Final answer:
Sexual selection promotes speciation by emphasizing traits that enhance mating success and can cause divergent evolution when different traits are favored, potentially leading to reproductive isolation and new species formation.
Step-by-step explanation:
Sexual selection is a driving force in speciation because it amplifies reproductive traits that increase mating success, even if such traits may reduce survival. In instances of sexual dimorphism, males may develop elaborate ornaments or engage in competitive behaviors, creating different selective pressures for each sex. These pressures can lead to the divergent evolution of populations and eventually to the formation of new species as members of the same species start preferring different traits in mates.
For example, the colorful plumage of male birds and the mating dances they perform are often a result of sexual selection. This type of selection can lead to divergence when different traits are favored by females in different environments or populations, eventually causing reproductive isolation and speciation.