What is speciation?
The Speciation is the process by which different species emerge from a common ancestor species. The Speciation generally begins when populations of the same species become geographically isolated, that is when they are separated by some physical barrier that disallows crossing between individuals from one population and individuals of another population.
A Group that for a long time is kept under geographical isolation tends to accumulate different phenotypical characteristics from each other by means of genetic variability (mutations and recombination) and natural selection and when those differences reach a point that makes the crossing of individuals of one group with individuals of the other group not possible or the generation of fertile offspring no longer happens it is said that speciation has occurred.