Science 51

Evolution is a process by which the frequencies of various traits (alleles) within a population change over time. There are numerous factors that affect the rate of evolution, including genetic drift and gene flow. Two scientists discuss the impact of both phenomena on small, insular populations.

Scientist 1

Genetic drift is most influential in the evolution of small populations. Because there are so few individuals in the population, random fluctuations in allele frequencies would severely impact one generation to the next. Gene flow would not be as important, because the populations are isolated. Individuals are unlikely to emigrate or immigrate.

Scientist 2

Gene flow is the most influential factor on the evolution of small populations. Although genetic drift could have a profound impact, gene flow would result in the omission of an allele (lost due to emigration) or the addition of a new allele (gained due to immigration).

There is much evidence that small groups or individuals will travel long distances in search of food, habitat, or mates. Therefore, it is likely that isolated populations without many resources were continually migrating.