Sexual Conflict Affects Females More Than Males: Burying Beetles and Parental Care

It turns out that sexual conflict may affect females more than males--at least when it comes to beetles. Scientists have discovered that sexual conflict over mating impacts the parental care behavior and reproductive productivity of burying beetles.

Burying beetles have surprisingly complex parental care. The adult beetles feed their "children" partially digested food after the offspring beg to be fed by touching their parents. While both males and females provide care for their young, though, the females are the primary caregivers.

Intrigued by this beetle behavior, the researchers decided to determine if and how mating behaviors co-evolved with parental care behaviors. