This week (June 8th – 12th) we are reviewing evolution. 1. Review the lecture on evolution 2. Watch the evidence of evolution video: https://www.khanacademy.org/science/high-school-biology/hs-evolution/hs- evidence-of-evolution/v/evidence-for-evolution 3. Watch the Types of Natural Selection video https://youtu.be/64JUJdZdDQo 4. Complete the Evolution Review Activity 5. Complete the Natural Selection Reading and Questions I am grading you based on the rubric below. If you get below a 70% I will allow you to redo the assignment. Evidence of Evolution & the Week 5 Remote Learning Mechanisms of Biodiversity Natural Selection The total variety of all the organisms in the biosphere= Biodiversity Where did all these different organisms come from? How are they related? Some organisms in a population are less likely to survive. Over time, natural selection results in changes in the inherited characteristics of a population. WHAT IS DARWIN’S THEORY? These changes increase a species’ fitness in its environment. Any inherited characteristic Ability of an individual to that increases an organism’s survive and reproduce in its chance of survival= specific environment= FITNESS ADAPTATION WHAT IS DARWIN’S THEORY? STRUGGLE FOR EXISTENCE: means that members of each species must compete for food, space, and other resources. SURVIVAL OF THE FITTEST: organisms which are better adapted to the environment will survive and reproduce, passing on their genes. DESCENT WITH MODIFICATION: suggests that each species has decended, with changes, from other species over time. • This idea suggests that all living species are related to each other, and that all species, living and extinct,share a common ancestor. Humans select for choose useful traits in Artificial Selection organisms (ex: dog breeds) Fossils are same age as rock they are found in, Fossil Record tell a story Closely related species living in different habitats have specialized traits (finches) Geographic Distribution Distantly related species living in similar habitats have similar traits (whale/shark) Evidence of Homologous Structures Limbs that look different but are made by the Evolution same bones Early stages of development in organisms Embryology have similar structures Similarities in DNA and proteins suggest DNA relatedness Seeing natural variation in populations (ex: See Natural Selection Occur peppered moth) Large scale evolutionary patterns and processes that occur over long periods of time = MACROEVOLUTION 1. Mass Extinction • At several times in Earth’s history large numbers of species became extinct at the same time, leads to bursts in evolution 2. Adaptive Radiation (Divergent Evolution) • When a single species or small group of species has evolved through natural selection into diverse forms that live in different ways (Galapagos finches) 3. Convergent Evolution • Unrelated organisms come to resemble each other from living in similar environments (Sharks & Whales) 4. Coevolution • Two species evolve in response to changes in each other over time (bee & flower) 5. Punctuated Equilibrium • Pattern of a long stable period interrupted by a brief period of more rapid change Sample Population Frequency of Alleles allele for allele for brown fur black fur 48% heterozygous black 16% homozygous black 36% homozygous The relative frequency is the number of brown times that an allele occurs in the gene pool compared to the occurrence of other alleles in the gene pool. RELATIVE FREQUENCY is often expressed as a EX: In this population percentage. Dominant B allele (black) = 40% Recessive b allele (brown) = 60% Natural selection on single-gene frequencies can lead to changes in allele frequencies and thus to EVOLUTON • EX: A population of normally brown lizards. Mutations produce new color choices. If red lizards are more visible to predators, they might be less likely to survive. Black lizards absorb more heat to warm up faster on cold days so they can move faster to get food and avoid predators. The allele for black may increase in frequency. In a small population this random change in allele frequency based on chance is called Genetic drift. Genetic drift can occur when a small group of individuals colonizes a new habitat. Individuals may carry alleles in different relative frequencies than in the larger population. The population they “found” will be different from the parent population. not through natural selection but by chance A situation in which allele frequencies change as a result of the migration of a small subgroup of the population = FOUNDER EFFECT Individuals at both ends of Individuals at one end of the Individuals at the middle of the curve have higher fitness curve have higher fitness than the curve have higher fitness than individuals in middle. individuals in middle or at other than individuals at either end. end. Three Types of Selection HARDY-WEINBERG PRINCIPLE 5 CONDITIONS REQUIRED TO MAINTAIN GENETIC