Speziation
Speciation is the evolutionary process by which new biological species arise. It is the central question of evolutionary biology, and its occurrence is the linchpin of evolutionary theory. Speciation typically occurs when a population is divided into two or more geographically isolated groups. Over time, these isolated populations accumulate genetic differences due to mutation, natural selection, and genetic drift. Eventually, these genetic differences become so substantial that individuals from the different populations can no longer interbreed and produce fertile offspring, at which point they are considered distinct species.
There are several recognized mechanisms of speciation. Allopatric speciation is the most common and occurs when