Differentiation

Differentiation generally considers the accumulation of genetic differences between populations or species but can be applied more broadly to the diversification of genes, organisms, and populations. This article examines how elementary evolutionary and ecological processes lead to differentiation in both the narrow and broad senses and introduces successively more complex processes involved in differentiation. Most mutations are selectively neutral and neutral evolution can be considered the default process of genomic change, with natural selection being measurable from changes in allele frequencies that lead to deviation from neutrality. While the basic tenets of genetic differentiation are well established, the advent of new genomic technologies and associated computational tools have provided unprecedented insights into the mechanism of genetic differentiation and how these might lead to the formation of species. Recent work has highlighted in particular the importance of genetic admixture events and genomic interactions in shaping the process of differentiation.