BIO-0014 Lecture Notes - Lecture 10: Genetic Distance, Cambrian Explosion, Gene Duplication
13 Feb 2017
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First phylogenetic tree iii: more modern phylogenetic tree, synapomorphies are traits that certain groups share from a common ancestor, like the tailbone in humans and primates v. Polytomy is a node that divides into three or more branches: suggests that not enough data were available to resolve which d. 2: read from the tips to the ancestor, cladistic approach, first method to infer phylogenetic trees. Introduced by willi hennig in the 60s: synapomorphies, traits found in two or more taxa that are present in recent common ancestor but missing in more distant ancestors. 2: several complications to resolve when inferring a tree i. ii. Traits may be similar due to independent evolution and not common ancestry. A reversal in a character change may occur, creating the appearance that no change occurred: for example loss of limbs in snakes, parsimony, used to identify the most likely tree i. ii.
