Question

The bar graph shows the average beak depth (distance from the top of the beak to the bottom) of a population of finches. The data were collected in 1976 and in 1978, after a drought occurred in 1977 in the area.







Which factor BEST describes the change in this population of finches?

Select {responseValue}
An increase in resource availability

Select {responseValue}
A change in the reproductive success of one individual bird

Select {responseValue}
A decrease in fitness that increased survival rates

Select {responseValue}
A change in phenotype distribution because of an environmental factor

Answer 1

A change in phenotype distribution because of an environmental factor

Explanation: The 1977 drought changed available food resources, so birds with deeper beaks had higher survival/reproductive success. This environmental selection shifted the population's beak-depth distribution.