Sexual selection may have played a role in the diversification of skin color and pattern in poison frogs. With female preferences in play, male coloration could evolve rapidly. Sexual selection is influenced by many things. The parental investment may shed some light on the evolution of coloration in relation to female choice. In "Oophaga pumilio", the female provides care for the offspring for several weeks whereas the males provides care for a few days, implying a strong female preference. Sexual selection increases phenotypic variation drastically. In populations of "O. pumilio" that participated in sexual selection, the phenotypic polymorphism was evident. The lack of sexual dimorphism in some dendrobatid populations however suggests that sexual selection is not a valid explanation.