Biology 1001A Lecture Notes - Lecture 20: Parallel Evolution, Synapomorphy, Autapomorphy
10 May 2016
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Document Summary
Phylogeny very often involves reconstructing evolutionary relationships, in order to do that, we need to know something about the type of traits that the most recent common ancestor had. Outgroup comparison relies on parsimony: simplest explanation is best. Whichever tree requires the fewest evolutionary changes (gains or losses of a trait, is probably correct. In the case that is present in the shark, which is an outgroup, and found in some of the ingroup, the trait is ancestral. The common ancestor of the shark and the members of the ingroup probably had that. Simplest and best explanation trait, while the evolution of the frog, duck, and person lost this trait in their lineages. More likely than derived independently because it is a simpler explanation; the common ancestor of the group had it and there was just one evolutionary event the trait was lost once.
