Question

question 1-13
a population of birds living on an island has short, rounded wings that are good for maneuvering through dense trees. one year, a group of birds of the same species migrates to the island. these birds have long, narrow wings that are best for gliding over time. some island offspring are observed with medium - length wings.
which of the following best explains how gene flow contributed to the change in wing shape in the island bird population?
a. alleles from the new birds mixed with the island population, creating new trait combinations.
b. medium - length wings randomly appeared in the population through genetic drift.
c. the arrival of new birds caused mutations in the island birds’ dna.
d. the island birds copied the wing shape of the new birds through learned behavior.

Explanation:

The problem is about the change in wing shape of a bird population due to the migration of new birds with different wing traits. The key concept here is gene flow (migration) introducing new genetic material (traits) and creating new trait combinations through mating. Let's analyze each option:

• Option 1: When new birds (with long, narrow wings) migrate to the island and mate with the existing population (with short, rounded wings), their genes mix, leading to new trait combinations (like medium - length wings). This is consistent with the process of gene flow and sexual reproduction creating new genotypes/phenotypes.
• Option 2: Genetic drift is a random change in allele frequencies, usually in small populations, and it doesn't involve the introduction of new genes from outside populations. So this is not the case here as new birds migrated in.
• Option 3: The air itself doesn't cause mutations in the DNA. Mutations are random changes in the DNA sequence, not caused by the environment in this direct way related to wing shape change due to migration.
• Option 4: Wing shape is a genetic trait, not a learned behavior. Birds can't learn to change their wing shape; it's determined by their genetics.

Answer:

A. Alleles from the new birds mixed with the island population, creating new trait combinations.