BIL 160 Lecture Notes - Lecture 5: Heterozygote Advantage, Heterosis, Genetic Drift
28 Apr 2016
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Document Summary
The more closely related that parents are the less heterozygous the offspring are likely to be. Why aren"t bad genes selected out: heterozygote advantage, maintained by mutation, gene flow, natural selection may not have removed it, may not reduce fitness. Not maladaptive unless it messes up reproduction. Mutation in a population: one allele will function better, phenotypes most common= wildtype (+), any allele other than wild=mutant. Ex: agouti fur, red eyes in drosophilia, black and white feather in penguin, fur in tiger: wild-mutant= forward mutation, or reversion mutation, little mutation + little population= big change. Balance model: balancing selection *read link, heterozygote advantage, frequency dependent. Against one allele, depending on how frequent it is. Mullerian (digusting/toxic) innate aversions can be passed on search image: predators often develop it for particular prey items ex: arctic, owls prey on lemmings. Neutral mutation model: kimura, went along for the ride, no use, but didn"t vanish. Genetic drift= major force in micro and macroevolution.
