring the ptarmigan again molts, restoring its lightweight, brown summer ADAPTATIONS FOR SURVIVAL plumage. This elaborate process of feather One of the popular terms extracted from replacement could be construed as a Darwin's Origin of Species is "survival of conscious, plamed behavior on the part of the fittest." By this Darwin meant that the the ptarmigan, but it is not. Just like the organism with adaptations that allow it to giraffe's long neck, the rattlesnake's rattles, acquire resources and reproduce more and the redwood tree's fire-resistant bark, effectively than another is the one that will the ptarmigan's dual-colored, variably survive. The wordfittest is perhaps insulated coat is the result of random misleading. This is another example of change over time that resulted in an common usage versus scientific usage of a organism adapted to live in the arctic. word. In common usage, because of the Other variations may have shown up in emphasis on physical prowess and athletic the ptarmigan's features along its conditioning, most students will think that evolutionary path, but those that the phrase means the most robust prevented survival in the arctic individuals will succeed. However, in the environment disappeared from the scientific sense of the phrase, it means the ones best adapted to respond to the shaped flowers. The flowers, however, pressures of the environment will survive. can range from pale pink to deep royal "Survival of .the fittest" thus means the purple. Colored flowers is a feature of organisms that fit best with their larkspur; the particular color of flower is a surroundings will thrive and reproduce. trait displayed by an individual plant, and FEATURES AND TRAITS may vary from plant to plant. Organisms have distinctive features that A classic scientific investigation looked at make them recognizable. Perch have the feature of wing color in the peppered scales, fins, eyes, and a mouth. Grasses moth of England. This little moth can have blade leaves, fibrous roots, tiny vary from almost white with dark dots on flowers, and lots of seeds. Snakes have the wings to completely black. In its scales, color patterns, eyes, and mouths. typical form it is Iight-colored. Light- Pine trees have massive stems, large roots, colored wings was the predominant trait needle leaves, and seeds in cones. Ducks before the Industrial Revolution. have feathers, beaks, legs, webbed feet, and When the Industrial Revolution filled the eyes. Cats have fur, eyes, teeth, color, and air with pollutants, the fragile light- tails. Features are structures of organisms. colored epiphytic lichens on tree trunks There is tremendous variation in features and branches died, leaving the dark from species to species but all individuals trunks exposed. The moths with the white of the same species have the same features. color trait were easy for predators to see There can, however, be variation in how on the tree trunks, and they were eaten. the features look within a species- Moths with the dark color trait were less variation from individual to individual. . often seen by predators, so they survived The appearance of a feature within a to reproduce. Moths with dark wings species is called a trait. A trait is the tended to have offspring with the dark- particular manner in which an organism wing trait. exhibits a feature, that is, how it looks. Humans have colored hair and colored Let's look at some examples. Black bears irises. Hair color and eye color are all have the same features: four legs, short features of humans. There is variation in tail, small ears, two eyes, long, coarse fur, hair color from jet black to nearly white and a brown nose, among others. The and variation in eye color from pale blue color of the fur can vary from jet black to and green to dark brown. Hair and eye honey yellow. In this case, fur color is the color are features of humans; the feature, and black fur is the trait for one particular hair color and eye color of an individual. individual are traits of that person. Larkspur is a plant that grows in moist The ideas of feature and trait are discussed meadows. The plants share common in greater detail in Investigation 9, when features that make them identifiable to we introduce the fundamental mechanism plant fanciers: small green leaves, tall that determines traits, the gene. central stems, and clusters of distinctively WHY DO I HAVE TO LEARN THIS? "So, people are different. I know that Many students think that adaptations, like already. Some people are tall and some warm fur, sharp talons, wings,- venom, have freckles. It doesn't really matter- webs, fins, and fragrance, are the clever we're all people-it's just that we are devices that organisms developed to help individuals. Individuals are supposed to them survive. They tend to attribute be different from one another. Otherwise conscious decision and deliberate action to the world would be too boring." the processes that produced the features and traits, for example, the giraffe grew its It's true, we are all people, just like neck to reach high branches; the frog grew goldfish are all goldfish, spotted owls are webs between its toes to swim better; the all spotted owls, and orcas are all orcas. mosquito developed a proboscis to suck Even so, there is variation in all blood; the monkey developed a prehensile populations, and the variation is doubtless tail to keep it from falling out of the trees. perceived and factored into the way members of a population interact. Ths is The idea that these and millions of other the level of awareness that middle adaptations emerged by chance or as schoolers will bring to the study of accidents is not intuitive to students. The variation, and it is a good place to start. idea that the adaptations we see today are the "happy accidents," the ones that An important notion for students to start worked to the organism's advantage and thinking about is that variation in traits helped it survive, is equally difficult. The may be present but undetected in a countless unhappy accidents that did not population. Traits that allow an organism help an organism survive are the features to respond to changes in the environment we can read about in the fossil record or can be the fulcrum on which the balance dream about, but they are not expressed by between life and death pivots. Such traits organisms on the planet today. may reveal themselves as important for survival when conditions change. An Students' understanding of ecology and animal that is just a little more heat natural selection hinges on the tolerant or a plant that sets seed just a bit fundamental concept of adaptation. earlier than others in its population could Carefully monitor their progress with this be the one that survives to reproduce if the difficult idea. Adaptations determine the environment presents a particular set of relationships organisms have with their challenges. In another instance, however, environment. An organism's- relationship it might just as easily be the individual with its environment is a matter of life and that is just a little more cold tolerant or death. And remember, an organism's sets seed a bit later that survives. environment is everything surrounding it, Variation within a species is one way to physical objects and conditions as well as - ~ ensure that some members of a population all the organisms of its own kind and every survive to continue the population line. other kind. PRISM UHH GK-12 Exploring Human Traits Genetic Variation Summary Genetics can be a confusing concept for many students to understand. In order for the class to begin to understand genetics, they will first study variation in human Concepts ;;l traits. Students will start learning about the study of heredity by surveying their Within a popul ation of own features. They will learn that they possess single gene traits with simple organisms, indi viduals dominance inheritance patterns such as earlobe attachment, tongue rolling, and will exhibit va riation or bent little finger. Students will work in groups, and after surveying their partners, differences a mong their the data of the class will be collected and patterns of inheritance will be discussed. features.
Genes are the basic units Objectives of heredity a nd they are Students will describe human traits. what make e ach • Students will distinguish which trait they possess for chosen features. individual’s • Students will organize data, calculate percentages, and create graphs. characteristic s, traits and • Students will identify patterns and discuss conclusions for those observed behaviors dif ferent. • patterns.
Standards addr essed Materials 7.1.3, 7.5.2, 7 .5.3 Rulers (1 for each group of 2)
Grid for Vocabulary Bingo, or have each student take out a piece of paper and Duration make their own grid (5 squares down x 5 squares across). 60 (+) minut es Vocabulary Review Sheet-Can be used as transparency or a handout.
Internet access if added background material is needed- Vocabulary
Genetics Teacher Prep Activity Variation Xerox “Genetic Variation” readings, grids for Vocabulary Bingo Genes • Vocabulary Review Worksheet and Exploring Human Traits Record DNA Sheets for students. Nucleic Acid s Xerox a single copy of the Human Traits that can be used for teacher. Chromosom e •
Alleles
Traits Background Dominant With the invention of better microscopes in the late nineteenth century, biologists Recessive were able to discover the basic facts of cell division and sexual reproduction. Homozygou s With these new discoveries, scientists began to focus genetics research to Heterozygou s understanding how hereditary traits are passed on from parents to their children.
Genetics is the branch of science that deals with inheritance of biological Source Mate rial characteristics. Within a population of organisms there will be variation among Adapted from FOSS the individuals in the population and this is the reason for population change and differences. Within a population of sexually reproducing organisms, every
individual within that population will be unique and vary in their traits, behaviors and environmental needs. Genes are the basic units of heredity and they are what make each individual’s characteristics, traits and behaviors different. Genes are found along the DNA strand. DNA (deoxyribonucleic acid) is made up of nucleic acids, which are large molecules that hold the story of life. DNA is the specific nucleic acid that deals with determining the genetic code of each individual. Typically, DNA molecules are quite long, approximately 5 cm long and in order to fit within the nucleus of the cell, they are coiled and tightly wound into a structure called a chromosome. branch of science that deals with inheritance of biological characteristics.
