BS 182H Chapter Notes - Chapter 19: Allele Frequency, Assortative Mating, Genetic Drift
17 Mar 2016
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Inherit gradually better traits: lamarck thought that acquired traits could be passed on, there"s still a lot of variation; not every member of a species is exactly the same by any means, population genetics, genes influence blood groups, genes influence enzymes, enzyme polymorphism, polymorphic = more than one allele at the frequency greater than if it was a mutation, dna sequence polymorphism. 19. 3 five agents responsible for evolutionary change: mutation can change allele frequencies, makes evolution possible, gene flow, movement of alleles from one population to another, ex: emigration; pollen, nonrandom mating shifts, assortative mating. 19. 4 selection can act on traits affected by many genes: disruptive selection removes intermediate phenotypes, example: large beaks and small beaks; mid sized beaks would be a disadvantage for both, directional selection eliminates phenotypes on one end of a range, eliminate one extreme, stabilizing selection favors individuals with intermediate phenotypes.
