Question

bird beak variation
bird beak size is often related to the type of food the bird eats and the size of the food source. some birds with stout beaks (e.g., finches) with large beaks are better - able to eat larger seeds, while birds with small beaks typically eat smaller seeds.
an environmental change occurred that resulted in a reduction in one type of food, namely small seeds. the change caused a shift in the distribution of beak sizes observed. the graph shows the distribution of birds of various beak sizes before and after the change.

which statement best describes what happened to the birds with smaller beaks?
a. the environment selected for them, increasing the competition for small seeds and reducing the number of birds with small beaks in the population.
b. the environment selected for them, decreasing the competition for small seeds and increasing the number of birds with small beaks in the population.
c. the environment selected against them, increasing the competition for small seeds and reducing the number of birds with small beaks in the population.
d. the environment selected against them, decreasing the competition for small seeds and increasing the number of birds with small beaks in the population.

Explanation:

The shift in the distribution of beak - sizes indicates that the environment selected against birds with smaller beaks. This would increase competition for small seeds among the remaining birds with small beaks and reduce the number of birds with small beaks in the population.

Answer:

C. The environment selected against them, increasing the competition for small seeds and reducing the number of birds with small beaks in the population.