Question

Darwin observed finches with many different shapes and sizes of beaks on the Galapagos Islands. He noticed that these finches lived in different areas of islands and on different islands that had different food sources. The beaks of finches that lived in a particular area were adapted better for eating the food available in that area. For example, the medium ground finches were well adapted for eating small seeds, an abundant food source on the island. During a severe drought, many plants that produced the small seeds died, limiting small seeds available for food. Another food source for the birds was a larger, harder seed produced by a different plant.

What do you predict would occur? Choose all THREE that apply.
Responses
A Some of the medium ground finches left to find food sources in other places.Some of the medium ground finches left to find food sources in other places.
B The finches all died.The finches all died.
C Birds with thicker beaks were able to eat the larger seeds and had less competition for food allowing them to survive and reproduce.Birds with thicker beaks were able to eat the larger seeds and had less competition for food allowing them to survive and reproduce.
D The medium ground finches developed thicker, larger beaks.The medium ground finches developed thicker, larger beaks.
E The medium ground finches competed for the limited number of small seeds and many of them died.

Answer 1

A, C, and D are the most likely outcomes that would occur. The medium ground finches that were not well adapted to eating the larger, harder seeds would have to find other food sources, so some of them would leave to find food sources in other places. The birds with thicker beaks would be able to eat the larger seeds and would have less competition for food, allowing them to survive and reproduce. Over time, the medium ground finches that had thicker, larger beaks would be more likely to survive and reproduce, passing on their traits to their offspring. Therefore, the medium ground finches would be expected to develop thicker, larger beaks over time.