Two species of garter snake in the genus Thamnophis originated from a single ancestor. These two species live in the same geographic area, however, one lives in arid land and the other lives in water. Whhat identifies the cause of speciation between these two garter snakes?

Habitat isolation is responsible for causing speciation between the two species of garter snakes.

Explanation:

Habitat isolation is a type of isolation in which two species are barred from mating or interbreeding due to the presence of physical barriers between them such as mountains, rivers, etc.Habitat isolation only can happen if two species occupy different habitats.Example- Gryllus  pennsylvanicus prefer to live in those soil which has less water content like in sandy soil  & Grylus firmus prefers to live in soil rich in water moisture i.e. loamy soil