Organisms have different number of chromosomes, some organisms has as few as two, while some have up to a thousand. Humans have 23 different chromosomes and each of those has an identical partner chromosome. The paired chromosomes that are similar are considered to be homologues and each chromosome has the same genes. These two genes interact with each other to produce the characteristic they are assigned to and the two copies of the genes are called alleles. When the two alleles are considered together, they make up a single gene. When a gene is compos ed of two identical alleles it is considered homozygous. When the gene is composed of two different alle les, the gene is heterozygous.
Gregor Mende l, an European monk, became known as the “father of modern genetics” for his study of inheritance of traits in pe a plants. Through selective cross-breeding of different traits (tall, short, purple flower, white flower, smooth seed) of pea plants Mendel discovered the basic principles of heredity. Over many generations of breeding pea plants, Mendel discovered that certain traits show up in offspring without any blending of parent characteristic s. For example, when pollen from tall plants was used to pollinate the flowers of short plants, all the offspring we re tall. There was no mixing of tall and short plants. In the previous example, the trait of “tall” which exclusively appeared in the first generation (F ) and reappeared in the second generation (F ) was identified as the 1 2 dominant trait. The second generation also revealed the “short” trait that was absent in the F generation. This 1 trait that was absent in the F generation but present in the F generation was identified as the recessive trait. 1 2 Unfortunately, Mendel did not know about DNA, chromosomes, or genes and was unable to understand the biological and physical processes that allowed inheritance to occur and the importance of his work was not recognized until many years later.
Procedure
1). First have students read background information about Genetic Variation. This can either be assigned as homework, or this can be done as a lesson during class prior to this activity. If the reading is to be assigned as homework, be sure to take a period to go over the information since some of the vocabulary can be complex.
2). Play a round (or two) of Vocabulary Bingo and then review genetics vocabulary sheet as a class.
3). Divide students into groups of two and give each group a ruler (ruler will only be used if the traits that you assign to survey need to be measured). First ask the students if they think there are differences among humans and have them give examples of possible differences. Ask them if there were going to describe a person, for example, if they needed their parents to go pick up a friend that their parents had never met, how would they describe their friend to their parents. Hopefully they say things like “my friend has brown hair, they are tall, they have brown eyes, etc.”. Explain to them that they just described traits about a person. They will now survey their own traits.
4). On the list of traits provided, choose up to five traits and be sure to introduce the traits and go over them with the students. Each feature only has two traits, so each student should have one or the other trait. Let students know that their assignment is to discover which trait they have for each of the assigned features. For example, if the tongue trait is chosen, the student will either be able to curl their tongue or not.
5). Give the students about 10 minutes to observe each other and determine which traits they possess. Have the students record their traits on a piece of paper. They should write which feature they have and the trait, either the dominant or recessive trait. Dominant traits will be symbolized by 2 capital letters (TT) and recessive traits will be symbolized by 2 lower-cased letters (tt). This actually defines the genotype of the trait.
6). Poll the class by having the students come to the board and tally their results. On the board, have each trait written out and next to each trait, each student can make a tick or a check next to the trait.
For example:
Tongue rolling: TT __________“5 students”
tt ______“2 students”
Then determine the percentage of students in the class that have the certain trait.
The class can also be polled using a transparency, having the students raise their hands and report to the teacher which traits they have.
7). Talk about the results. Is there variation among the students? Which traits occurred the most? Are the traits linked? If you can roll your tongue, is your little finger always bent? Summarize the results, determining that there is variation among the students in the classroom. 8). Have the students create a bar graph of their results on the back of their Exploring Human Traits Record Sheet.
Teacher Resource Extensions: FOSS Genetic Vocabulary Review Worksheet (included) When introducing the material, students can visit the web site http://www.dnaftb.org/dnaftb/1/concept/index.html (DNA from the beginning) and choose chapters to explain some of these complex concepts. The animation tab for each chapter is a beneficial way to have students engaged in the material. Chapters 1-5 can be used for the topics of inheritance.
Resources file:///Users/universityofhawaiihilonsfprismgk-12/Desktop/GK-12%20/Human%20Traits.webarchive http://www.dnaftb.org/dnaftb/1/concept/index.html Foss-Populations and Ecosystems
Human Traits
1. Shape of face (probably Oval dominant, square recessive polygenic)
2. Cleft in chin No cleft dominant, cleft recessive
3. Hairline Widow peak dominant, straight hairline recessive
4. Eyebrow size Broad dominant, slender recessive
5. Eyebrow shape Separated dominant, joined recessive
6. Eyelash length Long dominant, short recessive
7. Dimples Dimples dominant, no dimples recessive
8. Earlobes Free lobe dominant, attached recessive
9. Eye shape Almond dominant, round recessive
10. Freckles Freckles dominant, no freckles recessive
11. Tongue rolling Roller dominant, nonroller recessive
12. Tongue folding Inability dominant, ability recessive
13. Finger mid-digital hair Hair dominant, no hair recessive
14. Hitch-hiker's thumb Straight thumb dominant, hitch-hiker thumb recessive
15. Bent little finger Bent dominant, straight recessive
16. Interlaced fingers Left thumb over right dominant, right over left recessive
17. Hair on back of hand Hair dominant, no hair recessive
Exploring Human Traits Record Sheet
Name:_ L_l ______
Use this tally sheet to keep track of the different traits that your classmates have. Under “Trait” write the different traits that your class has decided to survey, such as Dimples or Tongue Rolling. Under “Dominant” or “Recessive”, record the tally marks or check marks of your classmates. Then determine the percentage of students that are either dominant or recessive for the trait.
TRAIT DOMINANT RECESSIVE % (# ÷ Class total) Example: Dimples √√√√√√√√ √√√√ 8 ÷ 4 = 2% Dominant
______: ______(D) ______(r)
= ______%
______: ______(D) ______(r)
= ______%
______: ______(D) ______(r)
=______%
______: ______(D) ______(r)
=______%
______: ______(D) ______(r)
=______% Name -
Period - Date
'4 GENETICS VOCABULARY *****.***e.*e*.e *.*.*****....*....**..*. .. *...*.***.*****.
The offspring of organisms often grow up to look like one or b )th of their parents. This is because offspring inherit info mation from their parents that directs their development.
The inherited information 1 -1 rated in the of every cell in the organism. The information is coded in the 'luge molecule. The huge molecules are coiled into compact hot dog-shaped s. ictures called are always present in almost identical lirs. Locations on chromosomes that affect features of organisms are called . A gene is composed )f An organism's unique combination of genes is its . The traits produced
by an organism's genes is its . Alleles that ha more influence in determining traits are alleles. Alleles that have 1: , influence in determining traits are alleles.
1
FOSS Populations and Ecosyster Zourse 0 The Regents of the University c alifornia Investigation 9: Genetic Variation Can be duplicated for classroom c . vorkshop use. 55 Student Sheet Answer Key for Genetics Vocabulary Worksheet
1). Nucleus
2). DNA (nucleic acid)
3). Chromosomes
4). Chromosomes
5). Genes
6). Bases (sequence of bases or nucleotides)
7). Genotype
8). Phenotype
9). Dominant
10). Recessive
Answers for picture of cell
First Block: Chromosome
Second Block: Gene
Third Block: Nucleus
Fourth Block: Allele
PRISM UHH GK-12 Happy-Face Spider Propagation Genetic Variation Summary Students will act as captive breeders in order to simulate how genes are passed on from one generation to the next. They will also observe how small differences Concepts accumulate over time to produce descendants that look very different from their Genes are pa ssed on from ancestors. Students will use the Happy-face spiders (Theridion grallator a spider one generation to the next ), that is endemic to the Hawaiian Islands and exhibits genetic variation. Spiders on and this is the concept of heredity. Gene s code for the island of Maui follow basic Mendelian genetic patterns, so they will be useful organisms for this lesson. This simulation will help students determine how what an orga nism will look like and are carried genetic information is transferred during breeding, and what the resulting phenotype (how they look) will be. They will decide which traits are most by chromosom es. Chromosome s, which important to breed in order for better survival for the spiders. Students will also be introduced to Punnet squares, which will be used to predict the proportion of occur in near ly identical pairs in the nuc leus of offspring with each trait. every cell, ar e responsible for passing on hereditary Objectives Students will learn about a species that is endemic to Hawaii information. Depending • on which alle les an • Students will simulate how genes are passed from one generation to the next. organism has will determine how the • Students will act as captive breeders and choose which traits will help the survival of the spiders. organism wil l look and behave. • Students will use Punnet squares to predict the proportion or frequency of which genes will be passed on.
