ch 20 pt 3 hardy-weinberg

genotype

genetic constitution of an individual, pairing of alleles at a single position in the DNA

phenotype

physical characteristics or traits of an individual

Godfrey H. Hardy

• English mathematician

  • published his solution to the “very simple” biologist problem in 1908

  • known as Hardy’s law until 1943

Wilhelm Weinberg

• German obstetrician

  • delivered the idea in 1908 before the Association for Patriotic Natural History in Wurttemberg

Godfrey H. Hardy and Wilhelm Weinberg

“allele and genotype frequencies tend to remain constant in the absence of disturbing forces”

• separately developed mathematical models for quantifying whether a population is undergoing evolution

• hypothesis that a population is in Hardy-Weinberg Equilibrium (HWE), is considered the null hypothesis

• if a population is in HWE, then genotype frequencies should be predictable based on the allele frequencies

conditions that must be met for populations to be in Hardy-Weinberg Equilibrium (HWE)

1. no differential reproductive success among individuals

2. no migration

3. no mutation

4. random mating

5. large enough population size

thus, if in HWE, then the population is not evolving

if populations are in HWE

• genotype frequencies should be predictable based on the allele frequencies

• the predicted or expected number for each genotype = the observed or measured number for each genotype