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.