EQUILIBRIUM FROM GENERATION TO GENERATION 1. Must be random mating 2. Population must be large 3. No movement in or out of population 4. No Mutations 5. No natural selection Speciation: The formation of new species Happens through reproductive isolation Behavioral Isolation Geographic Isolation Temporal Isolation Their behavior is different enough Geography prevents them from Timing of important life stages do to prevent them from mating mating not match up, preventing them • Ex: Some members of a species • Ex: a river, mountain, volcano, or from mating dance to get a mate, others sing. city divides a population, their • Ex: one group of trees sends and Overtime they will become a gene pools no longer mix, which receives pollen in May, and dancing species and a singing will lead to two separate species another group sends and receives species. over time. pollen in June. They will no longer mate with each other and will become separate species over time. Evolution Review Activity Please review the video https://www.khanacademy.org/science/high-school- biology/hs-evolution/hs-evidence-of-evolution/v/evidence-for-evolution before completing if you haven’t already 1. Some organisms have features that have different functions, but similar structures. One example is the forelimb of humans, dogs, birds, and whales. What term best describes the relationship between these forelimbs? a. They are homologous. b. They are embryological. c. They are analogous. d. They are vestigial. 2. How do fossils support evolution? a. The fossil record provides evidence that all organisms developed at the same time. b. Individual species disappear and reappear in the fossil record over time. c. Organisms in the fossil record are identical to living organisms. d. The fossil record provides evidence that organisms have changed over time. 3. What best describes the hind leg bones seen in the whale? a. Vestigial structures that had a function in an ancestor b. Analogous structures to the fins of living fish c. Fossil structures from an extinct ancestor Evolution Review Activity 4. Which of the following is the best evidence that two birds belong to the same species? a. The two birds eat the same food. b. The two birds have common behaviors. c. The two birds are the same size and color. d. The two birds mate and produce fertile offspring. 5. Snakes such as boa constrictors and pythons have tiny leg bones buried in their muscles. These leg bones are vestigial structures that have little or no known function in snakes. Which best explains the presence of these vestigial structures in snakes? a. Snakes evolved from organisms with legs. b. Snakes are developing legs for walking on land. c. Snakes born with an extra set of DNA develop legs as they mature. d. Snakes have only one copy of the allele for legs in their chromosomes. 6. In Florida, mice that live on the white sands of the barrier islands tend to be lighter in color than mice that live in the vegetation on the mainland. Which of the following statements describes how mice on the barrier islands most likely evolved their light coat color through natural selection? a. The light-colored mice were easier prey for birds than the dark-colored mice. b. The light-colored mice learned to shed more of their fur than the dark-colored mice. c. The light-colored mice had a greater reproductive advantage on the barrier islands than the dark-colored mice. d. The light-colored mice migrated from the mainland to the barrier islands more recently than the dark-colored mice 7. A scientist is trying to determine how closely related two species of plants are. Which of the following would be most useful for the scientist to compare? a. the root depths of the plants b. the leaf structures of the plants c. the genetic sequences of the plants d. the nutrient requirements of the plants Evolution Review Activity 8. The illustrations below show the embryos of a fish, a reptile, and a bird at the same stage of development. Which of the following can be concluded from the illustrations? a. All the embryos grow at the same rate. b. All the embryos will develop identical structures. c. All the organisms share a recent common ancestor. d. All the organisms will be the same relative size as adults. 9. Which of the following provides the weakest scientific evidence that two species have a common ancestor? a. comparing fossils b. comparing food sources c. comparing genetic information d. comparing homologous structures 10. The larvae of the common sulphur butterfly can be light green or bright yellow. Birds prey on the larvae, which are found on the green leaves of alfalfa plants. Based on the theory of natural selection, which of the following would scientists expect to observe in populations of common sulphur butterfly larvae? a. All the green larvae develop yellow stripes before metamorphosis. b. All the yellow larvae and none of the green larvae are eaten by birds.