Biology 1002B Lecture Notes - Lecture 18: Cladogenesis, Convergent Evolution, Reproductive Isolation

• School: Western University
• Department: Biology
• Course: Biology 1002B
• Professor: Tom Haffie

Document Summary

Only synapomorphies are informative (not all similarities are homologies, not all homologies are synapomorphies). Homoplasy is misleading in that it can create similarity between distantly related groups (convergence) and can erase similarity between closely related groups (divergence). Most parsimonious tree (fewest evolutionary steps) is usually the best. Many currently-recognized groups are not monophyletic and thus good groupings. Monophyletic: the inclusion of all descendants of the group"s most recent common ancestor. E. g. crocodilians share a closer common ancestor with birds than with lizards. Prokaryotes: eukaryotes are more related (share a closer common ancestor) with archaea than with prokaryotes. Fish: fish are more related to reptilians than with sharks. Birds: birds are more related to crocodilians than with mammals, despite them being endotherms. The fossil record, the mode and tempo of evolution, and evolutionary trends (such as changes in body size) are all common patterns in macroevolution.