A population of 10,000 individuals contains a single rare allele 'a'. …

Question

A population of 10,000 individuals contains a single rare allele 'a'. A volcanic event destroys all but 50 randomly chosen individuals; allele frequencies in the survivors differ sharply from the original population. The resulting shift is best described as:

Accepted Answer

B. {'text': 'A bottleneck event in genetic drift, after random destruction of most members', 'label': 'B'}

When a catastrophe randomly reduces a population so that allele frequencies in the survivors differ sharply from the original gene pool, the chance change in allele frequency is genetic drift acting via a bottleneck. The founder effect specifically refers to a small group establishing a new population in a different area.

Answer

{'text': 'The founder effect, with the survivors colonising a new geographic area', 'label': 'A'}

Answer

{'text': 'Directional natural selection imposed on the population by the volcanic event', 'label': 'C'}

Answer

{'text': 'Gene flow into the surviving population from a neighbouring source population', 'label': 'D'}