A situation in which the allele frequencies change as a result of the migration of a small subgroup of individuals is know as the

a) genetic eqilibrium
b) founder effect
c) bottleneck effetc
d)hardy-weinberg principle

you can have just about every answer you can think of

increases the risk of extinction 

explanation:

the answer is that if the species suffers from the disease, there is nothing stronger than the others, so it is possible to remove wholeness. an example of this is hunger in irish potatoes, which has a deadly disease bearish part of all potato harvest masses. pretty much ruins the land of crops.