Genetic divergence

[1] In some cases, subpopulations cover living in ecologically distinct peripheral environments can exhibit genetic divergence from the remainder of a population, especially where the range of a population is very large (see parapatric speciation).

The genetic differences among divergent populations can involve silent mutations (that have no effect on the phenotype) or give rise to significant morphological and/or physiological changes.

[2] One possible cause of genetic divergence is the founder effect, which is when a few individuals become isolated from their original population.

The bottleneck effect is when an event, such as a natural disaster, causes a large portion of the population to die.

By chance, certain genetic patterns will be overrepresented in the remaining population, which is similar to what happens with the founder effect.

[6] Disruptive selection is seen in the bimodal population of Darwin's finches, Geospiza fortis.