Question

What Conditions increase the strength if genetic drift ?

Answer 1

Genetic drift is a mechanism in which allelic frequencies are changed by chance or we can say by sampling error. Size of the population has major influence on genetic drift. Effect of genetic drift is stronger in smaller population size. As the population size increases generation after generation, the effect of genetic drift is decreases.

Here fluctuation in allelic frequency (harmful or useful) is by chance or random event. In large population this effect is reduced generation after generation due to natural selection (alleles which are more stable and suitable for the current habitat are selected and fixed in population). However in smaller population genetic drift is stronger because number of individuals is less in smaller population. So the chance of selection is also less.

Hence smaller population size increases the strength of genetic drift.