Final answer:
No, the statement is false. When marine sticklebacks mate with freshwater sticklebacks, the trait of lightly armoured fish is recessive, not dominant.
Step-by-step explanation:
No, the statement is false. In the case of marine sticklebacks mating with freshwater sticklebacks, the trait of lightly armoured fish is recessive, not dominant. This means that when a marine stickleback mates with a freshwater stickleback, the offspring will inherit the dominant trait of heavily armoured fish. The offspring will be heavily armoured, not lightly armoured. This can be explained by understanding the principles of dominant and recessive traits in genetics, where the dominant trait masks the expression of the recessive trait.