1. Phylogeny & Systematics The study of the diversity and relationships among organisms.

2. Phylogeny: Phylogeny: The evolutionary history of a species or group of related species The evolutionary history of a species or group of related species Systematics Systematics Classifying and determining the evolutionary relationship between organisms Classifying and determining the evolutionary relationship between organisms Data from fossils, comparative anatomy, molecules and genes Data from fossils, comparative anatomy, molecules and genes

3. Classification A way to organize our knowledge Taxonomy: Naming and classifying organisms. Taxonomy: Naming and classifying organisms. The Linnaean System: hierarchical The Linnaean System: hierarchical Seven categories: Domain Seven categories: Domain Kingdom Kingdom Phylum Phylum Class Class Order Order Family Family Genus Genus Species Species Each level is a taxon.

4. Figure 25.7 Hierarchical classification This does not necessarily reflect evolutionary history…..PhyloCode??

5. Carolus Linnaeus Carl Von Linne 18 th Century: Binomial Nomenclature 18 th Century: Binomial Nomenclature Two part naming system Consists of the genus and species Latin or Latinized Italics or underlined First word capitalized, second lower case. Apis mellifera : bee that brings honey

6. Nomenclature Process of naming species. Process of naming species. In the middle ages, scientists used Latin to describe species. In the middle ages, scientists used Latin to describe species. Apis puescens,thorace subgriseo,abdominase fusco, pedibus posticis glabris utrinque margine ciliatis Meaning: fuzzy bee with the grayish thorax, dusky-brown abdomen, hairless hind feet bordered with small hairs on both sides Honey Bee

7. Phylogenetic Tree Branching diagram that show evolutionary history. Branching diagram that show evolutionary history. The tree represents a hypothesis about evolutionary relationships. The tree represents a hypothesis about evolutionary relationships.

8. Branch points – divergence of 2 lineages from a common ancestor. Branch points – divergence of 2 lineages from a common ancestor. Sister Taxa – groups of organisms that share an immediate common ancestor. Sister Taxa – groups of organisms that share an immediate common ancestor. Rooted – branch point within the tree representing the last common ancestor of all taxa in the tree. Rooted – branch point within the tree representing the last common ancestor of all taxa in the tree. Polytomy – branch point from which more than two descendant groups emerge. Polytomy – branch point from which more than two descendant groups emerge. Rooted

9. Phyogenies are inferred from morphological and molecular data Homology vs. Analogy Homology vs. Analogy Not all similarity represents common ancestry. Not all similarity represents common ancestry. Homology: The greater number of homologies between organisms, the more closely related. Homology: The greater number of homologies between organisms, the more closely related.

10. Analogy: Similarities due to convergent evolution. (Similar environmental pressure) Analogy: Similarities due to convergent evolution. (Similar environmental pressure) Organisms may have evolved similar structures to survive in a particular environment. Organisms may have evolved similar structures to survive in a particular environment. Homoplasies Homoplasies

11. Molecular Systematics Comparisons of proteins and DNA Comparisons of proteins and DNA DNA with many similar base sequences = homologies. DNA with many similar base sequences = homologies.

12. Cladistics Common descent is the primary way to classify organisms Cladogram The last ancestor common to both the cat and dog families lived longer ago than the last common ancestor shared by leopards and domestic cats.. Clade: ancestral species and all descendents.

13. Figure 25.12 Cladistics and taxonomy

14. How are clades identified? Ancestral vs. Derived Shared ancestral (primitive) character – Originated in an ancestor of the taxon Backbone in mammals Shared derived character – An evolutionary novelty unique to a particular clade Hair in mammals

15. Monophyletic grouping Monophyletic grouping Single ancestor gave rise to all species in taxon. This is a valid clade. Single ancestor gave rise to all species in taxon. This is a valid clade. Polyphyletic Polyphyletic Grouping consists of various species that lack a common ancestor. Grouping consists of various species that lack a common ancestor. Paraphyletic Paraphyletic Does not include all members from ancestral form. Does not include all members from ancestral form.

16. A key step in cladistic analysis is outgroup comparison which is used to differentiate shared ancestral characters from shared derived ones Outgroup – Species from an evolutionary lineage that is known to have diverged before the lineage that includes the species we are studying. Ingroup – Species of study

17. Systematists can never be sure of finding the best tree in a large data set. They narrow the possibilities by applying the principles of maximum parsimony and maximum likelihood.

18. Maximum parsimony Maximum parsimony assumes that the tree that requires the fewest evolutionary events (appearances of shared derived characters) is most likely.