Question

In the late 1970s, the Galapagos Islands experienced a severe drought that sharply reduced the finch population living there. It was discovered that only finches with large, thick beaks survived the drought as they subsisted on cactus, which are drought-tolerant plants.
In the early 1980s, the Galapagos Islands underwent an El Nino event that led to higher annual levels of precipitation than normal. This climate event occurred just a few years after the drought. The increase in rainfall led to a dramatic increase in the growth of seed-producing plants, which led to an abundance of foods for seed-eating finches, which have small, short beaks.
The increase in rainfall also decreased the availability of cactuses on the islands. Which of the following would you predict occurred in the finch population as a result of the second change in climate?
A. The variety present in the finch population did not change due to changes in climate.
B. The population of short-beaked finches increased while the population of large beaked birds decreased.
C. The large-beaked finches increased in number while the short-beaked finches decreased in number.
D. The number of finches of each type both decreased due to the change in the climate.
E. The large-beaked finches hybridized with the short-beaked finches.

Answer 1

Hint:The finches living in the Galapagos Islands were studied by Darwin due to which they are known as the Darwin finches. Galapagos Islands had a wide variety of small blackbirds that differed in the shape of the beaks and the feeding habits.

Complete answer:
Darwin finches are an example of natural selection. As per Darwin’s concept of Natural selection, he stated that as a struggle for existence only those organisms can survive that have suitable or favorable variations present in them. These variations help them to adapt to the existing conditions of the environment. In other words, it can be said that the struggle to exist causes the survival of the fittest organisms. This means that natural selection causes those organisms to be favored that are fit or adapted to survive. Along with this a reproductive age and a particular environment are required to produce the offspring.
Therefore, when the Galapagos Islands underwent the El Nino event, the short-beaked finches predominated. This is because they were able to survive but the population of the short-beaked finches declined. This is because they were not able to adapt to environmental changes.
Thus, based on the above information we can conclude that the population of short-beaked finches increased while the population of large beaked birds decreased in the finch population as a result of the second change in the climate.

Hence, the correct answer is an option (B).

Note: The Darwin finches are an example of adaptive radiation. These varieties evolved from the original seed-eating ancestor birds that were found in South America. Some of these birds flew to the Galapagos Islands and adapted to thrive in the environment and developed different beaks and feeding habits.