Biology 1001A Lecture Notes - Lecture 17: Monarch Butterfly, Symplesiomorphy, Autapomorphy
24 Aug 2013
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Document Summary
Phylogeny reconstructs this relationship common among all organisms. Living modern species or groups at tips; common ancestors at the nodes. The rotation or reflection of any node(s) has no effect on the evolutionary timeline of organisms displayed in the phylogeny. Evolutionary relationships among organisms reflect how recently (in time) groups of organisms shared a common ancestor. Phylogenies are constructed using patterns of similarity (the more similar things are the more recently they shared a common ancestor) Homology: when similarity usually reflects recently shared ancestry. E. g. bug wings, bird wings; whale sonar, bat sonar. Traits that are homologous support true phylogeny, but homoplasious traits will mislead one. Cladistic analysis: only shared, derived traits, or synapomorphies, are informative. Traits shared by two or more groups of species that are derived from recent evolutionary origin and inherited by a common ancestor. Symplesiomorphy: shared, but trait is also found in the common ancestor of the group.
