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Unformatted text preview: 1 Evolutionary genetics Overview of terms (micro- and macroevolution) Population genetics and Hardy-Weinberg equilibrium Exceptions to H-W: mutation, drift, gene flow, assortative mating natural selection Micro- and macroevolution microevolution : a change in the gene pool (allele frequencies) of a population over successive generations macroevolution : the origin of new taxonomic groups (cladogenesis) [Campbell] plus modification of species ( anagenesis ) and extinction Micro- and macroevolution (2) speciation (the formation of new species) is the bridge between these two levels, and the reason that we have taxonomy (species, genus, family, ...) at all Today: population/evolutionary genetics 2 From genetics to evolution Darwin didnt know the mechanism of inheritance (didnt rule out Lamarckian inheritance) Mendels work rediscovered in 1900 Blending inheritance was a big problem! Variability would disappear X = ? What happens if "red" is dominant and the red parent is heterozygous (Aa)? ` ` ` Mendelian genetics preserve variability Population genetics: definitions Remember: phenotype, genotype, allele, locus, homozygous, heterozygous, dominant, recessive A population is a localized group of individuals capable of interbreeding and producing fertile offspring A gene pool consists of all the alleles for all loci in a population A locus (or allele) is fixed if all individuals in a population are homozygous for the same allele (0 or 100% frequency) Mendelian vs. quantitative traits Mendelian traits are discrete (yes/no, black/white): e.g. eye color (sort of), sex Quantitative or polygenic traits are continuous (skin color, height, weight, etc.) more complicated but the evolutionary ideas are similar 3...
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