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Organizing Biodiversity with Evolutionary Trees

Organizing Biodiversity with Evolutionary Trees. Classification & Taxonomy. Aristotle - first classification system John Ray - developed classification system and a new concept of species Carolus Linnaeus - system of hierarchical classification and binomial nomenclature. What is Systematics?.

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Organizing Biodiversity with Evolutionary Trees

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  1. Organizing Biodiversity with Evolutionary Trees

  2. Classification & Taxonomy • Aristotle - first classification system • John Ray - developed classification system and a new concept of species • Carolus Linnaeus - system of hierarchical classification and binomial nomenclature

  3. What is Systematics? • Systematics is the branch of Biology that seeks to classify biodiversity using everything known about an organism in order to understand its evolutionary relationship to other organisms.

  4. Pre- Darwinian Post-Darwinian Organisms are grouped according to similar physical characteristics Organisms are grouped according to evolutionary relationships Early Classification vs. Modern Analysis

  5. Dichotomous Keys vs. Phylogentic Trees • How is the purpose of each of these diagrams different? • How is the structure different?

  6. Tree of Life • All organisms are related, but some are more closely related than others. • To represent the idea that all living things, despite their diversity, share a common ancestor, Darwin used the metaphor of a “tree of life”.

  7. Tree Thinking “The affinities of all the beings of the same class have sometimes been represented by a great tree…The green and budding twigs may represent existing species; and those produced during each former year may represent the long succession of extinct species… As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life.” • Charles Darwin, On the Origins of Species (1859)

  8. Darwin’s Tree This “tree” illustration was the only one included in Darwin’s Origin of Species. Image taken from http://www.mala.bc.ca/~johnstoi/darwin/origin_abridged.htm

  9. The Tree of Life Project • The Tree of Life Web Project (ToL) is a collaborative effort of biologists from around the world. The project seeks to create a “super tree” which organizes the diversity of organisms on Earth through their evolutionary history.

  10. Creating Evolutionary Trees • Comparative studies and fossils may be used to create initial phylogentic hypotheses • Molecular techniques may be used to test or refine initial hypotheses • Computer programs are readily available to analyze vast amounts of phylogenetic data

  11. Based on the following character table, draw a tree

  12. Cladograms and Phylogenetic Trees

  13. How to read a cladogram • Lines represent history through time. • Nodes represent ancestors that are extinct, but common to organisms

  14. Clade-istics • Clade--group of organisms that share their most recent common ancestor

  15. Evolutionary trees are hypotheses! • Different sources of evidence may lead to the development of competing trees • The principle of parsimony (choosing the least complex hypothesis) guides systematists in their reconstruction of trees

  16. The Principle of Parsimony

  17. What is Cladistics? • A method of analyzing evolutionary relationships between groups to construct a cladogram or “family tree” • The branching tips of a cladogram must represent a clade, an ancestral species and ALL its descendents.

  18. Clades No more Reptiles?? http://www.enchantedlearning.com/subjects/reptiles/printouts.shtml Using cladistics, the traditional reptile grouping does not include ALL descendents

  19. Methods Cladistic analysis involves comparing similarities (homologies) between organisms in order to determine primitive vs. derived characteristics. • Primitive - characteristics that all members of a group share • Derived - modified characteristics that only some members share • What is the connection between mutations and characteristic?

  20. Data Sources Morphology Fossils Behavior Physiology Geology Geography Molecular Evidence Ecology

  21. Reading • Read “Tree Thinking Challenge” • Which tree is more accurate? • What is the basis for trees? • What do nodes represent?

  22. Practice • Try the “odds” today and the “evens” for homework. • You will get an answer key on Wednesday! • They get harder as you go on!

  23. Today’s Activity Birdwing Butterflies: We will use a combination of geographic, physical, and genetic evidence to determine the evolutionary history of birdwing butterflies.

  24. More Activities Later in the Year • HIV Evolution: We will use a computer program to compare HIV virus and determine the evolutionary origin.

  25. Tools • Available Software for Phylogenetic Analysis • Molecular Data Bases on the Web PAUP http:/onyx.si.edu/PAUP Hennig86 http://www.vims.edu/`mes/hennig/software.html MacClade http://phylogeny.arizona.edu/macclade/macclade.htm Genbank http://www.ncbi.nim.nih.gov/Entrez Protein Information Resource (PIR) http://pir.georgetown.edu

  26. Resources • “A Science Primer: Classification and Phylogenetics”http://www.ncbi.nih.gov/About/primer/phylo.html • Baum, D.A.,et al. “ The Tree Thinking Challenge”Science 310:979-980. • Campbell, N.A. and Reece, J. B. Biology 6th edition. San Francisco: Benjamin Cummings, 2002. • Clos, L.M. “What is Cladistics?” [6/8/06] http://www.fossilnews.com/1996/cladistics.htm • Filson, R. “Island Biogeography and Evolution: Solving a Phylogenetic Puzzle with Molecular Genetics”http://www.accessexcellence.org/AE/AEPC/WWC/1995/simulation_island.html • Kramer, B. and Flammer, L. “Making Cladograms: Phylogeny, Evolution, and Comparative Anatomy” Evolution & Nature of Science Institutes (ENSI/SENSI), University of Indiana. [6/8/06] http://www.indiana.edu/~ensiweb/lessons/mclad.html • “Names & classifying living things”http://www.backyardnature.net/names.htm • Singer, F., et al “The Comparative Method, Hypothesis Testing & Phylogentic Analysis”The American Biology Teacher 63(7): 518-523. • Skelton, P. W., A. Smith, et al. (2002). Cladistics a practical primer on CD-ROM. Cambridge, The Open University; Cambridge University Press. • “The Tree of Life Web Project’http://www.tolweb.org/tree/ • “Tree-thinking Group”http://www.tree-thinking.org • “Understanding Evolution: An Evolution Web Site for Teachers”http://evolution.berkeley.edu/ • “What did Trex taste like? An introduction to how life is related”http://www.ucmp.berkeley.edu/education/explorations/tours/Trex/guide/index.html

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