Standards addr essed Materials 7.5.2, 7.5.3, 7 .5.6 Pictures of Happy-face spiders that show variation in color. Pink and Blue Card Stock-each group of 2 students should have a total of 12 pink Duration 1-2 60 minut e class cards and 12 blue cards. (Size of playing cards). Need one set for use in explaining concept to students. periods Clear transparency to go over Punnet squares Paper for student Punnet squares. Vocabulary Happy-face Spider Hand-out of Happy-face Spider for students to color using their color choice.
Homologous Phenotype Background Happy-face spiders are found in the rainforests of the Big Island, Oahu, Maui and Genotype Punnet squar e Molokai. They are usually found on the underside of leaves. Happy-face spiders have a pattern on their body that resembles a smiley face. Every spider has a Probability Homozygou s unique pattern and the body color differs from island to island. Some of the spiders lack the pattern of the smiley face alltogether. These different morphs Heterozygou s Morphs (forms) are caused by the different gene versions carried by the spiders. The combination of alleles on the homologous chromosomes (similar, paired
Source Mate rial chromosomes) which determine a specific trait or characteristic is the organism’s genotype. The way the information is expressed and how the spider looks is PRISM considered its phenotype. Genotypes and phenotypes of an organism can be determined with the use of a Punnet square which estimate the probability
(likelihood) of genetic combinations being passed on to potential offspring. A Punnet square is created by crossing either homozygous (two identical alleles) alleles, heterozygous alleles (two different alleles) or a combination of both on a grid. Researchers believe that the variation of color and pattern in Happy-face Spiders is a possible type of camouflage against birds, their only significant natural predator.
In order for these spiders to escape predators they must be able to blend into their natural environment. If the student is to be the captive breeder they must decide what would be the best color for the spider to survive in the wild.
Teacher Pr ep for Activity
• Review background reading for Genetic Variation
• Xerox Happy-face Spider Drawing page.
• Cut out cards for the students: a group of two students will have one set of 12 blue cards and one set of 12 pi nk cards. Be sure to make a set to use as an example when explaining the activity to the students. Exc ept for the set to be used by the teacher, the other sets of cards should remain blank since the students will be writing in the color traits that they will be using. These cards could be laminated and used year afte r year, if dry erase markers that could be cleaned off were used.
• Have a clear transparency handy to go over the Punnet squares after they have finished the “card game”.
Procedure 1). Split stude nts into groups of two and pass out drawing sheet. One student will act as the MOTHER passing on traits to its offspring and they will receive 12 blank PINK cards. The other student will act as the FATHER passing on traits to its offspring and they will receive 12 blank BLUE cards. 2). Before the students start working on the cards, have them draw a Punnet square (more information about Punnet squa res can be found on pg. 257 in the FOSS readings at the back of the lessons) to determine what the probability of allele combinations will be (this can be done on the back of the drawing page). The students will have to choos e if the dominant parent will be either heterozygous (Ww) or homozygous (WW or ww). They should wor k together on creating the Punnet square. 3). Ask the students to determine which color they would like to represent. Remember: this color should be beneficial f or their survival in the wild. If a student chooses fluorescent pink, they will have to explain how this color woul d allow the spider to be camouflaged in the rainforest. The mother and the father should be 2 different colors. For example: Mom=White, Dad=Yellow. 4). Next, as k the students to choose which color is going to be dominant and which is going to be recessive and assign the c orrect genotype to the respective trait. Remember: the letter designated must be the same for each color but m ust be represented by either a capital letter or lower cased letter. For example, if mom is considered to be domi nant for White, then her genotype would be WW or Ww (students can choose, WW x ww will only have Ww of fspring which will all be the dominant color, white in this case. If more variation is wanted in offspring, ha ve the dominant parent be Ww, since Ww x ww will have 50% white and 50% yellow) and eventhough dad is yellow, his recessive genotype would be ww. 5). Ask the students to take a card and write one allele type per card. For example, for mom, each pink card should have a W written on half (6) the cards and the other half (6) will have a lower-cased w written on them, if you make m om heterozygous. If mom is homozygous then all her cards will have W on each one. For the blue cards, for da d, each card should have a lower-cased w written on it, since the gene is recessive he will only be passing the recessive gene on. 6). Now ha ve the student with the pink cards shuffle their cards and the student with the blue cards shuffle their cards as we ll. Then have the students lay all the pink cards out next to each other and below that row of cards, lay out all t he blue cards. Be sure the cards are lined up above and below each other to show how the different genes line up. 7). Once the cards are laid out, have the students look at the frequency of the combinations of traits. Ask the students to compare the probabilities of the allele combinations from their Punnet squares (on the back of their drawing pa ge) to the frequencies created from the cards they made.
Assessments Journal writing and coloring picture of spider to accompany writing or defense of color choice. Class presentation on spider color choice
Resources http://evolut ion.berkeley.edu/evolibrary/article/_0/happyface_02 Google ima ges-http://images.google.com/ Foss-Popul ations and Ecosystems
Name: ______
Color the body of the Happy-Face Spider the color that was chosen to breed the spider for survival in the wild. Use the extra space behind the spider to draw the habitat where this spider can be found.
UHH PRISM Drawing by: Bobby Hsu Bobby Hsu Look under a leaf and find a smiling surprise. But look out, because I like to catch my prey in a silken trap. WHO AM I?
Color the numbered spaces to find me.
1 = red 2 = black 3 =-.-.a fl In R. S-hL.+Cbo~03
Unscramble the letters to find out.
1. PYPAHEFAC DE PIRS Coloring and Activity Book .-...... - -b-..--.. 3565 Harding Avenue Honolulu, Hawai'i 96816 http://nature.berkeley.edu/~gillespi/re search.htm http://nature.berkeley.edu/~gillespi/research.htm http://nature.berkeley.edu/~gillespi/research.htm http://nature.berkeley.edu/~gillespi/research.ht m http://nature.berkeley.edu/~gillespi/research.htm In Genetic Variation students learn the basic genetic mechanisms that determine the traits express1 individu In.
