Sexual Dimorphism

2 Pages 575 Words

Sexual dimorphism is secondary sexual characteristics, marked differences, which are not directly associated with reproduction. It is a distinction in appearance. The distinction in appearance can range from size or in features that show more colorful feathers, larger manes, or bigger antlers. Males tend to be the ones to attract females with these distinctions, at least in most vertebrates. A male peacock uses its very distinct and colorful plumage to attract the females. Also, larger males are more likely to win over a female when competing with a smaller male of the same species. Darwin referred to sexual dimorphisms as sexual selection. Today, we use the terms intrasexual and intersexual selection. Sexual selection is a form of natural selection but instead favors traits that are more likely to attract females for reproduction. Intrasexual selection is the direct competition of individuals within one sex for mates of the opposite sex. Usually, it’s males competing for females. For example, a male deer will use its antlers as a weapon against other male deer to try to show who is the stronger, more fierce, male, all the better to win over the females. Also, males competing with each other over certain territories that are predominately female would also be considered intrasexual selection because the stronger will beat the weaker for that area and more apt to mate. Then, there is the other selection, intersexual selection. Intersexual selection is when individuals of one sex are choosy in selecting mates from individuals of the opposite sex. This time it’s the females who are being choosy. For example, going back to the male peacock, which uses its color plumage to attract a female. The more outrageous and extravagant its feathers are the better luck he will have attracting a female. Male ducks, mallards, are also the more colorful ones, while the females are mostly dull and brown, better camouflaged from preda...