BIOL 12100 Lecture Notes - Lecture 15: Melanism, Directional Selection, Stabilizing Selection
31 Aug 2018
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Natural selection guides evolution greatly, always differential survival and reproduction, modes of natural selection, selection acts on phenotypes different phenotypes are favored, directional selection i. ii. iii. Practiced by animal and plant breeders: disruptive, stabilizing, both extreme phenotypes are favored of intermediate. i. ii, reduces the variation. Are going to approach fixation (100%), but it will never reach fixation. Leads to anemia: caused by changes in hemoglobin (hb, sickle shaped cells, red blood cell has about 300 million hb, decreased o2 capacity ii, can clog arteries and veins and cause death, generally: Allele (2*(4)+40)/200=0. 24: malaria- affects red blood cells, frequency of rec allele=q= #alleles/total alleles, thats a lot!, 655,000 people died from malaria last year, however- hb s , heterozygotes are at an advantage, deformed cells prevent parasite from entering. 0: stabilizing selection, both alleles are maintained do to polymorphism.
