Towards a resolution of the lek paradox

Genetic benefits in the shape of ‘good genes’ have been invoked to explain costly female choice in the absence of direct fitness benefits1,2,3. Little genetic variance in fitness traits is expected, however, because directional selection tends to drive beneficial alleles to fixation4,5,6. There seems to be little potential, therefore, for female choice to result in genetic benefits, giving rise to the ‘lek paradox’7,8,9. Nevertheless, evidence shows that genetic variance persists despite directional selection10,11 and genetic benefits of female choice are frequently reported12,13. A theoretical solution to the lek paradox has been proposed on the basis of two assumptions14: that traits are condition-dependent, and that condition shows high genetic variance. The observed genetic variability in sexual traits will be accounted for, because a proportion of the genetic variance in condition will be captured and expressed in the trait14. Here we report results from experiments showing that male courtship rate in the dung beetle Onthophagus taurus is a condition-dependent trait that is preferred by females. More importantly, male condition has high genetic variance and is genetically correlated with courtship rate. Our results thereby represent a significant step towards a resolution of the lek paradox.