After the drought of 1977, researchers hypothesized that on the Galápagos island Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough T. cistoides fruits. A tourist company sets up reliable feeding stations with a variety of bird seeds (different types and sizes) so that tourists can get a better look at the finches. Which of these events is now most likely to occur to finch beaks on this island?
A) evolution of yet larger, deeper beaks over time, until all birds have relatively large, deep beaks
B) evolution of smaller, pointier beaks over time, until all birds have relatively small, pointy beaks
C) increased variation in beak size and shape over time
D) no change in beak size and shape over time

Question

Quizplus · Accepted Answer

The feeding stations set up by the tourist company provide a consistent source of food for the finches that is not affected by environmental changes such as droughts. This means that the selection pressure for large, deep beaks to crack tough T. cistoides fruits is reduced, allowing for increased variation in beak size and shape over time. This may also result in the evolution of smaller, pointier beaks if they are advantageous for consuming the bird seeds provided at the feeding stations. However, it is unlikely that all birds will evolve to have the same beak size and shape as natural selection can act differently on individual birds depending on their unique genetic makeup and environmental conditions.

After the Drought of 1977, Researchers Hypothesized That on the Galápagos