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Unit 14

Population Genetics, Natural Selection

Evolution changes in gene frequencies in populations overtime
Evolutionary Fitness the ability of an organism or allele to survive and reproduce to other individuals or alleles within the population
Population A group of organisms that interbreed such as to produce viable offspring
Gene Frequency Numeric rate at which a gene occurs in a gene pool, relative to the other alleles in its gene pair
Genetic Diversity The variety of genes and genotypes in a gene pool
Genetic Drift Changes in gene frequencies owing to random factors
Gene Flow Movement of genes into or out of a population resulting from migration
Mutation Alteration to the nucleotide sequence of a gene
Directional Selection genetically-related change in mean overtime follows a progressive trend. selective pressure moves population from one average to another
Stabilizing Selection No genetically-related change in population mean overtime. Selective pressure keeps population centered around an average.
Disruptive Selection Genetically-related change in mean overtime that produces two "means" (modes). Selective pressure splits population around two "averages" or modes. Leads to Speciation
How to calculate gene frequencies Example A = 11, 11/20 = .55 percent a = 9, 9/20 = .45 percent 11+9 = 20



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