Chapter 25 - Population Genetics

Chapter 25 - Population Genetics - Chapter 25 Population...

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Population Genetics Population genetics study of genetic variation in populations and how it changes over time - investigate patterns of genetic variation or genetic structure within and among groups of interbreeding individuals allele frequencies in population gene pools vary in space and time - population group of individuals sharing a common set of genes that lives in the same geographic area and actually or potentially interbreeds o gene pool constitute all alleles shared by population o dynamic – expand and contract through changes in birth and death rates, migration, or contact with other populations Hardy-Weinberg Law describes relationship between allele frequencies and genotype frequencies in an ideal population - Hardy-Weinberg law describes what happens to alleles and genotypes in an ‘ideal’ population that is infinitely large and random mating, and that is not subject to any evolutionary forces such as mutation, migration, or selection - model makes two predictions o frequencies of alleles in the gene pool do not change over time o if two alleles at a locus are considered, then after one generation of random mating the frequencies AA:Aa:aa in population can be calculated p 2 + 2pq + q 2 = 1 p = frequency of allele A q = frequency of allele a population meets criteria, said to be in equilibrium - assumptions taken to work Hardy-Weinberg law o individuals of all genotypes have equal rates of survival and equal reproductive success there is no selection o no new alleles are created or converted from one allele into another by mutation o individuals do not migrate into or out of population o population is infinitely large population is large enough that sampling errors and other random effects are negligible o individuals in population mate randomly - three important consequences of H-W law o shows that dominant traits do not necessarily increase from one generation to the next o demonstrates that genetic variability can be maintained in population since, once established in an ideal population, allele frequencies remain unchanged o
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Chapter 25 - Population Genetics - Chapter 25 Population...

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