BIOL359 Study Guide - Midterm Guide: Tephritidae, Bird Louse, Molecular Phylogenetics
8 Oct 2013
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Document Summary
Phylogenies can be based on morphological data, physiological data, molecular data or all three. Today, phylogenies are usually constructed using dna sequence data. Generally several genes are used to construct a phylogeny. The genes used may be slowly-evolving (suitable for study of an old group of organisms) or rapidly evolving (suitable for study of a recent group of organisms). To construct phylogenies, phylogenetic characters are used attributes of an organism that can provide insights into its history (and shared ancestry). For example, molecular phylogenies use nucleotide positions as characters, with the character states a, c, G, or t. four cladistic character state definitions exist: plesiomorphy, apomorphy, synapomorphy and autapomorphy. Plesiomorphy refers to the ancestral character state the state possessed by the individual at the root of the phylogenetic tree. Apomorphy refers to a character state that is different from the ancestral state, or derived state. All apomorphies must be either synapomorphies or autapomorphies.
