After the glacial retreat at the end of the last ice age, some three-spine stickleback fish (Gasterosteus aculeatus) were isolated in small lakes. A mutation occurred in these fish that resulted in...

After the glacial retreat at the end of the last ice age, some three-spine stickleback fish (Gasterosteus aculeatus) were isolated in small lakes. A mutation occurred in these fish that resulted in the loss of pelvic spines. Today, all freshwater sticklebacks lack pelvic spines, but are still classified as members of the same species as marine sticklebacks.

Scientists collected sticklebacks from both marine and freshwater environments and placed them together in a controlled environment. Which of the following statements describes the effect of the mutation on their ability to interbreed?

A - They should be able to interbreed and produce fertile offspring

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B - They will not be able to interbreed and produce offspring because of hybrid breakdown.

C - They will not be able to interbreed and produce offspring because of mechanical isolation.

D - They should be able to interbreed and produce offspring, but the offspring may experience reduced hybrid fertility.