Geography affects evolution locally, through fragmentation of ecosystems, which results in allopatric speciation. This is a mode of speciation induced when the ancestral population becomes segregated by a geographical barrier. Geography also affects evolution globally through the latitudinal species diversity gradient, which simply means that biodiversity is greatest at the equator, and decreases as latitude increases.

Geographic features and the alteration of these features affect climate and the environment; and the environment, and response to environment is what controls natural selection. The geographical distribution of a species directly influences their ability to survive changes in their environment.