BIOLOGY 1M03 Lecture Notes - Lecture 11: Even-Toed Ungulate, Convergent Evolution, Ichthyosaur
15 May 2017
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Document Summary
Maximum parsimony, homology and homoplasy, convergence and adaptive. The cladistics or maximum parsimony approach to inferring a phylogeny focuses on synapomorphies. A synapomorphy is a novel trait that a clade of organisms have and that others outside this clade lack. A novel trait that is in an ancestor that has t ha trait and all derived organisms contain that trait. Synapomorphy must be shared between all descendants and must be unique to the clade. The observed data can be explained through phylogenies and the one with the smallest mutations or change is selected as it is easier to explain and is more parsimonious. The more parsimonious approach is the more simplistic and easier to understand or justify. Monotremes do not have nipples, lactate through sweat glands. Homology: similarities are inherited from a common ancestor. Hox genes are conserved (genes that govern body form and what part of the embryo develops into what) Appear in the same order in the chromosome.
