BIOLOGY 202L Lecture Notes - Lecture 22: Reverse Transcriptase, Opsin, Nucleotide Diversity
21 Jan 2016
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Snp/marker alleles near adaptive allele (0 to low recombination) hitchhike : reduction in pi, no/low nucleotide diversity indicates recent evolution. Immediate loss of diversity, but after a while, diversity returns through other mutations/etc: scan and look for areas with little to no snps consistent with theory of little to no nucleotide diversity. Window surrounding favored mutation where now no nucleotide diversity exists because of hitchhiking alleles around it. Near: effects of no recombination = entire gene region preserved/duplicated, large decrease in pi over many snps. Pi not reduced in region further from the mutation (variation maintained) Pi reduced greatly in region surrounding mutation (linked) Some organisms have genes that others do not . Horizontal gene transfer: from one species to another via viruses (rare in eukaryotes, common in bacteria) gene duplication (common in all organisms) Whole genome duplication: polyploidization common in plants, for example. Possible fates of duplicate genes when fixed in species via drift or selection.