SCIENC The individu als in evt ?rypopu: lation vai ry from c~ne another in their traits. Heredity is tlle passin g of info]nation f rom one generation to the next. . ,. . Chromosomes are structures that contaln .hereditary . information and transfer it to the next generation; they occur in nearly ic ientical F)airs in tE te nucleu .s of every cell. Gent es are thc ? basic urlits of he]redity ca~:ried by c:hromosa bmes. Ge nes code for features of or$ . . . -~ .~ ...... Alla... ,les are vanations ot genes that determe tralts in orgarusms; the two alleles on paired chrolmosome s constik~te a gene. Alle les can bc 2 dominamt or recessive. Dominant alleles exhibit the !ir effect if they arc 2 present on one chromosome; recrsslve alleles exhibit their effect only when they are on both chromosomes. An organism's particular combination of paired alleles is its genotype; the itraits pro duced by those alleles result in the organism's phenotype. A gene composed of two identical alleles (e.g. both dominant or both recessive) is homozygous; a gene composed of two different alleles (i.e. one dominant and one recessive) is heterozygous. CONDUCTING INVESTIGATIONS- Observe vari ation in 1luman tr(aits and 1arkey traits. Use a simula tion to dt2termine the trans fer of genetic information during breeding and the traits that result. Use Punnett squares to predict the proportion of offspring that will have certain traits. BUILDING EXPLANATIONS Explain how organisms Inherit features and traits from their parents. Describe how dominant and recessive alleles interact to produce traits in a population. - ;-, , - 1 SCIENTIFIC AND HISTORICAL BACKGROUND I In their ecoscenario studies, students were organisms in an ecosystem is one of the introduced to two dozen or so key monster questions in biology. Presumably organisms that interact in a particular life started on Earth as one kind (or ecosystem. That's quite a few organisms possibly several) and over the last 3.5 to keep track of for middle schoolers, but billion years diverged into hundreds of in fact, the handful of species presented for millions of different kinds, a small Fraction study represents only a tiny fraction of the of which are living on the planet at this actual number of species living and time. What process could have produced interacting in the most diverse and robust so many kinds of organisms? , ecosystems. . i Most biologists concur that the theory of Diversity raises questions. How can so natural selection provides the answer. The I many different populations live in the theory stands on several tenets. same ecosystem? And where did the First, there is variation in a population of different species come from in the first organisms. The variation can be the result place? of mutations and recombinations in the ; In Investigation 8 students were genetic code, but these concepts will not introduced to important concepts that get be pursued in this course. Variation in a at the first question. The simple answer is population may be the result of that all organisms living in an ecosystem immigration and emigration (gene flow) have adaptations that let them get the or the random change in the frequencies of resources they need to live and reproduce. alleles (genetic drift). We will accept as a Close analysis reveals that every species fact of life that there is variation in the has a unique suite of adaptations. This many features of individual organisms, ensures that when resources are limited, and they stem from natural processes. every organism will use at least slightly These variations are traits. different resources, in a slightly different Second, environments are dynamic, way, at a slightly different time, in a continually presenting new and different slightly different place. In this way challenges for the organisms living in organisms keep out of each other's way them. The environmental change could be and avoid excessive competition for the introduction of a new organism better valuable resources. In a sense an organism adapted to compete for resources, a is defined by its adaptations; similarly its change in the climate, a disaster of some role in the ecosystem is defined by its kind, or any number of subtler changes. adaptations. Organisms that are not An organism that was adapted before the adapted to live in a particular ecosystem change in the environment may not be are not found there. adapted to cope after the change. Why there are so many different kinds of Ecologists call this changed condition a selective pressure. The change in a very of time, from decades to scores of real way selects the organisms that will millennia, the two populations may have succeed and those that will fail. There is, diverged to such an extent that, even if of course, no conscious decision to select they were reunited, they would continue this organism and eliminate that one. to conduct their separate lives, unable to mate and reproduce. If the selective pressure is radical, a whole population may succumb. If the pressure That's an oversimplified picture of the is slight or incremental, however, the origin of species, but in practice the pressure may be felt by only some science of identifying the precise point in members of a population. That is to say, this process when a new species has some traits, such as thin fur, pale skin, or arrived is daunting, and even a precise short legs, might preclude an organism definition of what constitutes a species is from acquiring resources or reproducing, illusive. We will not enter these deep so those traits will be selected against in waters in this course. the population.- - Other members of the population might continue to survive and reproduce, perpetuating their traits. In MECHANISMS FOR POPULATION CHANGE this way the appearance and/ or behavior of a population as a whole can change, The key to population change is variation :. sometimes in a relatively short time. among the individuals in the population. -, In a population of sexually reproducing The third factor contributing to natural organisms, each individual is unique and selection and the evolution of new species therefore has ever-so-slightly different is isolation. As long as the members of a needs, behaviors, tolerances, and population interact and breed, they will responses to stimuli from the This discussion not normally generate a new species. The environment. When the environment applies to organisms population may change over time, but will that reproduce changes, the makeup of the population not become a new species. If one portion sexually. Organisms changes in response. of a population is separated from the that reproduce by simple division, other, either physically (isolated by What makes each individual unique? producing two Genes. The genes that direct the assembly geography) or behaviorally (exploiting genetic clone different food sources), creating two of molecules into organisms are different daughters, follow a populations, new species may evolve. for every individual. slightly different path to achieve When a portion of a population emigrates 1 population change. or is transported to an island or new continent, the selective pressures in the two environments-the originating environment and the new environment- may favor different traits. After a period The simple version of genetic transfer of The bases on two sugar / phosphate information goes like this. The story of life strands bond and form a double DNA is recorded in huge molecules called strand called a double helix. The result is nucleic acids. The specific nucleic acid a long ladder with the bonded bases that handles the genetic code is DNA forming the rungs. (deoxyribonucleic acid). The long filaments of DNA are made of millions of sugar- and phosphate units bonded together, with organic bases sticking out to the side. Picture a comb. The sugar /
backbone sports
like tines.
9 The bases sticking out are key to the structure of DNA. The four bases are adenine, thymine, guanine, and cytosine, usually represented by the symbols A, T, G, and C. The bases can bond with one another, but only in specific bonding pairs. A and T can bond with one another, and C and G can bond, but A cannot bond with C or G, and so on. Base pairing is specific, and there are no exceptions. A typical DNA molecule might be 5 cm Organisms have different numbers of long. To fit in the nucleus of a cell, the chromosomes-as few as two to well over huge molecule is coiled (wound into a a thousand. Most vertebrates fall into the helix) and recoiled into a compact 20- to 80-chromosome range, and humans structure called a chromosome. have 46. Toads have 22 chromosomes, and , chickens have 78. Plants and animals that reproduce sexually generally have an even Organismsthat have pairs of number of chromosomes because a set of - chromosomes are chromosomes is made of nearly identical called diploid. Some pairs. In humans, for instance, there are 23 organisms have distinctly different chromosomes, and each multiple copies of of those has an almost identical partner. similarchr~~oso*es The two similar chromoson~esare called and are polyploid. We will homologues. deal only with diploid Every cell in every plant and animal on organisms in this Earth has a complete set of chromosomes and in this course. that define the organism. 7'he chromosomes reside in the cell's nucleus. Every time a cell divides to produce two daughter cells, the complete set of chromosomes is duplicatecl. Each new cell is provided with a full complement of DNA-the complete set of blueprints and operating instructions for irssembling and managing one particular kind of organism.
The order in which the paired bases are aligned along the length of the DNA molecule is all important in decoding the message to make a new organism. Just like the 26-letter alphabet can be used to make untold numbers of words, depending on their sequence, the four-letter genetic code can make untold millions of "words," depending on the number and sequence of the bases. The plan for making a mosquito, tree frog, banana plant, gila monster, begonia, blue whale, or any other organism is encoded in the sequence of the same four bases distributed along the incredibly long double helix molecule. . ,..l ._/,: , ...... ,,: , .. , . ,8 ...... , ...... :;, :, .?.'..,:,!: .. i_. " ., DETERMINING TRAITS When alleles are identical, both forms of ;> ,);,., ,:;...';.~.:.::::,:~;< ;.$;'.; .,: , ;:Xb, '- ,. ., ,; :,< ;., ,",,., ....., - ,, . !. .. . , , .;...... :... Features, characteristics, traits, and the gene produce the protein that makes, : , , ,;I: ,,,\ l;~,..~~;>:,.:.:.;.'? .,<: ...... $ .,,,:,.; ~ , , ; . , , behaviors are determined by genes. Large attached Or a ,. .~.. ~..,. , ,,,;. :y . ,.:.,:;>'.:>!>\ widow's peak.
