BIOL359 Chapter Notes -Synapomorphy, Base Pair, Dicotyledon
11 Jan 2015
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Phylogeny = evolutionary history of a group of species. Can be based on morphological, physiological and molecular data. Homologous trait shared amont certain species and is similar b/c it was modified in common ancestor. All synapomorphies are homologous traits, but not all homologus traits are synapomorphies. Synapomorphies are nested and identify evolutionary branch points. = allow for speciation to occur and each branch allows for one or more shared, derived traits to be formed. Out group analysis = character state in group of interest (ingroup) is compared to state in a very close relative that clearly branched off earlier (outgroup). Polarizes data, from it we infer direction of change. Convergent evolution occurs when natural slection favors similar structures as solutions to problems posed by similar environments. If convergent evolution has occurred, it does not qualify as synapomorphies. Reversal = dna base pair changes from ancestor then goes back to the ancestor later on in the phylogenetic tree.
