Question 60

Sexual selection explains the increased frequency of male birds with narrow, elongated tail feathers.

The phenomenon of male birds exhibiting narrow, elongated tail feathers is primarily attributed to sexual selection, where traits that are attractive to potential mates become more prevalent over generations.

A) Gene flow

Gene flow refers to the transfer of genetic material between populations. In this context, it does not explain the specific increase in narrow, elongated tail feathers since this mechanism would involve the introduction of new genetic variations rather than the enhancement of existing traits within a population.

B) Sexual selection

Sexual selection is the correct explanation for the increased frequency of narrow, elongated tail feathers in male birds. This mechanism occurs when certain traits enhance an individual's chances of attracting mates, leading to a higher reproductive success for those individuals with the preferred traits, such as longer tails.

C) Genetic drift

Genetic drift involves random changes in allele frequencies, particularly in small populations. While it can lead to changes in trait frequencies, it does not specifically favor traits that enhance mating success, unlike sexual selection, which directly impacts reproductive outcomes based on mate preferences.

D) Artificial selection

Artificial selection is the process by which humans breed specific traits in organisms. This mechanism does not apply to the natural phenomenon of male birds developing elongated tail feathers, which occurs without human intervention and is driven by natural mate selection processes.

Conclusion

Sexual selection is the definitive mechanism responsible for the increased prevalence of narrow, elongated tail feathers among male birds, as it directly relates to mating preferences. In contrast, gene flow, genetic drift, and artificial selection do not suitably explain this specific evolutionary trend within the population.