. ',. ~ . - ...... !.. ... ,ri2.. j .., ears on jackrabbits are determined by , ..: ' .:. .>'. 1, .>.:<;. ,:;. ;:c,. .:{%>, , , , ,. ?.. ' I .*:: >,,> ,,,:,. :. !'., . , , genes. The gray color of elephants is If the alleles are not the same, however, ...... , ., . .-. : ...... ~...: . . determined by genes. The spots on ,. -,. : .:&..- I ...,.',>".] ;I and the messages coming from the two .:, . : ...I ": ..... rainbow trout, the little friction area that ...... :tlj:j..;.... slightly differentalleles do not agree, what ...... , . :;...... II . .: /. ? .... lets crickets crick, and every other feature happens? ln the simplest case (the case . . : i .: .. .>. I .! :*. :,' ' . t ,. . of every organism is the product of a ...... !...... < .'...,...... ' ,: we introduce to students in this ...... , !:I, . . I. _ _ . ' . ,.. . genetic message. investigation), one of the alleles dominates .: ... &:.,,:. : ...... % ...... ? 1 ... the other and the effect of the dominant ...... :...... : , .. Genes are the units of heredity. Genes are ',, , . ~, ,. ...., gene is exhibited in the organism. Such an .-..... , .,! ::. : specific sequences of sugars, phosphates, , ,. .. > ,!,.',I ,.: ?:. ! allele is called a dominant allele, and the ...... - and bases along the DNA strand in the . ..i ....<...... : ....'. . _.. . . "overruled" allele is the recessive allele. . , . , . chromosome. A gene is a sequence of .. .. ,? :I , .-;.<.;:,.... ! , . + : bases that code for how to assemble a : ,, . ! .-.., :.':.. ,:...... , ., ...... , , ,: ,, certain protein. The proteins . . , . ,. . THE DISCOVERY OF HEREDITY . ... . - .... ,., .: . , ., ... .. ;.i... :... manufactured in response to these , , ...... :,,,i'. . :.c;*, . ..;., : .., ...... a ..... :: messages flow into the organisms' cells The pioneer work on heredity was ...... , - , < .. i.. . ..,. . , and make things. The things they make undertaken by the brilliant Gregor ...... ' . are fats, bone, muscle, nerves, and Mendel, son of a Moravian farmer. Young .... everything else that is required to make Mendel demonstrated an aptitude for . .'. . . .:. . :, ... .;,: ... . . organisms, complete with the characteristic academics, but was in no ~ositionto ... , . . . -.. , ; structures and behaviors that are both pursue a university career. In order to ...... ,. . typical of their kind and unique. continue his studies Mendel joined an Augustinian monastery. There he There is another important piece to undertook his detailed inquiry into the . . understanding genes. The homologous . role of heredity in conveying chromosomes (the two that are almost characteristics from one generation to the identical) each have the same genes. So it next. would seem that every organism has two genes for every characteristic. This is not Mendel worked extensively with pea entirely true because the two genes interact plants. He started his long series of to produce the characteristic. The two experiments by developing a number of copies of the gene are called alleles. The strains of pure breeding stock. He did this two alleles considered together constitute a by raising several generations of self- gene. fertilized plants. The result was separate populations of peas that produced clearly The homologous chromosomes are usually defined and predictable characteristics, identical with regard to gene location, but such as tall, short, purple flower, white are not identical in sequence of bases. flower, smooth seeds, and wrinkled seeds. Those differences in DNA structure can Whenever he planted seeds from his result in two forms of a gene or alleles. purple-flower stock, for example, all the experiments. He used pollen from tall constructed a functional model for genetic plants to pollinate the flowers on short heredity without knowing the biochemical . .. - : . I I. '. : ...... plants, and pollen from short plants to and physical processes that carry the ,. ,, .....:. ... ,'...... 8 ;:: . , pollinate the flowers on tall plants. What . , .. . process forward. , . . -:.<:.. . .:. . . . 1, :, ,, 1. , :;,: Mendel discovered was that all of the I,:>:, .v4, . ;.<. ..,, Tall and short are traits. The parental trait , . . : - . . offspring were tall. This was confusing to 1,,... ,,?? ~j, ,,'.. !::. , ...... :. . I that appeared exclusively in the F1 i ,,,~, . ;. . him. c,..+. .,....., j ,>,,....,. ." .>; generation and prevailed in the F2 , ,. ,.,: .,:.; ,,.: kc .(...... ,,. . . , I , ,...... -.-:?'. . . . Undaunted, Mendel collected the seed generation, Mendel identified as the iii...,, .,.. ~'.,_ ,: ' . . , . . . . from the tall pea plants, which he named dominant trait. The trait that disappeared !:;;.;',''I,. /. . ':..;.'.; . '
.' ,:,':' : the first filial generation (F1) and planted in the F1 generation but reappeared in the , , ..~.>. them (filial = son or daughter). Some of . . F2 generation, he dubbed the recessive ...... the offspring that grew from the F1 seeds trait. Whenever a seed acquired the 1', ...... , ,. ,,,, .:.- ;...... < . , ' (F2 generation) were tall, and some were dominant trait from both parents orfrom ::.i ;.. .I:. ~ ..- . . . short. Both characteristics were present in just one parent, the dominant trait was the offspring. The characteristic of height expressed in the plant that grew from that had not blended to produce all medium- seed. If the seed acquired the recessive height plants; the characteristics were traitfrom both parents, the recessive trait passed along intact, some exhibiting the was expressed by the plant that grew from tall trait and some the short trait. He that seed. concluded that even though all the F1 Some 150 years after Mendel puzzled out seeds came from plants that were tall, the probable mechanism for heredity, we when they grew into mature plants, some understand that dominant and recessive were tall and some were short. Both traits traits are transmitted by genes on were present in the offspring, the F2 chromosomes. When a gene is generation. represented by two dominant alleles, the Mendel paid close attention to the trait is that of the dominant allele (e.g. numbers of each growth form and purple flowers). Such a condition is called discovered that there were more tall homozygous (same allele) dominant. forms than short forms in the ratio of 3:1, When a gene is represented by two that is, 75% tall and 25% short. recessive alleles (homozygous recessive), the trait is that of the recessive allele (e.g. At this point Mendel made his white flowers). When a gene is revolutionary surmise. He reasoned that represented by one dominant allele and each offspring must get half its one recessive allele, the organism is information about height from each heterozygous (different alleles), and the parent. Further, the influence of the trait is that of the dominant allele (e.g. information from the two sources was not purple flowers). necessarily equal. Mendel knew nothing . ,...... i '. ! . ' Here is an important point. Where purple GENOTYPE AND PHENOTYPE ...... flowers are ehbited as a result of a Geneticists refer to the genetic makeup of heterozygous condition-the combination an organism as its genotype. F~~ ...... ,a ,!.,?. -. of a dominant and a recessive allelethe , .. instance, in the example of the two parent 5 ...... :.,. 3. ~ . .': .,,. .>:. . ,.>::,;. I ... . i. ":,; ...,,; , .., , . . : recessive allele for white flowers is still ,...... , pea plants, the gene for flower color can ' , , . , .:,...... ,... :. < ...... there. z ,._ ... be represented by the letter b (bloom). An , ...... +. : . \. ..-...... , . . ;. ,',;.c j . .I...... '.? ..;, . T. ...-.... I uppercase B represents a dominant allele , .'. .'. li , , ' .i for purple color, and a lowercase b ...., ', NEW COMBINATIONS OF ALLELES . , , . '.' .;, represents a recessive allele for white . . . , :.-.,. .,,5 .:;. 1 ...... ,, .;.. :4 ,~., ..:...... During the production of sperm and eggs, color. Our two heterozygous parents . , 'I'...... ,. ,.,: ...:...... a process called meiosis occurs, the would have the following genotype for . . , ., . ' ...... :. ::I homologous pairs of chromosomes < ,,. flower color: .. ,.,...... separate so that each egg or sperm cell has .. , ,. . .. - ...... ' . . only half of the usual number of ... :, ...... - ii i chromosomes. The two alleles that make a ...... ; I.,. . ,I I...... '. :. gene are, therefore, separated. (Meiosis, 9 ...... I ::;. . ,.. C' ...... the mechanism for passing just one allele ...... Hb Bb ,. ,...... \ from the male and one allele from the ...... -, . ' . .;. female to the offspring, is not explored in . a'.. ... , , this course, but it is one of the most The way the genes are expressed in fur, important factors in hereditary biology.) feather, flesh, and function is an See Page 53 in the During fertilization, one set of organism's phenotype. The simplest way Resources for chromosomes comes from the father to think of phenotype is how an organism diagrams of mitosis (sperm) and a homologous set comes from looks-its traits. Purple flowers, tall (cell division to form two daughter cells) the mother (egg). As the sperm and egg growth form, and wrinkled seeds are and meiosis (cell cells fuse, the two sets of chromosomes phenotypical traits. An organism's division to form create new homologous pairs of genotype determines its phenotype. chromosomes with corresponding alleles. During sexual reproduction, each parent The new sets of form genes that are contributes one allele to the genotype of unique to the offspring. the offspring. The heterozygous flowering If two purple-flowered parents are both peas .contribute either a B or a b. If either heterozygous for flower color, it is possible parent (or both) contributes the dominant that the recessive allele for white flowers B allele to the offspring, it will have purple will be passed to the offspring by both flowers. But there is a chance that both parents. Two purple-flowered parents can parents will contribute the recessive b have white-flowered offspring if both allele, in which case the offspring will parents had a recessive gene for white have white flowers. flowers, and each passed it to the offspring. This will happen, on average, in one out of every four offspring. PUNNETT SQUARES The completed Punnett square shows the *bout years ago ~~~~~~ldpunnett, a four possible combinations of alleles Cambridge professor of genetics, contributed by these two parents. These developed a simple and useful technique are possibilities linked with for predicting the characteristics of probability, not absolutes. offspring when the dominant and One homozygous dominant recessive traits of the parents are known. Two heterozygous It is known as the Punnett square. The One homozygous recessive square is a grid, with the alleles of one parent on the top and the alleles of the The heterozygous condition is always other parent on the left. The flower-color recorded with the dominant allele first, Punnett square looks like this. followed by the recessive allele.
