Operational sex ratio, reproductive costs, and the potential for intrasexual competition

The influence of operational sex ratio on the intensity of competition for mates.

The evolution and maintenance of secondary sexual characteristics and behavior are heavily influenced by the variance in mating success among individuals in a population. The operational sex ratio (OSR) is often used as a predictor of the intensity of competition for mates, as it describes the relative number of males and females who are ready to mate. We investigate changes in aggression, cour...

Intrasexual competition enhances reproductive isolation between locally adapted populations

During adaptation to different habitat types, both morphological and behavioral traits can undergo divergent selection. Males often fight for status in dominance hierarchies and rank positions predict reproductive success. Ecotypes with reduced fighting abilities should have low reproductive success when migrating into habitats that harbor ecotypes with superior fighting abilities. Livebearing ...

Local male competition and the sex ratio.

Hamilton (1967) pointed out that Fisher’s (1930) argument predicting an equality of the sex ratio may break down when there is local competition for mates. He considered in particular a model in which the environment consists of a number of isolated patches, each of which is colonized by a number of inseminated females; the offspring breed within the patch before dispersal. The present paper pr...

Risk-taking, intrasexual competition, and homicide.

Gender, Intrasexual Competition, and Online Learning

It has been well established that women are more likely to complete online courses than men (e.g., Young, Dewstow, & McSporran, 1999). The existing literature attempts to elucidate the reasons for this gender difference. Often, the provided explanations are based on the idea that such courses allow for flexibility in time management which permits students to better balance work and family life ...