Good-genes effects in sexual selection

The magnitude of the e¡ect of good genes as a viability bene¢t accruing to choosy females remains a controversial theoretical and empirical issue.We collected all available data from the literature to estimate the magnitude of good-genes viability e¡ects, while adjusting for sample size. The average correlation coe¤cient between male traits and o¡spring survival in 22 studies was 0.122, which di¡ered highly signi¢cantly from zero. This implies that male characters chosen by females reveal on average 1.5 % of the variance in viability. The studies demonstrated considerable heterogeneity in e¡ect size; some of this heterogeneity could be accounted for by di¡erences among taxa (birds demonstrating stronger e¡ects), and by di¡erences in the degree of mating skew in the species (high skew re£ecting stronger e¡ects). Although these results suggest that viability-based sexual selection is widespread across taxa, they indicate that the e¡ect is relatively minor. Finally, there was also an e¡ect of publication year in that the more recent studies reported reduced e¡ects. This may re£ect publication biases during paradigm shifts of this debated issue, but it should also be recalled that the studies have only partly estimated the full ¢tness consequences of mate choice for o¡spring