07-02-08

07-02-08 - 07-02-08 A. The Preservation of Genetic...

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07-02-08 A. The Preservation of Genetic Variation a. Various mechanisms help to preserve genetic variation in a population b. Diploidy: Maintains genetic variation in the form of hidden recessive alleles c. Balancing selection: occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a population B. Heterozygote Advantage a. Some individuals who are heterozygous at a particular locus have a greater fitness than homozygotes b. Sickle-cell allele: causes mutations in hemoglobin, but also confers malaria resistance c. Ex. Heterozygous with the sickle-cell allele will live while the ppl with non-sickle allele in sub-Saharan Africa will die of malaria, but those with both sickle alleles will die of sickle-cell anemia C. Sexual Selection a. Type of selection that favors a trait giving an individual a competitive edge in attracting or keeping a mate b. Can result in sexual dimorphism (difference in look of the two sexes) c. Intrasexual selection : direct competition among individuals of one sex for mates of the opposite sex i. Ex. Rams butting horns, deer hitting horns, etc… d.
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This note was uploaded on 07/21/2008 for the course BIOL 1202 taught by Professor Gregg during the Summer '08 term at LSU.

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07-02-08 - 07-02-08 A. The Preservation of Genetic...

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