Question

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 were together again in Southern California, they could no longer interbreed and had become two new species of salamanders.



Why did the eastern and western salamander populations evolve separately?

Select {responseValue}
The populations evolved separately because they were temporally isolated.

Select {responseValue}
The populations evolved separately because they were behaviorally isolated.

Select {responseValue}
The populations evolved separately because they were geographically isolated.

Select {responseValue}
The populations evolved separately because they were temporally and geographically isolated.

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Answer 1

Select {responseValue}
The populations evolved separately because they were geographically isolated.

They were separated by the inhospitable Central Valley (a geographic barrier), causing limited or no gene flow and allowing independent evolution (allopatric speciation).