BIOL108 Lecture Notes - Lecture 6: Species Ii, Ingroups And Outgroups, Polyphyly

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL108
• Professor: Heather Proctor

Document Summary

Phylogenetic trees show evolutionary relationships, not phenotypic similarity. They often do not reflect dates/ times of evolution. Also, sister taxon do not evolve from one another: phylogenies are derived from morphological and molecular data. Phenotypic and genetic similarities due to shared ancestry are called homologies: distinguishing between homology (shared ancestry) and analogy (shared structure) is very important in determining phylogenies. For example, all of the ingroup may contain vertebrate column, signifying the divergence between the outgroup and ingroup. If rate of change occurs faster in one branch, we would expect greater evolutionary change in that branch: to find the evolutionary distance /divergence between two organisms, simply add the percentages along the branches that separate them. Each tree would have one of the species branching off and then the divergence of the other two. Tree i would have species iii branch off (with two evolutionary changes; position 3 becomes a and 4/c).