BIOL359 Chapter Notes - Chapter 4: Convergent Evolution, Astragalus, Synapomorphy
26 Apr 2013
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Document Summary
The most closely related taxa have the most traits in common: nucleotide sequences, skeletal elements, embryonic development patterns etc. Synapomorphies identify monophyletic groups: synapomorphy: homologous trait shared among species, similar from a common ancestor shared, derived traits (type of trait useful in estimating phylogenies, monophyletic group/clade/lineage: a group that includes an ancestor & all its descendants. Synapomorphies identifies between monophyletic groups (@ different taxonomic level) Nested, each branching event adds one or more shared traits each branch with unique derived traits : cladistic methods: used to infer a phylogeny, determine which traits are more ancient and which are more derived. Outgroup analysis: the character state in the group of interest ingroup is compared to the state in very closely relatives that branched off earlier outgroup : cladogram: phylogenetic tree inferred by clustering synapomorphies as distinct branches. Synapomorphies are indicated on cladograms with bars across the branches. Limbs are derived from the limbs of common ancestors of tetrapods & lungfish.
