Question

A certain boney fish species is an omnivore and exists only in an isolated lake. Which of the would MOST LIKELY result in the natural selection of this fish species over others after ten thousand years?
Responses
A The lake dries up rapidly due to changes in the environment eliminating all fish living in the lake.The lake dries up rapidly due to changes in the environment eliminating all fish living in the lake.
B The fish species produces many offspring with many unique traits, and the food availability remains constant.The fish species produces many offspring with many unique traits, and the food availability remains constant.
C The fish species experiences external or internal factors greatly limiting reproduction, and the food availability changes quickly. The fish species experiences external or internal factors greatly limiting reproduction, and the food availability changes quickly.
D The fish species produces few offspring with no unique traits, and the food availability greatly decreases.

Answer 1

C

Explanation: rapid changes in food availability create strong selective pressures so individuals with heritable traits that allow them to survive and reproduce (e.g., omnivorous diet flexibility) will be favored. Limiting factors on reproduction intensify differential survival. A and D lead toward extinction, and B has variation but a constant environment so little directional selection.