Bird Beak Traits

Question

Scientists collected data about one bird population for five generations. The scientists determined the percentages of birds in the population that had specific beak shape traits, 1-6. The data are represented by the graph shown below.

The line graph titled 'Percentages of Beak Shape Traits in a Population' shows Generation from 0 to 5, in increments of 1, on the horizontal axis. The percentage of population with trait is shown on the vertical axis from 0 to 70, in increments of 10. A solid line labeled 'Beak shape Trait 1' starts at about 15%, gradually falls to 10% in generation 1, slightly rises then falls to below 10% in generation 3, then remains steady through generation 5. A solid line labeled 'Beak Shape Trait 2' starts at about 15%, gradually falls to 10% in generation 2, remains steady at 10% in generation 3, and falls to 0% in Generation 5. A solid line labeled 'Beak Shape Trait 3' starts just below 20%, falls to 10% in Generation 2, rises sharply to about 15% in Generation 3, then falls to slightly above 0% in Generation 5. The dashed line labeled 'Beak Shape Trait 4' starts at 20%, falls to below 10% in Generation 3, and continues to gradually fall to about 5% in Generation 5. Two dashed lines labeled 'Beak Shape Trait 5' and 'Beak Shape Trait 6' start slightly above 20%, rise to above 30% in Generation 1, then gradually rise to about 40% in Generation 3. At generation 3, the beak shape traits diverge. Beak shape trait 5 remains steady at about 40% in Generation 4, then falls to about 35% in Generation 5. Beak Shape Trait 6 sharply rises to 70% in Generation 5.

Multiple Choice Question
The birds in the studied population use their beaks to gather nectar from deep inside flowers. The scientists observed that during the five generations of the bird population, these flowers changed. The average depth of the section of the flower that holds the nectar increased during this time.

Using this information and the data from the graph, which group of birds is most likely to have the longest beaks? Identify this group and the graph that best reflects the change in average beak length over time for the total bird population.

A.
The group of birds with Trait 6 are most likely to have the longest beaks.

The graph titled 'Average Beak Length of the Population Over Time' shows Gen 0 to Gen 6, in increments of 1, on the horizontal axis and the average beak length on the vertical axis. The line starts about one-third of the way up the vertical axis and ascends to the top right.

B.
The group of birds with Trait 6 are most likely to have the longest beaks.

The graph titled 'Average Beak Length of the Population Over Time' shows Gen 0 to Gen 6, in increments of 1, on the horizontal axis and the average beak length on the vertical axis. The line starts at the top of the vertical axis and descends to the bottom right.

C.
The group of birds with Trait 3 are most likely to have the longest beaks.

The graph titled 'Average Beak Length of the Population Over Time' shows Gen 0 to Gen 6, in increments of 1, on the horizontal axis and the average beak length on the vertical axis. The line starts at the top of the vertical axis and descends to the bottom right.

D.
The group of birds with Trait 3 are most likely to have the longest beaks.

The graph titled 'Average Beak Length of the Population Over Time' shows Gen 0 to Gen 6, in increments of 1, on the horizontal axis and the average beak length on the vertical axis. The line starts about one-third of the way up the vertical axis and ascends to the top right.

Answer 1

Based on the information provided, the most supported choice is:

A. The group of birds with Trait 6 are most likely to have the longest beaks.

The reasoning behind this choice is as follows:

1. Beak Adaptation: The birds in the studied population use their beaks to gather nectar from flowers, and as the depth of the nectar-holding section of the flowers increased, it would favor birds with longer beaks. Therefore, it is logical to conclude that the birds with the most successful trait in this context would have to adapt to this change.

2. Graph Interpretation: According to the graph description, Beak Shape Trait 6 sharply rises to 70% in Generation 5. This significant increase indicates that Trait 6 becomes the most prevalent in the population, suggesting that this trait is favored by natural selection, likely due to its effectiveness in accessing the deeper nectar.

3. Beak Length Graph: In option A, the graph titled "Average Beak Length of the Population Over Time" shows an ascending line. This aligns with the idea that as Trait 6 becomes more common in the population due to the adaptation to longer nectar depth, the average beak length would also increase over time.

Therefore, based on the scenario presented, option A accurately reflects both the trait of the birds most likely to have longer beaks and the corresponding changes in average beak length over time.