XXI.5 Various types of speciations can be sorted according to the type of reproductive barrier
If the separation and differentiation of a new species was caused primarily by spatial and temporal separation of two subpopulations, then this speciation is called allopatric. In principle, allopatric speciation could be divided into several types according to the process that caused the phenotype differentiation of the two parts of the population (drift, selection, drive, draft, etc.); however, this is mostly not done. Of course, the situation is different when the separation of the parent species is caused by internal reproduction barriers. A number of different types of speciation can be distinguished according to the character of these barriers.