Assessment | Biopsychology | Comparative | Cognitive | Developmental | Language | Individual differences | Personality | Philosophy | Social |
Methods | Statistics | Clinical | Educational | Industrial | Professional items | World psychology |

Biological: Behavioural genetics · Evolutionary psychology · Neuroanatomy · Neurochemistry · Neuroendocrinology · Neuroscience · Psychoneuroimmunology · Physiological Psychology · Psychopharmacology (Index, Outline)

In the evolutionary biology of sexual reproduction, the operational sex ratio (OSR) is the ratio of sexually competing male to females that are ready to mate.[1] It is different from the physical sex ratio in that physical sex ratio also takes into account sexually inactive individual organisms, and sexually non-competitive individuals. This concept is especially useful in the study of sexual selection since it is a measure of how intense sexual competition is in a species, and also in the study of the relationship of sexual selection to sexual dimorphism.[2]


  1. Kvarnemo, C., Ahnesjo, I. (1996). The dynamics of operational sex ratios and competition for mates. Trends in Ecology & Evolution 11 (10): 404–408.
  2. Mitani, J.C., Gros-louis, J.; Richards, A.F. (1996). Sexual Dimorphism, the Operational Sex Ratio, and the Intensity of Male Competition in Polygynous Primates. The American Naturalist 147 (6): 966–980.
  • Tim Clutton-Brock, Science, 318, p. 1882, 21 Dec 2007
This page uses Creative Commons Licensed content from Wikipedia (view authors).

Ad blocker interference detected!

Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers

Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected.