BIOL 1F90 Lecture 18: BIOL 1F90 lecture 18 winter 2016
25 Feb 2016
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Document Summary
Phylogeny: evolutionary history of a species or group of species. To propose a phylogeny, biologists use the tools of systematics. Trees are usually based on morphological or genetic data. A hypothesis of evolutionary relationships among various species. Anagenesis: single species evolves into a di erent species. Cladogenesis: a species diverges into two or more species. Group of species, taxon, consisting of the mose recent common ancestor and all of its descendants. Smaller and more recent clades are nested within larger clades that have older common ancestors. For larger taxa, common ancestor existed a log time ago (kingdom) For smaller taxa, common ancestor more recent (family or genus) Contains a common ancestor and some, but not all, of its descendants. Over time taxonomic groups will be reorganized so only monophyletic groups are recognized. Reptiles were a paraphyletic group because birds were excluded. Similarities among various species that occur because they are derived from a common.
