Question

Which of these statements presents the most accurate prediction of what will happen to this fish population?

A group of small fish lives in a lake with a uniformly light-brown sandy bottom. Most of the fish are light brown, but about 10% are mottled. This fish species is often prey for large birds that live on the shore. A construction company dumps a load of gravel in the bottom of the lake, giving it a mottled appearance.
A. As the mottled fish are eaten, more will be produced to fill the gap.
B. In two generations, all the fish will be mottled.
C. There is no way to predict the result.
D. The proportion of mottled fish will increase over time.

Answer 1

D. The proportion of mottled fish will increase over time.

Step-by-step explanation:

In a lake with mottled appearance mottled fish will have advantage over the light brown fishes because light fishes would be easy to be seen by predators.

The proportion of mottled fish will increase over time because of the natural selection. Natural selection is evolutionary mechanism which changes the frequency of a certain allele (consequently, gene and phenotype) by favouring traits (structures, behavior) of an organism that help him survive and reproduce. In the example, above, mottled fish have mottled phenotype that help them survive and reproduce so it will be favorable trait by natural selection.