Bio; Lecture 10; Population Genetics

Bio; Lecture 10; Population Genetics - Principles of...

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Principles of Biology 2 BioU103 1-31-07 Causes of Microevolution o Natural Selection Variation within a population allows some individuals to be better at survival and reproducing—enabling them to spread their genes more. Natural selection is a violation of the conditions of the Hardy Weinberg equilibrium HW assumes that all individuals have equal reproductive success However, because of natural selection, some alleles are passed on to the next generation in frequencies disproportionate to their frequencies in the previous generation o In general, natural selection tends to reduce genetic diversity Natural selection tends to make the genetic structure of the population more homogeneous. However, without genetic variation, natural selection cannot occur. Genetic variation is the substrate for natural selection Genetic variation is increased by: Meiosis o Crossing over o Independent assortment of homologous chromosomes o Segregation of homologous pairs o Random fertilization Mutations o Must occur in gametes in the cell in order to affect evolution Migration o Mutation : change in an organism’s DNA A new mutation that is transmitted in gametes can immediately change the gene pool of a population by substituting the mutated allele for the older allele For any single locus, mutation alone does not have much quantitative effect on a large population n a single generation An individual mutant allele may have greater impacts later through increases in its relative frequencies as a result of natural selection
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This note was uploaded on 05/26/2008 for the course BIO 103 taught by Professor Potts-santone during the Spring '07 term at Northeastern.

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Bio; Lecture 10; Population Genetics - Principles of...

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