BIO 202 Study Guide - Quiz Guide: Genotype Frequency, Allele Frequency, Gene Pool
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19 Feb 2019
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Ch 19: Evolutionary Change in Populations
Evolution Occurs in Populations, not individuals
• Population genetics: study of genetic variability within population and evolutionary
forces acting on it
o Can estimate amount of observed variation that’s genetic
▪ Amount of observed variation is determined by the number, frequency,
and kinds of alleles in a population
Genotype, Phenotype, and Allele Frequencies
• Gene pool: all alleles for all loci present in a population
o Diploid: 2 alleles at each genetic locus
o Each individual has different subset of alleles in gene pool
• Genotype frequency: proportion of particular genotype in a population
o Represented as decimal fraction
▪ All genotype frequencies add to equal 1.0
• Example: frequency of AA = 0.60, frequency of Aa = 0.30,
frequency of aa = 0.10
• Phenotype frequency: proportion of particular phenotype in a population
o If 2 alleles are dominant and recessive, the dominant phenotype is the sum of 2
genotypes, AA and Aa
▪ Using above example, the frequency of the dominant phenotype would be
0.60 + 0.30 = 0.90 (90% of population has dominant phenotype)
• Allele frequency: proportion of specific allele in particular population