BIOL 2200 Lecture Notes - Lecture 12: Devonian, Distant Relatives, Tiktaalik
13 Feb 2017
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Document Summary
Molecular systematics: molecular tools help build trees when: Genes for essential function likely to evolve slowly: select genes most appropriate for tree being constructed. Slowly evolving genes for a tree with deep branches. Orthologous vs. paralogous genes: orthologous genes genes found in different species with a common ancestor. Ancestor has gene and speciation occurs, and gene inherited by both diverging groups. Genes diverge after speciation: paralogous genes gene duplication within a species. More than one copy, genes diverge over time. Mutations can lead to divergence and gene families: orthologous genes are examples of homology and can be a synapomorphy, paralogous genes can increase genetic variation within a species (2 of a gene, more mutations, more genetic drift) Telling evolutionary time: fossil dating can help estimate age, but not very accurate, molecular data offers the opportunity to more accurately calculate time since divergence.
