Science 9th grade LEARNING OBJECT LEARNING UNIT Which systems does biology use to organize living things in What is everything around us our planet? made of? S/K o Recognize the binomial nomenclature system. o Compare the arguments on biological classifications of the different taxonomic schools that contributed to the development of systematics. o Illustrate the relationships among some species through different phylogenetic groupings. o Associate the hierarchical classification of species with the process of evolution. o Explain the impact of the development of molecular techniques on the emergence of molecular systematics. o Produce a taxonomic key. o Explain how an herbarium works. Language English Socio cultural context of Colombia the LO Curricular axis Living environment Standard competencies I identify criteria to classify individuals in the same species. Background Knowledge Concepts on taxonomic categories. Work on the science of evolution and phylogenetic relationships expressed in cladograms. English Review topic Expressions of contrast and addition Vocabulary box Branch: an arm-like part of a tree. Dichotomous: involving two completely opposing ideas or things. Fin: a thin movable part on a fish’s body by which it balances, moves, changes direction, etc. Fur: the thick hair that covers the bodies of some animals. Genotype: the particular type and arrangement of genes that each organism has. Hierarchy: a system in which people or things are arranged according to their importance. Research: a detailed study of a subject, especially in order to discover (new) information or reach a (new) understanding. Phylogenetic: based on natural evolutionary relationships. NAME: _________________________________________________ GRADE: ________________________________________________ INTRODUCTION: The importance of organizing living things Planet Earth has special characteristics that allow the survival of numerous and diverse living things. Since time immemorial, humans (homo sapiens) have given names to the resources around them, including biological species, probably due to the need of distinguishing dangerous predators, recognizing edible species, selecting raw materials to make goods, etc. This nomenclature is local, since a living thing can receive different names depending on the population. For example, the opossum is known as zarigüeya, fara, chuca or rabipelao in Spanish. These names vary from one country or region to another. Knowing living things led scientists to the conclusion that they all have a series of characteristics common for some groups that distinguish them from the rest. So, they can be identified and grouped together in categories. Question: In the region where you live, are there animals or plants that receive more than one common name? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ Objectives: To explain the criteria used to classify individuals in the same species. To recognize the importance of taxonomy for the knowledge and conservation of the world’s biodiversity, particularly in Colombia. To analyze the hierarchical association of organisms with evolutionary processes for the classification of living things through binomial nomenclature. Activity 1: How are the living organisms around us named? We call the living organisms that surround us by their common names, like dog, cow, rose, cat, rice, among others. But they also have a taxonomic nomenclature suggested by Carl Linnaeus (1758). This nomenclature proposes two names, one that corresponds to the genus, and another one to the specific name. For example, the nomenclature for the dog is: Canis lupus Canis makes reference to the genus and starts with a capital letter. lupus is an epithet or specific name. Nomenclature for a Colombian dog breed Figure 1. Canis lupus familiaris. Colombian fino hound, descendant of European hunting dogs. Retrieved from: https://en.wikipedia.org/wiki/Colombian_fino_hound The discovery of America was one of the main events that motivated scientists of the 16th century to look for ways to organize and name specimens that were found during the explorations of the new continent. Nearly two centuries passed before Carl Linnaeus (1758) established the basis for the modern classification system and the binomial nomenclature. Linnaeus grouped many organisms according to their morphology, that is, their physical characteristics. Binomial nomenclature consists in giving two names for a species, like in the example of the dog. Taxonomic schools Within the history of systematics, we find three schools: Evolutionary, Phenetic and Cladistic. 1. Evolutionary School: It states that when a classification is made, the common ancestor and the evolutionary changes of the species should be taken into account, as well as the interaction with the environment which may have caused the species to separate from its ancestor. For example, since birds have adapted to air, they must be classified in a category superior to that of crocodiles, but both of these species have a common ancestor which would make them part of the same group: reptiles. This can be observed in figure 2. Relationship between birds and reptiles Figure 2. Relationship between current birds and reptiles, as suggested by the Evolutionary School. Retrieved from: https://es.wikipedia.org/wiki/Sistem%C3%A1tica_evolutiva 2. Phenetic School: suggests that classifications should be made taking into account the greatest quantity of measurable, countable and observable characteristics in organisms, analyzing them through numerical techniques. In figure 3, you can observe the similarity among six species, with a similarity coefficient from 0,0 to 1,0. Instead of genealogical evolutionary relationships, this school takes morphology into account. Similarity coefficient of six species Figure 3. Phenogram with similarity coefficient, suggested by the Phenetic School. Comparison of the coefficient of similarity among six species. Retrieved from: http://perso.wanadoo.es/jjdeharo/sistematica/curso/s3.htm#_Toc471623355 3. Cladistic School: the classification is based on the evolutionary (phylogenetic) relationships of organisms. These are grouped together depending on whether or not they have one or several unique characteristics in common that come from the last common ancestor of the group and that are not present in older ancestors. They are expressed in a cladogram. For example, figure 4 shows a cladogram of evolution of terrestrial animals, presenting a possible evolution from the lamprey (jawless fish) to the gorilla. Cladogram of species evolution Figure 4. Cladogram showing evolutionary relationships of terrestrial animals, from an agnathan (fish) to a mammal (gorilla), with the evolution of characteristics like the presence of jaws, lungs, dry skin, fur, and the absence of a tail. Retrieved from: https://commons.wikimedia.org/wiki/File:Cladograma.png Remember that… The cladogram considers shared characteristics derived from the evolutionary relationships of organisms. Learning activity: The goal of this activity is to recognize morphological characteristics that have appeared evolutionarily in some species and place them in a cladogram. Instructions: 1. Observe the cladogram in figure 5 and the evolutionary characteristics that it includes on the branches. 2. Join two classmates. Discuss and write down the characteristics that the organisms share with their ancestors. 3. In a paragraph of no more than 10 lines, explain the characteristics that they share with other groups. Relationship among a bacterium, a fungus, a butterfly, a fish, a lizard, and a mouse 1. Bacterium: _____________________ 2. Fungus: ______________________ 3. Butterfly: ____________________ 4. Fish: _________________________ 5. Lizard: _____________________ 6. Mouse: _______________________ Figure 5. Cladogram. The red lines indicate shared characteristics. Retrieved from: http://www.taringa.net/posts/info/1316625/Cladogramas-Ilustrando-el-parentesco-evolutivo.html Activity 2: Taxonomy Taxonomy expresses “order”. It is based on the classification that is applied in biology for the systematic and hierarchical ordering of the groups of living things like, for example, animals, plants and bacteria. The relationships among the organisms are analyzed, with the goal of creating the phylogenetic tree of a given organism, and the evolutionary branches are found. Taxonomy is in charge of studying relationships. In the world there’s a diversity of species. 54.871 species have been registered in Colombia, so it is essential to implement a classification system that permits us: To establish evolutionary paths that have led to current species. To group organisms in categories based on comparative, morphological, cellular, evolutionary, molecular, and ecological characteristics. To give unique names to organisms. Currently, molecular genetic techniques like PCR (polymerase chain reaction) and electrophoresis (separation of proteins based on molecular weight) are being used. During the past decades, these techniques have become more important for the studies of evolutionary relationships, since they allow us to identify the relationships between different types of organisms through the genotype expressed in the DNA’s nucleotide sequence, the RNA sequence and in cellular proteins. It’s important to highlight that the evolutionary relationship is closer when there are