After the drought of 1977, researchers hypothesised 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 Tribulus 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

When a reliable food source is provided, natural selection pressure decreases, and the survival advantage of having a specific beak type diminishes. As a result, there may be a higher variation in beak size and shape as there is no strong pressure to maintain a specific type. Therefore, increased variation in beak size and shape over time is the most likely to occur. Options A and B are unlikely to happen as they require natural selection pressure to work towards a specific direction constantly, and the provision of reliable food sources results in the opposite. Option D is also unlikely as some variation is expected to occur over time due to genetic drift and mutation.

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