When only a few individuals survive unfavorable times, thereby losing the majority of genotypes in the next generation, is called/?

Answer;

A bottleneck effect

Explanation;

When only a few individuals survive unfavorable times, thereby losing the majority of genotypes in the next generation, it is called a bottleneck effect.

It occurs when there is a disaster of some sort that reduces a population to a small handful, which rarely represents the actual genetic makeup of the initial population.