BIO SCI 97 Lecture Notes - Synapomorphy
30 Jan 2014
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Synapomorphy shared derived trait in 2 or more taxa that was present in their common ancestor and missing further back. Synapomorphies: cladogram = type of evolutionary tree built on cladistic principles. Parsimony method that implies as few evolutionary steps as possible. Coherence trees built using different synapomorphies should agree. Theory vs. hypothesis: theory (def): a proposed explanation for a very general class of phenomena. Hypothesis: a proposed explanation for a phenomenon or a set of observations. H1: giraffes with the longest necks have the most success in competition for food. They are most likely to survive and reproduce. Their offspring also have long necks: where did this hypothesis come from, both hypotheses consistent with gradual neck length increase observed in fossil record. If h1 is true, then h2 must be false, and vice versa. B -- h1 and h2 are not mutually exclusive they could both contribute to evolution of long necks.
