Some beetles use same-sex sexual behavior as a means to establish dominance over male peers. Photo by Matthew Silk/Exeter University
EXETER, England, March 3 (UPI) -- The males of many animal species fight to establish a sexual pecking order. But some beetle species forego violence in favor of sexual affection.
While observing broad-horned flour beetles, Gnatocerus cornutus, in the lab, researchers at the University of Exeter noticed same-sex sexual behavior, or SSB, was being used to establish a reproductive pecking order among males.
As opposed to fighting, many beetles were seen mounting and being mounted by their male peers. Mounters used the SSB as a way to establish dominance over the mounted.
Those who did the most mounting tended to be the most prolific maters, while those who were mounted were less likely to court females and had a lower rate of reproductive success.
Beetles that did not participate in same-sex sexual behavior showed a greater propensity for aggression, suggesting the establishment of a reproductive pecking order serves to not only establish social order but also ensure more peaceful relations among males.
Researchers published their findings in the journal Animal Behavior.
While SSB is common in the animal kingdom, little research has addressed its role in establishing deferential relationships or curbing aggression.
"We therefore tested whether SSB was indeed an extension of male-male competition by observing the relationship between the occurrence of same-sex courtship and acts of aggression, noting whether the beetles switched SSB roles or not," lead study author Sarah Lane, a PhD research student at Exerter, said in a press release. "From this, we could determine whether same sex-sexual encounters influenced aggression amongst competing males."
Just like fighting, same-sex encounters determined fixed differential relationships -- with beetles establishing themselves as either dominant or submissive.
"Our findings provide the first empirical support for the hypothesis that same-sex sexual behaviour is an extension of male-male competition," Lane said. "They also suggest that SSB may act as a non-injurious display, allowing males to resolve dominance hierarchies without escalating into an injurious fight."