...... -. :. ., 7,",' ... :L .: ...... ,...... ::, . < ,,. p! ':..: I I, ' ' . ' B b not bB . . Female ...... , ...... , ., ::.' -~,...... , I: , \:,,,.. ,: B b ., ;. ).. . ..>,' ..
BLENDED EFFECTS Each grid square represents the combination of two alleles. Transcribe It's not always that simple, however. Not those two alleles into the squares, like this. all alleles are wholly dominant or recessive. Some are partially dominant. In this case homozygous dominant alleles will produce one trait, homozygous Female recessive alleles will produce a second Bb trait, and heterozygous alleles will produce a third trait, often a blend of the two other traits. Students are introduced to this when they work with the feature of fur pattern on PRISM UHH GK-12 PRISM UHH GK-12 Natural Selection Hawaiian Origami Birds
Summary Concepts After students have a strong understanding of Adaptations and Genetic In 1859, Cha rles Darwin Variation, they will be introduced to Natural Selection. They will participate in and Aflred R ussel a natural selection simulation in which they will create and modify “paper Wallace propos ed the airplanes” over several generations to visualize how favorable heritable traits are theory of evol ution by passed on. These paper airplanes represent wild birds of a population. natural select ion. Their theory was la ter combined with Mendel ian Objectives inheritance to explain the • Students will simulate how genes are passed from one generation to the connection of genes (units next. of evolution) and natural • Students will understand how traits that are favorable for survival selection. Thi s theory has become more common over generations. become the pr inciple • Students will know that both genetic variation and environmental factors explanation f or species causes of evolution and species diversity. diversity. Materials Standards ad dressed Paper 7.5.4, 7.5.6 Ruler Tape Duration Straws 1 60 minute class periods Scissors Coin Source Mate rial Six-sided die w w w.indiana. edu/~ensiw eb/lessons/o rigami.html Background The Hawaiian Origami Bird (Aves hawaiiensis) lives on the rugged coastline of Vocabulary Hawaii Island. It feeds on Opae'ula (Halocaridina rubra) which are found in Natural Selec tion anchialine ponds around the island. Due to high development of the coastline on Phenotype the island, alchialine pools are decreasing and becoming less common. Only Genotype birds that can successfully fly the long distances in search of Opae'ula will live long enough to breed successfully. This simulation will allow students to breed several generations of the Hawaiian Origami Bird to see how phenotypes and genotypes are affected over time. Biological evolution, which is the gradual change to a population of species over many generations, is the process responsible for the diversity of species. Natural selection is the process by which favorable traits that are passed on over generations become more common in a population of reproducing organisms. Natural selection is also responsible for how unfavorable traits (not conducive for survival) become less common in the population. This process acts upon the phenotype or the morphological characteristics of an organism. Organisms that have favorable phenotypes that allow them to survive and reproduce in the wild are more likely to survive than organisms that have unfavorable phenotypes.
If the phenotype is based on genetics, then the genotype associated with that
favorable phenotype will increase in frequency in the next generation and
generations to follow. Natural selection also acts upon populations, not
individuals alone. The changes to the phenotype and genotype must affect the entire populations of organisms, not just select individuals of the population.
Teacher Prep for Activity • Prior to this lesson, the teacher can cut the paper into different sized strips. Be sure to make many strips of each size (they will vary from the original size of 3 cm x 20 cm). The width and circumference of the strips will increase or decrease by 1-2 cm after each generation. • Xerox Origami Data Sheets • The pr ocedure section can be Xeroxed and handed out or the diagrams can be written on the board.
Procedure 1). Split stude nts into groups of two. Each student will prepare an ancestral bird: Cut two strips of paper, each 3 cm x 20 cm. Loop one strip of paper with a 1 cm overlap and tape. Repeat for the other strip. Tape each loop 3 cm from the edge of the straw.
2). Breed off spring. Each Origami Bird lays a clutch of three eggs. Record the dimensions of each chick and hatch the birds using these instructions: a. The fir st egg has no mutations. It is a clone of the parent, this measurement will be the same as the ancestral bird. In the interest of time you may substitute the parent when testing this chick. b. The other two chicks have mutations. For each c hick, flip your coin and throw your die then record the results on the table. i.) The coi n flip determines where the mutation occurs: the head end or tail end of the animal. ii). The die throw determines how the mutations affect the wing:
After you have determined where the mutation occurs, cut new strips of paper and re-build another bird with the new measurements. You can use the strips from the original bird if able. iii). Lethal mutations: A mutation which results in a wing falling off of the straw, or in which the circumference of .the wing kujis skjmkjalkjlerkj tkjhakjn kjthe circumference of the straw, etc. is lethal. Fortunately, Aves hawaiie nsis birds are known to “double clutch” when an egg is lost. If you should get a lethal mutati on, disregard it and breed another chick.
3). Test the b irds: Release the b irds with a gentle, overhand pitch. It is important to release the birds as uniformly as possible. Test each bird twice.
4). The most successful bird is the one that can fly the farthest. Mark which c hick was the most successful on the tally sheet provided.
5). The most successful bird is the sole parent of the next generation. Use the measurements from this bird to be the parent of the next generation. The following generation will be continuing to breed, test, and record data for as many generations a s you can in the time allotted. Use the table to record the results of your coin flips and die throws, the dimensions of all chicks, and the most successful bird in each generation.
Extensions a nd assessment You can use t he following questions for discussion of the topic. These can either be turned in for credit or can be discussed during the next class period.
1. Did your e xperiment result in better flying birds?
2. Evolution i s the result of two processes: variation and selection. a. How did your experiment produce variation among the offspring? b. How did your experiment select offspring to breed the next generation?
3. Compare you r youngest bird with your neighbor’s youngest bird. a. Compare a nd contrast the wings of of other birds with your own. b. Explain why some aspects of the birds are similar. c Explain why some aspects of the birds are different.
4. Predict the appearance of your youngest bird’s descendants if: a. the selection conditions remain the same and the longest flying bird survives to produce the most .offspring. b. the selection conditions change the worst flying bird survives to produce the most offspring. c. the selection conditions change and the bird whose color blends with its environment survives to .pr oduce the most offspring.
5. Predict how the Aves hawaiiensis might adapt after the alchialine pools have disappeared from over development?
Name ______Date ______
Origami Bird Data Sheet
Flip coin, throw die, record results. Plan the baby chicks, record their dimensions, breed the chicks.
GENERATION 0:
No Mutation COIN COIN
3 x 20 3 x 20 ______x ______x _kk
Head k Tail Head Tail Head Tail
DIE DIE
3 cm 3 cm
Mark the winning bird. Only the most successful bird becomes a parent of the next generation. The “no mutation” chick in the next generation is identical to the winning bird in the immediately preceding generation. Continue to flip and throw, plan chicks, breed them, and test them for more generations.
PRISM UHH GK-12 Exploring the Ohia Common Garden Natural Selection Summary Concepts After students have a strong understanding of Adaptations and Genetic Variation, Changes to the they will be introduced to Natural Selection. They will visit the Ohia Common environment may affect Garden in Volcano, Hawaii to see how Ohia (Metrosideros polymorpha) from how an organi sm may different elevations have morphological differences. survive in the wild. Occasionally, organisms Objectives have the ability to activate • Students will simulate how genes are passed from one generation to the different phe notypes in next. response to its changing • Students will understand how traits that are favorable for survival become surroundings . This lesson more common over generations. uses an endemic Hawaiian • Students will know that both genetic variation and environmental factors tree species, Ohia, to show causes of evolution and species diversity. how this spec ies changes its phenotype in response Materials to different ha bitat Background information about Ohia to lecture students before visiting garden requirements . Permission to visit the garden Dr. Elizabeth Stacy-can give presentation at garden about Ohia Standards ad dressed 7.5.4, 7.5.6 Background Biological evolution, which is the gradual change to a population of species over Duration many generations, is the process responsible for the diversity of species. Natural 1 full day for field trip selection is the process by which favorable traits that are passed on over generations become more common in a population of reproducing organisms. Vocabulary Natural selection is also responsible for how unfavorable traits (not conducive for Natural sele ction survival) become less common in the population. This process acts upon the Phenotype phenotype or the morphological characteristics of an organism. Organisms that Genotype have favorable phenotypes that allow them to survive and reproduce in the wild Glabrous are more likely to survive than organisms that have unfavorable phenotypes.
