12 - males: Horns, large body size, sperm competition,...

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General result is that sex with higher parental investment = limiting resource . Since this sex is usually females, this will lead to male-male competition for access to mates (like resource competition in ecology), and female choice where females choose among males so that they may prudently commit their higher parental investment. Put another way, males will increase fitness by increasing the number of fertilizations they can perform, leads to Intrasexual selection (selection among individuals of the same sex). Females will increase fitness by being choosy , leads to Intersexual selection where the high-investment sex chooses among the low investment sex. As a consequence, these forms of sexual selection can lead to the evolution of traits that better enable each sex to perform its "fitness-increasing" behavior. In
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Unformatted text preview: males: Horns, large body size, sperm competition, mating plugs. In females : choosy behavior . The existence of choice in females can lead to traits in males that tend to give individuals an advantage in attracting mates: Plumes, coloration . These present a problem, however. Have these phenotypic characters evolved so that males can out compete other males to gain access to females, OR, have they evolved so that a male might win and the be in a position to be chosen by females ? The relative contributions of intra and intersexual selection in the evolution of some traits can be difficult to distinguish. Ecological contexts in which parental care might be given can influence the amount of parental care invested in offspring....
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