What are Allopatric species, Sympatric species and Neontological species?

Allopatric species are those that have evolved in the course of time due to geographical separation between the two populations of the same species. This geographical isolation prevents mating between the two organism of same species. As a result, there is no gene flow in the population. So, ultimately these organisms speciate to give rise to new species.

Sympatric species are those that have evolved from the ancestors that are existing in the same geographical area for a long period of time. There is no reproductive isolation of species is observed in sympatric speciation.

Neontological species- Those species which are present  in the  living world are known as neontological species.