Pubescent If the phenotype is based on genetics, then the genotype associated with that Phenotypic plasticity favorable phenotype will increase in frequency in the next generation and generations to follow. Natural selection also acts upon populations, not Source Mate rial individuals alone. The changes to the phenotype and genotype must affect the PRISM entire populations of organisms, not just select individuals of the population.
Ohia lehua (Metrosideros polymorpha) is a Hawaiian endemic plant found in almost all Hawaiian ecosystems. It is present on all Hawaiian islands, except Niihau and Kahoolawe. Ohia is an extremely variable plant that ranges in elevation from sea level to approximately 7000 feet. In order for Ohia to survive and reproduce at such drastic environments, species at different elevations have morphological differences. Ohia found at low elevations have larger, glabrous (smooth with no hair) leaves while ohia at high elevations have smaller, pubescent (with short fuzzy hair) leaves. One reason ohia at high elevations have smaller, fuzzy leaves is because they are closer to the sun and the fuzzy hair might protect the leaves from cold temperatures. Lower elevation Ohia are further from the sun and need a larger surface area to collect more sunlight and they are without fuzzy hair because they live at warmer temperatures. Ohia have a given phenotype, but also have the ability to change its phenotype in response to environmental changes. This phenomena is called phenotypic plasticity.
Teacher Prep for Activity Weeks prior to the field trip, Dr. Elizabeth Stacy at the University of Hawaii, Hilo must be contacted for access into the common garden. Dr. Stacy could possibly be available to meet with the students to discuss Ohia and natural selection also. Her contact information is: Elizabeth Stacy, Assistant Professor Department of Biology, Uni versity of Hawaii 200 West Kawili Street Hilo, Hawaii 96720, Email: [email protected]. Please give yourself many weeks to months in advance to plan this field trip.
Procedure After finalizi ng the plans to visit the Ohia common garden, give the students some background information on Ohia before vi siting the garden. At the garden, Dr. Stacy will talk about Ohia and its morphological differences. After the lecture, students will be split into groups and be asked to examine the different trees at the garden. They will be asked to collect a single leaf from a tr ee from high elevation, mid elevation and low elevation. After they have collected their leaves, they will be asked to explain why they think the leaves they collected belong to their respective habitats. After the field trip is compl eted, have the students write a reflection about their trip to the garden. They could also be asked to research anot her organism that displays phenotypic plasticity.
Assessment Journal writi ng Written repor t of another organism that displays phenotypic plasticity.
Extensions If the class is unable to visit the common garden or a project extension is needed, a possible class simulation of this exercise would be to grow tomato plants. Before growing the plants, ask the students if they think tomato plants (with t he same genotype) grown in sunlight would look different from tomato plants grown without sunlight. Ha ve them write down their predictions. Plant several plants in pots and place half the plants in direct sunlight and place the other half in the classroom, away from any light. Water and feed both sets of plants the same way. T he plants grown in direct sunlight should grow upright, reaching for the sun while the plants grown inside should grow low, creeping along searching for sunlight. This simulation shows that different environmental factors can a ffect how an organism survives.
NATURAL SI
GOAL Natural Selection introduces students to natural selection as the mechanism that produces change in the genetic makeup of a population.
OBJECTIVES SCIENCE CONTENT Environmental factors put selective pressure on populations. Natural seletion is the process by which the individuals best adapted to their environment tend to survive and pass their traits to subsequent generations. Members of a species are all the same kind of organisms and are different from all other kinds of organisms. CONDUCTING INVESTIGATIONS Use a game simulation to experience change in a population, resulting from selective pressure. Record and process information presented in a video about natural selection. Use a multimedia simulation to explore the effects of natural selection on a population. BUILDING EXPLANATIONS Describe how selective pressure can affect the genetic makeup of a population. Explain how the traits expressed by the members of a population can change naturally over time. SCIENTIFIC AND HISTORICAL BACKGROUND It may be said that natural selection is daily Darwin brought his book to print. The and hourly scrutinizing throughout the world, ideas disseminated quickly throughout the every variation, even the slightest; rejecting scientific community, and in their wake a that which is bad, preserving and adding up all new understanding of the progression of that is good; silently and insensibly working, life emerged. whenever and wherever opportunity offers, at the improver~entofeach organic being in NATURAL SELECTION relation to its organic and inorganic conditions of lqe. The idea is simple, really, and is -Charles Darwin constructed on some fundamental assumptions that have since been shown In 1831,22-year-old Charles Darwin to be sound. embarked on a 5-year voyage of discovery Nature Produces Variation. During the as resident naturalist aboard the survey process of reproduction, random changes ship Beagle. The impact of the incredibly occur in the genetic information directing diverse and complex biota he encountered the manufacture of a new unit-an in South America revolutionized his offspring. Extreme changes are usually perception of life on Earth. During the lethal, and no offspring result. Those voyage and the years following, Darwin genetic miscues are not perpetuated. formulated a theory explaining the Modest changes translate into often subtle uniqueness and origin of the organisms he and sometimes dramatic differences in discovered. It was many years, however, individuals. Individual offspring turn out before he finally published his famous to be unique; one perhaps a little larger, book, On the Origin of Species by Means of another more aggressive, and still others Natural Selection, in 1859. darker in color, slower to respond, having Darwin anguished over his manuscript. larger fins or wider teeth, on and on. The He was diligent in his science, wanting result is variation in populations. solid sources of evidence for his Life Is a Challenge. Many factors sveculative ideas. But even when the I converge to prevent organisms from theory was clearly described and enjoying a peaceful, relaxed, successful supported to hssatisfaction, he feared the existence. The physical environment can societal response to his propositions. The be harsh, and is often variable. Weather assumed affront to God, excused from the and catastrophe put pressure on role of creator of all nature, and the organisms that can stress, weaken, and kill reduced status of humanity, dismissed them. At the same time, nature produces from the pinnacle of creation, troubled many more organisms than can be Darwin. But when he found out that supported by the environment. Alfred Wallace had reached essentially the Organisms that are not adapted to same conclusions about natural selection withstand environmental pressures are and was preparing to publish his work, doomed to fail. Biotic factors put pressure on organisms. The measure of the success of a population Heterotrophc organisms eat other is its ability to withstand change in the organisms for energy and building blocks. environment and to prevail. Nature's Organisms that fail to acquire food die. hedge against complete disaster imposed On the other side of that equation, by disease, drought, or hoards of predators organisms that are taken for food also die. is variation. When a new pressure is Microbes sometimes invade organisms, imposed on a population, some causing disease. Life is always under individuals may succumb. But some will pressure. likely have adaptations that allow them to survive and reproduce more offspring Organisms in a Population Compete. than other individuals of that species. In Every species has a niche in which it lives this way the population continues, but and acquires the resources it needs for changes. survival. The problem is, all the other members of an organism's species are Darwin did not have the benefit of trying to make a living in that niche as understanding the fundamentals of well. This creates competition among genetics, although it was well accepted members of a population for access to that organisms passed the code for making limited resources. If resources are not reasonably accurate reproductions of limited, members of the population could themselves from generation to generation coexist without complications. Those through sexual processes. He was able to individuals that succeed in getting observe firsthand the variation within a resources and that successfully reproduce population, particularly when he observed pass their genes to the next generation. the finches on the Galfipagos Islands. The puzzle that Darwin pursued was how the The measure of the success of an countless kinds of organisms came into individual organism is whether or not it being. What forces created a new kind of survives and reproduces. The traits that organism? What was the origin of species? prepared a successful organism to complete its destiny are passed to the next If a population existed in a constant, generation. Traits that resulted in supportive environment, natural processes successful reproduction by their parents would produce variation in the are, in all likelihood, the traits that will population, and the individuals would all increase the offspring's chances of have reasonable chances of survival. The reproducing. Successful individuals pass success of a varied population would the tools of success to their offspring. perpetuate a varied population. As discussed earlier, however, the Pressure on the population might favor perversity of the physical environment some individuals over others because the and the pressures imposed by the biotic variations represent different adaptations, community don't allow for the idea of a and different adaptations affect the perfect organism, ideally equipped to potential for survival. So selective survive. Survival has to happen in a pressure on a population will favor some dynamic environment, so perfection is a individuals, which will reproduce, resources, and they thrived. As time influencing the distribution of traits in the passed, variation entered the population. individuals. The population changes