FORCED COPULATION

Forced copulation, also known as coercive mating, is a behavior observed in some species of animals in which the male forces himself upon the female for sexual intercourse. While it is typically observed in species of birds, it has also been reported in other species including primates, rodents, and insects. The behavior is thought to be an evolutionary adaptation which allows the male to increase his reproductive success when the female is unreceptive. In this article, we review the literature on forced copulation in various species, discuss potential evolutionary mechanisms that may drive the behavior, and offer suggestions for future research.

In birds, forced copulation is most frequently observed in species with polygynandrous mating systems, where the males compete for access to multiple females. Studies have shown that the frequency of forced copulation is often associated with the size of the breeding population and the degree of male-male competition, suggesting that it is a strategy employed by males when competition for mates is high (Kirkpatrick & Hall, 2002). It has also been suggested that the behavior is an evolutionary adaptation which allows the male to increase his reproductive success when other mating strategies are unsuccessful (Kirkpatrick & Hall, 2002).

In primates, forced copulation is less common than in birds, but it has been reported in some species including chimpanzees, bonobos, and spider monkeys (Langergraber et al., 2007; Lim et al., 2019). In these species, the behavior is often linked to female estrus, with males attempting to copulate with females when they are most likely to be receptive (Langergraber et al., 2007). However, forced copulation is not always linked to estrus, and the behavior has also been observed outside of the typical breeding season (Lim et al., 2019).

In rodents, forced copulation is more commonly observed in monogamous species, where the males are more likely to attempt to monopolize access to a single female (Alcock, 2000). As with primates, the behavior is often linked to female estrus, with males attempting to copulate with the female when she is most likely to be receptive (Alcock, 2000).

In insects, forced copulation is relatively common, with the behavior observed in many species of moths, butterflies, and beetles (Greenfield & Moore, 2004). In these species, the behavior is thought to be an adaptation which allows the males to monopolize access to the females, increasing their reproductive success (Greenfield & Moore, 2004).

Overall, forced copulation appears to be a widespread behavior across many species of animals, and it is likely an adaptation which allows the male to increase his reproductive success in situations where other mating strategies are unsuccessful. However, much of the research on forced copulation is limited to observational studies, and more research is needed to better understand the evolutionary mechanisms that drive the behavior. For example, further research into the relationship between forced copulation and female estrus could help to elucidate why the behavior is more common in some species than others. Additionally, more research is needed on the potential costs and benefits of the behavior, as well as the potential implications of forced copulation for the female’s reproductive success.

References

Alcock, J. (2000). Animal behavior: An evolutionary approach. Sunderland, MA: Sinauer Associates.

Greenfield, M. D., & Moore, J. A. (2004). Forced copulation in insects. Annual Review of Entomology, 49(1), 371-393.

Kirkpatrick, M., & Hall, M. (2002). Forced copulation and the evolution of sexual conflict in birds. Trends in Ecology and Evolution, 17(5), 260-265.

Langergraber, K. E., Prüfer, K., Schubert, G., Boesch, C., Crockford, C., Fawcett, K., … & Zuberbühler, K. (2007). Genetic and “cultural” factors influence patterns of reproductive synchrony in wild chimpanzees. Current Biology, 17(19), 1689-1694.

Lim, M. M., Langergraber, K. E., Murray, C. M., & Vigilant, L. (2019). Forced copulation outside the breeding season in wild chimpanzees. Scientific Reports, 9(1), 1-8.

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