Question

Read the passage and answer the following questions:

A population of birds (population A) on a remote, isolated island is studied to determine beak length. The resulting data are plotted in Figure 1.

Figure 1

Suppose that 200 years later, the beaks of the birds on the island were again measured (Population B). The data, when plotted, yielded a graph as in Figure 2.

Figure 2

What is the most likely reason for the difference in distribution of beak lengths between the data plotted in Figure 1 and the data plotted in Figure 2?

• A. All birds with beaks of 30 mm flew to a new island over the 200-year time span.
• B. Birds with beaks of 30 mm were selected against.
• C. Predators consumed birds with beaks of 40 mm.
• D. Predators consumed birds with beaks of 20 mm.
• E. Birds with beaks of 30 mm were selected for extinction.

Answer 1

The correct option is B Birds with beaks of 30 mm were selected against.

The graph shows that birds with beak length 30 mm were not favored by natural selection. Since the island was remote, there is no expected nearby island where birds can go.

Figure 2 shows high number of birds with 20 mm and 40 mm beak size. If birds with beak size 30 mm were extinct, the graph would not have shown two different population in figure 2.

Therefore, the correct answer is option B.