Earth Sciences 2266F/G Lecture 2: EARTH-L2
23 Jan 2020
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Classification and phylogeny: organisms diverging from common ancestor, where it touches if point of divergence in phylogenic trees most interested in relatedness of organism. Disadvantages of using traditional taxonomy: organisms can be related but not look alike there are 2 major groups that have diverge out. Mammals diverge early on but birds are more related to dino then lizards/snakes: birds can be considered as dino, cause we are looking at relatedness there are many categories. Enter cladistics: hypothesizing relationships among organisms, clades are unified groups (group of organisms that contain one common ancestor and descendants, pic: within the large clade there is a smaller one. Internal nodes: common ancestors of descendants in each clade (point of speciation) Root: hypothetical common ancestor of all taxa in clade. Synapomorphy: an apomorphic character shared by 2/more groups which originated in last common ancestor.
