ANTHROP 2D03 Lecture Notes - Lecture 6: Computational Phylogenetics, Binary Tree, Speciation
26 Oct 2016
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Speciation - evolution of a new species. We have seen how variation can arise in a population, and cause it to change over time. A phylogeny, or species/ evolutionary free, represents the evolutionary relationships among a set of organisms or groups of organisms, called taxa (singular: taxon) that are believed to have a common ancestor. The tips of the tree represent groups of descendent taxa (often species) The internal nodes of the tree represent the common ancestors of those descendents. The tips are the present and the internal nodes are the past. The edge lengths in some trees correspond to time estimates - evolutionary time. Two descendents that split from the same node are called sister groups. For any species event on a phylogeny, the choice of which lineage goes to the right and which one goes to the left is arbitrary. Many phylogenies also include an outgroup - a taxon outside the group of interest.
