The dynamics of operational sex ratios and competition for mates.

In sexually reproducing animals, individuals of one sex may have to compete for access to mating partners of the opposite sex. The operational sex ratio (OSR) is central in predicting the intensity of mating competition and which sex is competing for which. Thanks to recent theoretical and empirical advances, particularly by exploring the concept of OSR, sexual selection studies today are becoming more fine-tuned and dynamic. The original role of parental investment in predicting sexual selection has recently been complemented by the use of sexual differences in potential reproductive rates (PRR).