60. What evolutionary mechanism would explain the increased frequency of male birds with narrow, elongated tail feathers within this population?
Answer: B
Sexual selection explains the increased frequency of male birds with narrow, elongated tail feathers.
In this population, sexual selection is the evolutionary mechanism that accounts for the prevalence of male birds exhibiting narrow, elongated tail feathers. These traits likely enhance male attractiveness to potential mates, thereby increasing their reproductive success.
A) Gene flow
Gene flow refers to the transfer of genetic material between populations. While it can influence genetic variation, it does not specifically account for the preference of certain traits within a given population, such as the elongated tail feathers of male birds in this scenario.
B) Sexual selection
Sexual selection is the correct mechanism, as it directly addresses the role of mate choice in the evolution of specific traits. In many bird species, males develop elaborate features to attract females, and the increased frequency of narrow, elongated tail feathers suggests that these traits are favored by female choice, enhancing the reproductive success of those males.
C) Genetic drift
Genetic drift involves random changes in allele frequencies within a population, often having a more pronounced effect in small populations. It does not account for the directional selection of traits based on sexual attractiveness, as seen with the elongated tail feathers in male birds.
D) Artificial selection
Artificial selection is the intentional breeding of organisms by humans for desired traits. This mechanism is not relevant in the context of natural populations of birds where mate choice and natural reproductive success determine the frequency of traits, such as the elongated tails.
Conclusion
Sexual selection is the definitive mechanism explaining the increased prevalence of male birds with narrow, elongated tail feathers, as it relates directly to mate attractiveness and reproductive success. Other options like gene flow, genetic drift, and artificial selection do not adequately describe the scenario, as they lack the focus on mate preferences that drives the evolution of such traits.