BLG 144 Chapter Notes - Chapter 27: Phenetics, Synapomorphy, Convergent Evolution
12 Jan 2017
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Phylogeny: evolutionary history of a species or other related group. Systematics: naming + classifying of organisms based on their phylogeny. Phylogenetic trees illiustrates phylogenies: depicts ancestor-descendant relatioships. Branching pattern should match hierarchical system of classificaction: not always reflected. Organisms w/ shared history should be more similar: group organisms together based on level of trait-sharing. 2 approaches for using data to estimate trees: phenetics and cladistics. Phenetic approach: consider overall similarity of different organisms. Cladistic approach: only consider sharing of synamorphies: shared, derived trait found in. 2/more taxa, present in their most recent common ancestor but is missing in more distant ancestors. Ancestral trait: characteristic that existed in an ancestor. Derived trait: trait that"s a modified form of the ancestral trait, found in a descendant. Homology: similar traits due to common ancestry. Homoplasy: similarity among organisms of different species due to convergent evolution, not by common ancestry: ex. Icthyosaurs is an extinct reptile that looks a lot like dolphins.
