Which tests are commonly used to detect bottlenecks by comparing observed heterozygosity to expectation under constant size?

Which tests are commonly used to detect bottlenecks by comparing observed heterozygosity to expectation under constant size?

• A. M-ratio test or Garza-Williamson test.
• B. Tajima's D test alone.
• C. Chi-square test for Hardy-Weinberg equilibrium.
• D. AMOVA test.

Answer: (C)

When a population goes through a bottleneck, the drastic drop in numbers shifts the balance of genetic drift and mutation, often producing a mismatch between what you observe for heterozygosity and what you’d expect if the population had remained at a constant size. The chi-square test for Hardy-Weinberg equilibrium is a direct way to check whether the observed genotype frequencies align with the expected frequencies under random mating and a stable population size. If a bottleneck occurred, you commonly see deviations from those expectations, such as an excess of homozygotes, which the test detects as a significant departure from Hardy-Weinberg proportions. The other options mix in different statistics that don’t target this specific comparison between observed heterozygosity and constant-size expectations as cleanly. So, checking Hardy-Weinberg equilibrium with a chi-square test is the most straightforward way among these choices to flag bottleneck signals through deviations in heterozygosity relative to a constant-size baseline.

When a population goes through a bottleneck, the drastic drop in numbers shifts the balance of genetic drift and mutation, often producing a mismatch between what you observe for heterozygosity and what you’d expect if the population had remained at a constant size. The chi-square test for Hardy-Weinberg equilibrium is a direct way to check whether the observed genotype frequencies align with the expected frequencies under random mating and a stable population size. If a bottleneck occurred, you commonly see deviations from those expectations, such as an excess of homozygotes, which the test detects as a significant departure from Hardy-Weinberg proportions. The other options mix in different statistics that don’t target this specific comparison between observed heterozygosity and constant-size expectations as cleanly. So, checking Hardy-Weinberg equilibrium with a chi-square test is the most straightforward way among these choices to flag bottleneck signals through deviations in heterozygosity relative to a constant-size baseline.