Question

What is genetic drift and what is the evidence for it?

Answer 1

Genetic drift is change in distribution of allele in a small population .

Explanation:

In a population alleles express in multiple. That is large number of the population is with multiple allele expression.
But in a small population due to inbreeding or due to environmental factors like loss of habitat the distribution of particular allele changes.
This may lead to extinction of a species in small population.
Example is Asiatic lion. About 400 lions are surviving in Gujrat India. There is no chance of intermixing genetic pool in this small population. No wonder the population is with similar genetic makeup. Genetic drift will dwindle the population easily.