BIOLOGY 1M03 Lecture Notes - Lecture 1: Dna Barcoding, Even-Toed Ungulate, Barcode
4 Dec 2017
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Document Summary
Case study: adaptive radiation of fanged frogs. Case study: adaptive radiation, then mass extinction of cichlids in lake victoria. Maximum parsimony assumes that the best explanation or pattern is the one that implies the least amount of change. Traditionally, cladograms based on morphological data place whales outside of the artiodactyls mammals that have hooves, an even number of toes, and an unusual pulley- shaped ankle bone (astragalus) The astragalus is proposed synapomorphy that previously identified artiodactlys as a monophyletic group. Recent data on gene sequences called short interspersed nuclear elements (sines) show that whales and hippos share several sine genes that are absent in other artiodactyl groups. These sines are shared derived traits (synapomorphies) and support the hypothesis that whales and hippos are indeed closely related. Whippo hypothesis is further supported by the contention that homoplasy in sines is very rare compared to morphology.
