In mammalian males, sexual selection tends to have a greater impact on behavior and morphology than does other forms of natural selection.Due to the combination of females investing more in the care of the offspring and the one-to-one population sex ratio, males are usually the ones in competition for females. Male reproductive success also varies much more than that of the female. It mainly depends on their access to sexually receptive females. It is this rivalry that requires males to develop traits that make them more attractive to females through intersexual selection. Through intrasexual selection, traits are also developed which enhance their success in male-male competition. Intersexual selection can explain the awkward traits such as the peacock’s tail and the frog’s loud croak, while intrasexual selection can explain traits such as the red deer’s antlers. Those favored by intersexual selection are all traits that in one way or another make the male more attractive to the females, therefore increasing their reproductive success. These outcomes would not usually be favored by natural selection since they are most likely to reduce the ability of the animal to survive or acquire resources. Nonetheless, they still evolve since Sexual Selection is often much stronger than normal Natural Selection (Boyd and Silk 2000, p. 216). Traits favored by intrasexual selection may or may not be favored by Natural Selection. The red deer use their antlers when they fight with other males, but can also be used in defense against predators.Intersexual selection, in which the females are the ones that chose their mate, has an evolutionary effect. As females become pickier in their choice of mates according to their features and/or qualities, both their genes for focus on detail and the attractive, yet sometimes exaggerated, genes of the males that they choose are passed on to the offspring. These offspring are then pick...
