Question

How would a drastic reduction in a population’s size affect that population’s gene pool or genetic variability?

Answer 1

A drastic reduction in the population size caused by a random but major catastrophic event could have the chances to lead to a bottleneck effect.

Consequently, a reduced gene pool size - and reduction in diversity (most of the times) might lead the suffered population to a genetic drift. At this particular point, extinction could occur due to chance variation but recovery may also occur if evolution is accelerated. Genetic diversity, however, remains low even if recovery happens. Thank you.