1. The evolutionary history of a species The study/process of tracing the phylogeny of organisms to construct an evolutionary “Big Picture” relationships Chapter 26: Phylogeny and the Tree of Life PhylogenySystematics Tools of Study: Taxonomy and Cladograms

2. A. Tool #1 TaxonomyTaxonomic categories are incorporated into cladograms Phylogenetic Tree Taxonomy Lingo: 1. Taxon: The taxonomic group at any level Taxa(plural) Note proper form: 1.Genus Capitalized; species small case, 2.Both in italics or underlined (Phylocode) Taxonomic systems totally based on evolutionary relationships 2. Branch Point / Node: The divergence of 2 taxa from a common ancestor 3. Sister taxa: Taxa that share the most recent common ancestor 4. Rooted: 5. Polytomy: Branch Point (node) Sister Taxa Oldest branch to the left A branch of more than 2 immediate descendents showing unclear evolutionary relationships Mustela frenata polytomy Branch length Branch length can represent time or genetic change!

3. 6. Monophyletic taxon 7. Paraphyletic taxon 8. Polyphyletic taxon Contains all members of the same ancestry. This is the only valid taxon derived from a cladogram Invalid taxon because it consists of a group of some with similar ancestry (I&K), but not all (J plus A and all its descendents) of the ancestors or descendants Invalid taxon because it contains members that lack a common ancestor Cladograms & Proper Taxonomic Categories (Taxon) “one tribe” Mammalia Carnivora CanideaFelidea leopardcatWolfDog Perisodactyla Horse Zebra Mammalia Carnivora CanideaFelidea leapardcatWolf Perisodactyla HorseZebra Mammalia Carnivora CanideaFelidea leopardcatWolf Perisodactyla HorseZebra Dog

4. Vertebral Column Jaws Four walking legs Amniotic Egg Hai r Outgroup Shared primitive character Shared derived characters Clade Lamprey Tuna Salamander Turtle Leopard A phylogenic tree with a series of 2 way branches that present the divergence of related organisms through a common ancestor Tool #2 The Cladogram Ingroup Lancelet 7. Maximum Parsimony (Occam’s Razor) Parsimony Cladogram Lingo: A branch in the cladogram Traits (characters) that are of similar ancestry The trait that is found in all members of the cladogram The trait found in the continuing branch of the cladogram The comparative organism that does not have the shared primitive character The members of the cladogram that all have the shared primitive character b) More complex structures evolve from simpler structures 1. Clade 2. Homologous Characters 3. Shared primitive character 4. Shared derived character 6. Ingroup 5. Outgroup Protists - development of multicellularity Exception: Parasites The assumption that the simplest arrangement with the fewest required changes is the best explanation. Assumptions of parsimony include: It is more likely that a unique feature evolves only once and passed down as opposed to evolving twice in different groups a) ExceptionsExceptions: Birds - 4 chambered heart

5. #3 – Organism’s genome contains in evolutionary history A. Different genes evolve at different rates 1. DNA coding for ribosomal RNA (rRNA) changes slowly, best used when taxa diverged 100s mya 2. Mitochondrial DNA (mtDNA) evolves rapidly, best used when exploring recent events B. Gene duplicationGene duplicationUnequal crossing over during Prophase I that generates new genetic material, leading to molecular evolution ~Forms gene families: groups of related genes within an organism’s genome 1. Orthologous genes - homologous genes found in different species because of SPECIATIONOrthologous genes 2. Paralogous genes - formed from gene duplication, found in more than one copy in the SAME GENOME. Paralogous genes Ex. Human α-globin and β-globin genes (proteins on surface of RBCs)RBCs

6. Gene Duplication due to unequal crossing over Slide 5

7. Model for Evolution of Human Globin Genes Slide 18

8. Slide 5

11. Applying the Principle of Parsimony Slide 2

12. Traditional Cladogram “The Mammal- Bird Clade” New Cladogram “The Bird-Reptile Clade” Parsimony and the Analogy-verse-Homology Pitfall New evidence from other derived characters place birds with reptiles Four chambered heart evolved twice thus it is an analogous character not a homologous character

13. Example of Polytomy Normal (dichotomous) phylogeny Polytomy in phylogeny -At all branch points there are two immediate descendants -There’s a polytomy from which dragonflies, mayflies, & beetles arise, indicating that the relationships between these three lineages is not yet clear Slide 2

14. Branch Length Representing Genetic Change

15. Branch Length Indicating Time Slide 3