The original population of salamanders migrated southward from the north of California. They avoided the Central Valley because it was too dry and hot for them to live there. As they moved south, the eastern and western salamander populations evolved and by the time they got together again in Southern California, they could no longer interbreed and had become two new species of salamanders.

Identify the main mode of isolation of eastern and western salamanders in Southern California.

A. The populations evolved separately because they were temporally isolated.
B. The populations evolved separately because they were behaviorally isolated.
C. The populations evolved separately because they were geographically isolated.
D. The populations evolved separately because they were reproductively isolated.

Geographical isolation is a term that refers to a population of plants or animals that are separated from mating with the other organisms of the same species.

This is due to the separation of the organism because they are geographically isolated from one another. Here some members of the same species are isolated from the other members of the same species.

The eastern and western salamanders are isolated by each other because of geographical isolation.