in The most conspicuous variation was the response to selective pressure. (Notice, beak. Different subgroups within the individuals don't change in response to population were better adapted to exploit selective pressure; they only survive or die. different food sources. We can imagine Populations change depending on the that the members of the population that characteristics of the survivors.) sought similar food sources would associate, and other groups that shared Over time a population may change different traits would associate. Feeding sufficiently for science to judge it to be a behavior isolated subgroups within the different kind of organism than it was larger population. Breeding among the before the selective pressure was brought subgroup reinforced the trait that isolated to bear on the original population. How it in the first place, further separating the long does that take? And how different subgroup. does the "new" population have to be to be deemed a new species? Variation within the subgroup might have produced other traits that also tended to It isn't easy to answer these questions. A isolate the subgroup, perhaps coloration, new species may emerge in an extremely size, nesting habits, mating rituals, and so short time-a matter of days or weeks in forth. In time, isolation and change in the case of bacteria. Or it may take response to pressures from the millions and millions of years for a environment produced a new subspecies. successful species like the white shark or The exact time at which a splinter group is horseshoe crab to change enough to be awarded the status of species is a subject considered a new species. for scientific debate. There are few Darwin observed the finches on the absolutes for defining a species, so the GalApagos Islands. The 20 or so islands moment at which it happens is nebulous. are situated about 1000 km west of Ecuador. The current islands range in age Darwin concluded that speciation was a natural outcome of ongoing life processes: from about 700,000 to 4 million years, but (genetic) variation in a population, scientists suggest that there may have been selective pressure in the environment, and other islands or sea mounts in the area as isolation of a segment of the population. long as 10 million years ago. The point is Darwin's momentous discovery is often that the GalApagos Islands are young, and summarized as "survival of the fittest." any terrestrial life had to make its way This creates a mental image of a ferocious there across the open sea or through the battle for survival, with the biggest, air. strongest, most voracious individuals Some time ago a single finch species always surviving to continue their kind. arrived on the islands. Perhaps a small This is not an accurate picture. Fittest flock was blown off course in a storm. The doesn't necessarily mean the individual in birds apparently had no competitors for the best condition or the one with the biggest teeth and strongest bones. It through millions and millions of handoffs means the individual with the best without a fumble. adaptations to survive the pressure being The processes of variation, natural imposed by the environment. Fittest selection, and isolation have produced an simply means the best equipped to amazing array of organisms. There are survive and reproduce. millions of species alive on Earth today, Who or what determines fitness? The and for each one there were at least a selective pressure in the environment. The hundred species that are now extinct. The pressure might come from the weather. A process of evolution has produced a return of the ice ages will select for those continuous parade of new species, each individuals with adaptations for surviving adapted to the specific environments in cold and select against those without which it lived, and continues to do so adaptations for cold. A new predator that today. climbs trees will select for those tree- dwelling individuals that can flee or defend against the predator, and select ARTIFICIAL SELECTION against those that have no defensive A discussion of artificial selection might adaptations. A drought that reduces the shed light on the selection process. We acorn crop may select for the smaller humans have one adaptation (thanks to members of a population that can survive natural selection) that makes us a on less food and select against those that formidable organism to deal with-an require more food. The result of natural advanced brain. We can control our selection is that the genetic makeup, and environment to an unprecedented degree. therefore the suite of traits expressed by As a result we can manage food resources, the population, is constantly changing. create shelter, manipulate energy, control The change process in organisms is called other organisms, and re-create the world evolution. Organisms can be thought of we live in. as work in progress; they are constantly One human enterprise is manipulating the evolving from something into something traits of organisms through artificial else. selection. Think about the domestic dog. If you follow the evolutionary process Every breed From the skinny, shivering back in time, perhaps 3.5 billion years or Chihuahua to the robust, barrel-toting St. so, logically you eventually arrive at the Bernard, and all the retrievers, hounds, first living organisms on Earth. terriers, poodles, spaniels, bulldogs, collies, Remember, life is the Olympic flame that and Pomeranians in-between are the same burns in every organism. The flame is species. Where did all the diversity come handed from one organism to the next. If from? Variation, selection, and isolation. it goes out, it cannot be rekindled. Life Let's say you wanted to have a dog to has only one chance to carry the torch, and catch squid for you. Where would you get every organism guards it tenaciously as such a dog? Because there is no such dog, long as it can. So every organism alive you would have to breed one. Squid live today has received the precious fire in the water, so you need a dog that is dysfunction, or shvering, shows up as a enthusiastic about water and swims well. trait in the breed, it may be difficult or A retriever or a spaniel would be a good impossible to breed it out without losing breed to start with. So you get a bunch of the traits you selected for in the first place. retrievers and spaniels and show them a A reduced gene pool caused by inbreeding squid. Toss the squid in the water and see often introduces vulnerability and whch dogs jump in to grab it. Of the weakness into the breed, due to lack of original subset of water-loving dogs, only variation. a few will pass the "goes for squid" test. Artificial selection has been used for years Breed the squidophiles and raise the pups. to develop disease-resistant strains of Test them for squidophilia. Breed the most grains, higher-yielding corn, faster- promising of those. maturing soybeans, square tomatoes, Take the best squidders out in a boat and seedless watermelons, and hundreds of see how good they are at spotting a squid other agricultural plants. And, of course, in the water. Breed those with the best horses and livestock are selectively bred night vision. What's the best color (maybe for a variety of functions and products, black) and hair length (shorter the better). and the celebrated silk moth and the large Identify those sharp-eyed squidophiles and exotic goldfish called koi have been that have the darkest, shortest fur. The selectively bred for centuries to produce animals that have the traits that fit your the living products we see today. needs are the ones that you allow to Nahire does the same, but without reproduce to get more offspring with their purpose, allowing some individuals with traits. the right stuff to produce more offspring After many generations of selective than others in the population. But in breeding you produce a squid hound, nature, the selection is based on passing a equal to the task you want it to perform. test, not possessing arbitrarily desirable And if you find you are not completely traits. And the "right stuff" is having the satisfied with the dog's performance in the traits that better prepare the offspring to future (maybe the breed shakes after survive and reproduce, not measuring up getting back into the boat after snaring a to a set of predetermined criteria. squid), you can always continue to tinker You've heard the lament, "Just when I with the traits to make it "better" by learned the answers, they changed all the breeding members of the isolated questions." That's the way it goes out population that have the desirable trait, in there in the biosphere--every time an this case, stand and drip. organism "gets it right," the environment There is danger in this process. By changes the test, so the winner yesterday isolating a small population, you may not have the right stuff to win today. significantly reduce the diversity in the That's natural selection, and that's what gene pool. If a genetic weakness, such as a keeps life evolvkg on Earth. tendency to bite, kidney disease, joint WHY DO I HAVE TO LEARN THIS? This investigation presents some sensitive encourage students to engage them and issues. The ideas of natural selection and incorporate them into their growing evolution of life on Earth can bring catalog of shared human knowledge. scientific historical evidence and the very For a full discussion of the issues essence of scientific inquiry into conflict associated with the teaching of natural with deeply held beliefs concerning the selection, biological evolution, and the sacred origins of life. Both points of view origin of species, obtain this book or seek to answer the same questions, in a browse it on-line: Teaching about Evolution and where did I way: How did I get and the Nalure of Science. Details are in the come from? References chapter. Evolutionary biologists study the scientific evidence provided by the inventory of living organisms, and piece together the fragments of life's prehstory, to synthesize a credible story for the emergence and progressive redesign of life on Earth. According to the biologst, the 3.5-billion- year ongoing experiment has produced Homo sapiens and the several millions of other species living on Earth today. And the biologist suggests that, just as it has from the beginning, the description, distribution, and diversity of life on Earth today is a snapshot of a work in progress. The evolutionary processes will continue to reshape the image of life on Earth indefinitely. We are here now simply as a result of chance and natural selection, just like every other living thng. Ths course introduces students to the scientific explanation for the origin of species and, in the process, lays the groundwork for answering the questions of how I got here and where I came from. It is not the intent of this course to disparage the belief system of students. Rather, we present the science ideas and