Sexual Selection
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[edit] Definition
Sexual selection is an evolutionary selection mechanism in sexual organisms which selects traits related to sexual attraction and mating. In the context of natural selection, access to a sexual partner may be seen as a scarce resource, which individuals compete for.
[edit] Types of Sexual Selection
Primary Sexual Selection is a selection mechanism for traits that directly facilitate the reproductive act. Examples in mammals include anatomical characteristics certainly, but also devotion to child-rearing, and aggression between males who may be sexual rivals.
Secondary Sexual Selection refers to the accidental selection of traits through societal mechanisms or courtship rituals. For example, a person with blond hair is more likely to reproduce with a person who finds blond hair attractive, thus propagating both blond hair and the preference for it.
[edit] Sexually Selected Traits
Strangely, sexual selection can propagate traits that might be unrelated to individual survival. Larger genitalia, for example, does not aid in finding food or fleeing enemies. These traits are selected by virtue of their role in the reproductive process only.
Secondary sexual selection may produce traits that don’t even relate to the survival of the species. For example, blond hair does not really confer any advantage on individuals, nor facilitate reproduction.
[edit] Propagation of non-Survival Traits
There is some debate over whether sexual selection can propagate anti-survival traits to the extent that the survival of the species is threatened. It has been suggested that the enormous unwieldy antlers of the Irish Elk were responsible for its eventual extinction. Many biologists are question whether this was indeed a detrimental trait, or whether the trait was the result of sexual selection.
However, sexual selection is generally accepted as the mechanism by which male birds acquired seemingly anti-survival traits: excessive plumage, wasting time and energy singing rather than foraging, etc.
