Exam 4: The Forces of Evolution and the Formation of Species

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Sexual selection is a type of natural selection that occurs when individuals within a species compete for mates or when females choose mates based on certain traits. This can lead to the evolution of traits that increase an individual's chances of mating, even if those traits may be detrimental to survival.

Reproductive variance refers to the differences in reproductive success among individuals within a species. In many species, males typically have higher reproductive variance than females, meaning that a small number of males father a large proportion of the offspring. Sexual dimorphism refers to the differences in physical characteristics between males and females of a species.

In the case of male peacock feathers, sexual selection has led to the evolution of their elaborate and colorful plumage. Female peahens are more likely to choose mates with vibrant and symmetrical feathers, as these traits are indicative of good health and genetic fitness. This preference has led to the evolution of the peacock's extravagant tail feathers, as males with more elaborate and attractive displays are more likely to successfully mate.

The peculiar morphology of male peacock feathers, therefore, is a result of sexual selection favoring traits that increase mating success, despite the potential costs of maintaining such extravagant plumage. This is a classic example of how sexual selection can drive the evolution of exaggerated and seemingly impractical traits in certain species.