BIOL108 Lecture Notes - Lecture 4: Polyphyly, Paraphyly, Convergent Evolution

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL108
• Professor: Lien Luong

Document Summary

Clade contains a common ancestor and all of its descendants and no other unrelated taxa. A shared, derived character is called a synapomorphy. Relative to non-vertebrates, presence of vertebrae is a synapomorphy. Within the vertebrates, it is a symplesiomorphy. ( shared, ancestral state). Only synapomorphies are useful for reconstructing phylogenetic relationships. Homologous character states look the same and have the same evolutionary origin. Analogous character states appear the same but actually evolve independently through the process of convergent evolution. Molecular evidence can also be used to infer homologies. Analogous traits are structures in different species that are similar due to separate ancestries. (inherited from different ancestors, but often in similar environments). Convergent evolution is the independent evolution of similar traits in different lineages. Monophyletic contains a common ancestor and all of its descendants. The goal is to organize species into groups with common ancestry that reflect ancestor- descendant relationships.