BIOL 312 Lecture Notes - Lecture 3: Phylogenetic Tree, Molecular Phylogenetics, Stalk-Eyed Fly
14 Nov 2017
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Document Summary
As the number of taxa (or sequences, etc) increases, the number of possible trees increases rapidly. Additive tree: show relative amount of change on one axis. Rooted vs unrooted trees: rooted tree informs of time and directionality the outgroup is highly important. Polytomy: more than two branches coming out of a node (fully resolved tree has no polytomies) Monophyletic: contains all the descendants of a common ancestor. All four on the right are a monophyletic group (as long as they all depended on same node). Paraphyletic: classifying things based on a common trait based on different levels of analysis. Identifying and scoring taxa for some phylogenetically informative characters . Characters and character-states, e. g. eye colour (brown, blue, green), leaves (present/absent), position. Characters: heritable, independent, homologous reflecting shared ancestry. Homology due to shared ancestry vs homoplasy not due to shared ancestry. Homoplasty: character similarity not due to common ancestry: convergent evolution, secondary loss.
