Until recently, analyses of gender-dependent differences in viability selection and the ontogeny of sexual size dimorphism have been plagued by difficulties in determining the sex of nestling birds on the basis of morphology. Recently, this problem was overcome using molecular sex identification to report for the first time body-size-mediated antagonistic selection on the viability of male and ...

Anisogamy is known to generate an important cost for sexual reproduction (the famous "twofold cost of sex"). However, male-female differences may have other consequences on the evolution of sex, due to the fact that selective pressures may differ among the sexes. On the one hand, intralocus sexual conflict should favor asexual females, which can fix female-beneficial, male-detrimental alleles. ...

Should attractive fathers have more sons? According to widespread verbal arguments, the answer is in the affirmative, but formal models are lacking. We investigate the question by means of an ESS analysis of sexual selection and sex ratio selection. The purpose of this paper is twofold: firstly, we show how an ESS approach can be used to model the coevolution of female mate choice and male seco...