Could emigration or immigration have played a major role in determining the size of the reindeer population? Explain. Think about where these reindeer were and whether they could swim that far

Yes.

Explanation:

Yes, emigration or immigration have played a major role in determining the size of the reindeer  population in specific area because immigration is done by the animals in search of food. The animals moves from one region to another in search of food so due to this movement the population of reindeer decreases in that specific area. Reindeer are good swimmers so due to this ability they cross the vast Yukon River which is half mile wide.

answer: the answer is b

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).