Question

How did the abundance of rain in 1983 affect the bird population and their beaks in 1984?

A) The bird population would remain unchanged, as rain does not impact their survival or beak types.
B) Small beaks would become more prevalent due to the regrowth of small seeds after the rain returned, alongside the continued presence of large beaks.
C) New types of beaks, not seen before, would emerge as a result of the change in rain conditions.
D) The bird population with beaks adapted to drought would increase during the abundance of rain.
E) None of the above.

Answer 1

The abundance of rain in 1983 would lead to regrowth of small seeds, allowing birds with small beaks to survive alongside birds with large beaks. This offers a good example of natural selection, where beak size adapts to the available food sources. Option b is the answer.

Step-by-step explanation:

The question explores the effects of environmental changes, specifically rainfall, on bird beak size and population through natural selection. During a drought on the Galápagos, as observed by the Grants, the scarcity of small seeds meant that finches with larger beaks, capable of eating larger seeds, had a survival advantage. This natural selection resulted in an increase in average beak size within the population. Following this logic, if an abundance of rain occurred in 1983, it would likely cause regrowth of small seeds, which birds with smaller beaks are able to eat, in addition to the large seeds.

This would allow both large-beaked and small-beaked birds to survive and reproduce.

Therefore, answer B is correct, stating that small beaks would become more prevalent due to the regrowth of small seeds after the rain returned, alongside the continued presence of large beaks. This example showcases the principles of evolution by natural selection based on changes in the environment that affect food availability.