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

Based on the research conducted by Peter and Rosemary Grant on Daphne Major Island, the changes in average beak size of the finches in response to environmental changes can be inferred as follows:

1. Before 1977, during normal rainy seasons, the finches had access to a variety of soft seeds and likely exhibited smaller average beak sizes suited for these types of seeds.
2. During the drought in 1977, the availability of smaller, softer seeds decreased significantly, forcing finches to adapt to eating larger, tougher seeds. This would have likely led to an increase in average beak size during this period as those birds with larger beaks were better suited to crack the tougher seeds.
3. After the excessive rainfall brought by El Niño in 1982-1983, which resulted in the abundance of smaller seeds, one might expect the average beak size to shift back toward smaller sizes if the birds adapted to the new available food sources.

Given this information, the best graph to represent the change in average beak size from before 1977 to after 1983 would likely show a gradual increase in beak size leading up to 1977, a peak or high average after the drought, and then a decrease in average beak size following the rainy season in 1983 as the birds adapted to the availability of softer seeds.

If you have specific graph options to choose from, I can help you identify which one aligns most closely with this interpretation.