1. 25.1 Genotypic and Allelic Frequencies Are Used to Describe the Gene Pool Of a Population Calculating genotypic frequencies F = No.AA individuals/N N: total no. of individuals F: frequency of AA alleles. Calculating allelic frequencies Frquency of an allele = No. copies of the alleles/No. copies of all alleles at the locus in a population.

2. Hardy-Weinberg Law Assumption: population is large, randomly mating, not affected by mutation, migration, or natural selection. Prediction 1: the allelic frequencies of a population do not change. Prediction 2: the genotypic frquencies stabilize. 25.2 The Hardy-Winberg Law Describes the Effect of Reproduction on Genotypic and Allelic Frequencies

3. p + q = 1 p 2 + 2pg + q 2 = 1 P 2: homozygous dominant allele pair frequency. Q 2 :homozygous recessive allele pair frequency. 2pq: heterozygous allele frequency. Genotypic frequencies at H-W equilibrium

5. Concept Check 1 What is the expected frequency of heterozygotes in a population with allelic frequency X and Y that is in H-W? a.X + Y b.XY c.2XY d.(X- Y) 2

6. Concept Check 1 What is the expected frequency of heterozygotes in a population with allelic frequency X and Y that is in H-W? a.X + Y b.XY c.2XY d.(X- Y) 2

7. 25.3 Nonrandom Mating Affects the Genotypic Frequencies of a Population Positive assortative mating: a tendency of like individuals to mate. Negative assortative mating: A tendency of unlike individuals to mate.

8. Inbreeding Increases frequency of homozygotes in population Rate is affected by how closely related mating pairs are

11. Concept Check 2 What is the effect of outcrossing on a population? a.Allelic frequency changes in the population. b.More heterozygotes will be produced in the population. c.Fewer heterozygotes will be produced. d.It will reach the H-W equilibrium

12. Concept Check 2 What is the effect of outcrossing on a population? a.Allelic frequency changes in the population. b.More heterozygotes will be produced in the population. c.Fewer heterozygotes will be produced. d.It will reach the H-W equilibrium

13. 25.4 Several Evolutionary Forces Potentially Cause Changes in Allelic Frequencies Mutation Migration Genetic Drift Founder effect Genetic bottle neck Natural selection