Biology 1001A Lecture Notes - Lecture 19: Symplesiomorphy, Synapomorphy, Autapomorphy

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greymink18

14 Dec 2015

School

Western University

Department

Biology

Course

Biology 1001A

Professor

Beth Mac Dougall- Shackleton

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Document Summary

Meaning of synapomorphy, symplesiomorphy, autapomorphy; and know which of these is considered informative in cladistic analysis. Evolution of that trait happened in some point in evolutionary history. Use to identify which groups are closely related to e. o. Ancestral (trait was already present) before the groups diverged) Not useful to us to constructing monophyleny. Trait already present in ancestor of group before divergence. Ex. scaly skin of cameelians and turtles, so all the ancestors would have had scaly skin. Only one group has this trait (ex. only lizards have) How the principle of parsimony informs outgroup analysis and helps identify the most likely phylogeny. Whichever tree requires the fewest evolutionary changes (gains or losses of a trait) is probably correct. Can use parsimony if we have multiple phylogenetic trees and don"t know how to evaluate them. Traits that are, and are not, synapomorphies (given a suitable outgroup and a distribution of traits)

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