Hardy–Weinberg Equilibrium: Models, Tests, and Applications

All flashcards

Why does the Hardy–Weinberg model assume an effectively infinite population?

To minimize genetic drift, the random change in allele frequencies caused by sampling.

How does inbreeding affect genotype proportions?

It generally increases homozygosity and reduces heterozygosity relative to Hardy–Weinberg expectations.

What does hemizygous mean for a sex-linked locus?

Having one copy of the locus, so genotype frequencies reflect allele frequencies directly.

What is the expected frequency of genotype $A_iA_j$ when there are multiple alleles?

For distinct alleles $i$ and $j$, the expected frequency is $2p_ip_j$.

What does the inbreeding coefficient $F$ measure?

The proportional deficit of observed heterozygosity relative to its Hardy–Weinberg expectation.

Quiz questions

1. When can natural selection change allele frequencies in a population?Answer: When genotypes differ in reproductive success.
2. Which population is most susceptible to genetic drift?Answer: A small population in which allele copies are sampled from few individuals.
3. For a biallelic Hardy–Weinberg goodness-of-fit test with three genotype classes, what is the usual number of degrees of freedom?Answer: One degree of freedom.
4. What does failure to reject a Hardy–Weinberg test’s null hypothesis establish?Answer: It does not prove exact equilibrium; it means the test did not detect a departure.
5. What did Hardy and Weinberg demonstrate about dominance under the model conditions?Answer: Dominance alone does not cause an allele to increase in frequency.