Peter and Rosemary Grant - Studies on Daphne Major Island

Question

This text is a modified excerpt about the research Peter and Rosemary Grant underwent on the island Daphne Major in the Galapagos.

Daphne Major was a perfect place to perform experiments and study changes within the birds. It was isolated and not inhabited; any changes that were to occur to the land and environment would be due to natural forces with no human destruction. The island provided the best environment to study natural selection; seasons of heavy rain switched to seasons of extended drought. With these environmental changes brought changes in the types of foods available to the birds. This is what the Grants would study for the next few decades of their lives.In 1973 the Grants headed out on what they thought would be a 2 year study on the island of Daphne Major in the Galapagos Islands. There they would study evolution and ultimately determine what drives the formation of new species.There are 13 species of finch that live on the island; five of these are tree finch, one warbler finch, one vegetarian finch, and six species of ground finch. These birds provide a great way to study adaptive radiation. Their beaks are specific to the type of diet that they eat; which in turn is reflective of the food available. During the rainy season of 1977 only 24 millimeters of rain fell. The lack of rain caused major food sources to become scarce, causing the need to find alternative food sources. The smaller, softer seeds ran out, leaving only the larger, tougher seeds. Over the course of 1982-1983, El Nino brought a steady eight months of rain. Daphne Major usually gets two months of rain in the normal rainy season. The excessive rain brought a turnover in the types of vegetation growing on the island. The seeds shifted from large, hard to crack seeds too many different types of small, softer seeds. The finch are easy to catch and provide a good animal to study. The Grants tagged, labeled, measured, and even took blood samples of the birds they were studying. The 2 year study continued through 2012.

Question
Based on the Grant research presented in the original passage and your responses to previous questions, select the graph that best represents the change in average beak size from before 1977 to after 1983.(1 point)
Responses

Answer 1

To select the correct graph that best represents the change in average beak size from before 1977 to after 1983 based on the information provided in the text:

1. Before 1977 (during the normal conditions) - The finches would have exhibited a range of beak sizes, but with the scarcity of smaller, softer seeds caused by the drought in 1977, it is likely that the average beak size would have decreased as the birds that could crack larger, tougher seeds would have had a survival advantage.

2. After 1983 (following the El Niño event) - The situation changed due to the increase in smaller, softer seeds. This shift in food source likely led to an increase in the average beak size since the finches with beaks that could efficiently handle different types of seeds would thrive.

Given these two key points, the graph that shows a decrease in average beak size just before 1977 followed by an increase in average beak size after 1983 would best represent the trends observed during the Grants' study.

If multiple graph options were provided, look for one that shows this trend: a decrease leading into the drought period followed by a subsequent increase showing the finches adapting to the changed environment.