BIOL 2400 Lecture Notes - Lecture 7: Uniformitarianism, Maximum Likelihood Estimation, Polytomy
25 Dec 2017
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Multiple genes to get accurate species tree. A base position site that has at least two different bases that are each present in at least two different species (taxa) Parsimony principle: the tree with the minimum number of hypothetical evolutionary changes: class example: pi are 2, 4 and 5 (at least 2 different base pairs and each in 2 different species) A large number of trees topologies are possible when you have more than 4 species. Each nucleotide is a potentially informative character but homoplasy common so only 4 possible character states. Genes differ in rate of evolution: slowly evolving genes useful for distantly related species, rapidly evolving genes useful for closely related species. Character state: parsimony or weighed parsimony (cladists, maximum likelihood. 10 taxa 2 027 025 unroofed trees. Is a principle that guides the selection of alternative hypotheses; the alternative requiring the fewest assumptions/steps is usually the best.
