A small population of 500 turtles on an island suddenly suffers a natural disaster leaving only 20 surviving turtles. Before the disaster, the turtles had shells with very different shell patterns. After the disaster, the shells all look very similar. What mechanism can best explain this reduction genetic variation?

(A) Genetic drift
(B) Adaptive radiation
(C) Gene flow
(D) Sexual selection

Genetic drift

Explanation:

This can be explained as a continuous in reduction in allelic frequencies over a short period of time leading to loss of alleles. Loss of alleles can allow for fixation of one allele over a short period of time. When allelic frequencies continue to drift up and down over a short period of time, thing could promote loss of alleles

as resources become scarce because of population growth, the growth decreases after few years due to lack of resources and food.