CAS BI 107 Study Guide - Midterm Guide: Deep Homology, Bone Morphogenetic Protein 4, Melanocortin 1 Receptor
20 Oct 2016
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Both reversal and convergence lead to homoplasy (not due to common ancestry: convergence evolution of similar function and form not due to common descent. Desert plants have 2 characters in common spines and stems that photosynthesize for protection and to produce energy when leaves drop in wet season. Can be dna sequence, behavior, or morphological feature. Problem: in constructing phylogenies, we can"t always assume similar function and form due to common descent (may be homoplasy, but not homology which are species with a recent common ancestor: reversal reversion to a primitive state. By the principle of parsimony, reversal is an unlikely explanation of most evolution, but it does happen. Homoplasy usually results from convergent evolution or evolutionary reversal and usually reflects adaptive evolution in response to similar natural selection. Polyphyletic groups are used to group homoplastic traits (grouping by superficial traits that do not have evolutionary history. ie wings) Monophyletic group/clade group with ancestor species and all descendants.
