A group of researchers spent 8 years in the Galapagos Islands measuring beaks, observing feeding behavior, and measuring rainfall in a population of a particular species of Darwin's finch. They found that this species eats only small seeds and that its beak enables the bird to crack and eat such seeds quickly and efficiently. The beak-size data are in the table below.
Develop a hypothesis that explains what caused beak size to increase in dry years. Your hypothesis should specify how the fates of individuals determine changes in the population.
|
Year
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
|
Rainfall
|
normal
|
normal
|
normal
|
very low
|
normal
|
normal
|
normal
|
normal
|
|
Average beak size
|
10.1
|
10.3
|
10.2
|
12.1
|
12.5
|
10.1
|
10.0
|
10.1
|