California salamanders belong to the group of terrestrial amphibians.
The original population of California salamanders lived in a forested region in northern California. About 10 million years ago, two separate populations, A and B, began moving away from the original population.
• Population A moved along the Californian coast, to the west of the Great Central Valley.
• Population B moved to the east of the Great Central Valley.
These two populations now occur close to one another in southern California.
Fig. 8.1 shows the migratory routes followed by populations A and B.
(main)[5]
Salamanders from population A rarely interbreed with salamanders of population B. If interbreeding does occur, the offspring are infertile.
Suggest and explain the sequence of events that has caused these two populations to become reproductively isolated from each other.
Worked solution & mark scheme
This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Geographical isolation brought about during migration” …