Acoustic signals used by males to attract females are among the most prominent examples of secondary sexual traits, yet we have only limited understanding of their genetic architecture. Male crickets produce a calling song to attract females and then switch to a courtship song that incites...

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...

Previous studies have attempted to assess the reproductive benefits of polyandry in mammals but have failed to account for variation in mating frequency across experimental treatments. Recently, it has been shown that multiply sired litters are common in natural populations of house mice,...

The evolution of male secondary sexual traits traditionally has been ascribed to precopulatory sexual selection. In contrast, the importance of postcopulatory sexual selection for the evolution of secondary sexual traits is uncertain, and what little evidence exists for this process to...

Sexual selection typically operates via male contest competition and female choice, favoring the evolution of secondary sexual traits in males. However, there are numerous taxa in which females possess secondary sexual traits and the selective pressures operating on female ornamentation are not...

The outcome of fights between males can often represent an honest signal of male quality and are therefore widely used by females in mate choice. Indeed, female preference for males that win fights has been demonstrated in numerous animal taxa, and many recent studies have focused attention on...

Studies of fertilization success have demonstrated that male effects are often a strong and important source of variation in P-sub-2 (the proportion of offspring that are fertilized by the second male to mate). More recently there has been emphasis on female processes that occur during and after...

Humans find symmetrical faces more attractive than are asymmetrical faces. Evolutionary psychologists claim that our preference for symmetry can be explained in the context of mate choice because symmetry is an honest indicator of the genetic quality of potential mates. These arguments assume...