Summer 2008 Workshop in Biology and Multimedia for High School Teachers

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? 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.

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

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”.

Tree Thinking Charles Darwin, On the Origins of Species (1859) “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.”

Darwin’s Tree This “tree” illustration was the only one included in Darwin’s O rigin of Species. Image taken from

Ernst Haeckel’s tree diagrams continued to develop the idea that all living organisms are related. He included microorganisms and was the first to use the term “Protista”. Haeckel’ s Tree

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

Data Sources Fossils Morphology Geography Molecular Evidence Geology Physiology Behavior Ecology

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

Tools Available Software for Phylogenetic Analysis Molecular Data Bases on the Web Biology Workbench NCBI Blast - ClustalW - Genbank - Ribosomal Database Project II -

Using Molecular Data In 1977, Carl Woese used molecular data from ribosomal RNA to classify microbes. Previously, microbes classification was limited due to their lack of identifiable characteristics. Woese’s work led to the current three “domain” system of classification: Archaea, Bacteria, Eukarya “ Old ” World View of Biodiversity PlantaeAnimalia Fungi Monera Protista Drawn by Christine Rodriguez

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. Figure courtesy of David Hillis

Resources “A Science Primer: Classification and Phylogenetics” Baum, D.A.,et al. “ The Tree Thinking Challenge” Science 310: Campbell, N.A. and Reece, J. B. Biology 6th edition. San Francisco: Benjamin Cummings, Clos, L.M. “What is Cladistics?” [6/8/06] Filson, R. “Island Biogeography and Evolution: Solving a Phylogenetic Puzzle with Molecular Genetics” 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] “Names & classifying living things” Singer, F., et al “The Comparative Method, Hypothesis Testing & Phylogentic Analysis” The American Biology Teacher 63(7): 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’ “Tree-thinking Group” “Understanding Evolution: An Evolution Web Site for Teachers” “What did Trex taste like? An introduction to how life is related” Dawson, Scott “Creatures from the Black Lagoon: Lessons in the Diversity and Evolution of Eukaryotes”