CHEM 112 Lecture Notes - Genetic Drift, Lake Tanganyika, Zebra Finch
15 Jan 2013
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These individuals will then contribute more offspring to the next generation. Directional selection produced resistance to tetrodotoxin (ttx) in garter snakes: disruptive selection favors individuals that vary in both directions from the mean of the population. Individuals at both extremes of a population are simultaneously favored. Ex: the bill sizes of black-bellied seedcrackers. Experiment: hypothesis: having well-developed ornamental traits signals vigor and health, carotenoids are antioxidants and part of the immune system. Males in good health will have brighter bills. Zebra finch bills are bright red because of carotenoids in their diet. because they need to allocate fewer carotenoids to immune function. Zebra finch males were fed diets with and without carotenoids. 22. 4 how is genetic variation maintained within populations: genetic drift, stabilizing selection, and directional selection all tend to reduce genetic variation within an animal population, however, most species have considerable genetic variation. Things that help maintain genetic variation: sexual reproduction. Populations in different (varying) environments frequency-dependent selection.
