Which best describes biogeographic isolation?

Which best describes biogeographic isolation?

A. It always leads to the formation of new species.
B. It cannot lead to evolution.
C. It is a mechanism for evolution.
D. It occurs only through geographic forces.

Answer: C. It is a mechanism for evolution.

Biogeographic isolation is an interesting mechanism of evolution. It happens when the populations of the very same species become physically isolated due to geographical barriers in the form of mountains, rivers, or oceans, thereby limiting the gene movement between them. Over time, the resulting isolation may lead to the development of genetic divergence as the different populations independently accumulate differences due to mutation and natural selection, as well as genetic drift. Though it has the capacity of providing the basis for the development of new species, the final product of speciation is not certain; speciation depends on numerous factors, among them the time span for the isolation. Biogeographic isolation is therefore an important process of evolution, but not the only trigger for speciation.