Sperm competition and cryptic female choice are likely to exert strong postcopulatory sexual selection and may amplify or ameliorate selection acting via male mating success. However, relatively few studies have estimated the potential strength of postcopulatory sexual selection acting within...

Sperm competition theory predicts that among populations and species, male expenditure on the ejaculate should increase with the strength of selection from sperm competition, a prediction for which there is strong evidence from comparative studies of a variety of taxa. Patterns of geographic...

Investment in immunity is costly, so that resource-based trade-offs between immunity and sexually selected ornaments might be expected. The amount of resources that an individual can invest in each trait will be limited by the total resources available to them. It would therefore be informative...