Question

Genetics Question: Explain the assumptions that are made using HWE that would be indicated if our data do not reject the null. What are the possible reasons/conditions the null hypothesis would be rejected by data.

Answer 1

ASSUMPTIONS OF HARDY WEINBERG EQUILIBRIUM

• Alarge random mating population in the absence of migration , mutation and selection is stable with respect to both gene and genotype frequency.
• The genotype frequencies in the progeny produced by random mating among the parents are determined solely by the gene frequency among parents.
• The frequency of homozygotes equals the square of the relevant gene frequency.
• The frequency of heterozygotes equals twice the product of the homozygotes corresponds to the square of gametic frequencies.
• Such population is said to be genetic equilibrium for a singlee autosomal locus , the hardy weinberg genotype frequencies are established by one generation of random mating irrespective of the genotype frequencies among parents.
• For a single locus with two alleles the maximum frequency of heterozygote will be 0.5 then p=q=0.5

Assumptions of HWE that would indicate if our data do not reject the null

• If data are available for a locus where all the genotypes are recognizable then the observed genoytype frequencies are used to test for HWE.
• According to HW law, the genotype frequencies of progenies are determined from the gene frequencies of their parents.
• If the population is in HWE, frequencies same in progenies as in parents.
• From the gene frequency expected genotype frequencies are calculated. From them the expected numbers are arrived. The agreement between the expected and observed numbers is tested using Chi square test.
• If calculated value > table value . The discrepancy is significant and the given population don't evolved by chance in the sampling.
• If we do not reject null, we can conclude that the genotype frequencies in this population is significantly different than what would be expected if the population is in HWE.

Possible conditions the null hypothesis would be rejected are:-  

• If the given population evolved by chance in the sampling.
• if mutation, migration, selection and genetic drift resulted.