In southern Arizona, in the Chiricahue Mountains, there are species of toads that live aciya
the top of individual mountains. Because these toads have adapted to the elevation as tops
of these mountains, they have become reproductively isolated from all other species of toad
within that mountain range.

Geographic isolation

Explanation:

Geographic isolation can be described as a term that describes the model of speciation in which a biological population becomes isolated from other members of the population and can no longer have gene flow with them.

The same scenario of gene isolation is occurring in the species of taods which live at the top of the mountains in southern Arizona. This population has become reproductively isolated fro all other species of toads within the mountain range.