Refer to the figure.
The figures show the distribution of beak sizes in Galápagos medium ground finches (Geospiza fortis) before and after a year of extreme drought that reduced the availability of seed types most easily accessed by birds with pre-drought bills. Which of the following statements is true?
A) Between 1976 and 1978, mean beak depth increased by approximately 30%, which is an example of disruptive selection.
B) Between 1976 and 1978, mean beak depth increased by approximately 10%, which is an example of directional selection.
C) Between 1976 and 1978, mean beak depth increased by approximately 10%, which is an example of stabilizing selection.
D) Between 1976 and 1978, mean beak depth did not change significantly, but variance increased, as expected for disruptive selection.

Question

Refer to the figure.
 The figures show the distribution of beak sizes in Galápagos medium ground finches (Geospiza fortis) before and after a year of extreme drought that reduced the availability of seed types most easily accessed by birds with pre-drought bills. Which of the following statements is true?
A) Between 1976 and 1978, mean beak depth increased by approximately 30%, which is an example of disruptive selection. 
B) Between 1976 and 1978, mean beak depth increased by approximately 10%, which is an example of directional selection. 
C) Between 1976 and 1978, mean beak depth increased by approximately 10%, which is an example of stabilizing selection. 
D) Between 1976 and 1978, mean beak depth did not change significantly, but variance increased, as expected for disruptive selection.

Quizplus · Accepted Answer

The Answer of Refer to the figure.
 The figures show the distribution of beak sizes in Galápagos medium ground finches (Geospiza fortis) before and after a year of extreme drought that reduced the availability of seed types most easily accessed by birds with pre-drought bills. Which of the following statements is true?
A) Between 1976 and 1978, mean beak depth increased by approximately 30%, which is an example of disruptive selection. 
B) Between 1976 and 1978, mean beak depth increased by approximately 10%, which is an example of directional selection. 
C) Between 1976 and 1978, mean beak depth increased by approximately 10%, which is an example of stabilizing selection. 
D) Between 1976 and 1978, mean beak depth did not change significantly, but variance increased, as expected for disruptive selection.

Refer to the Figure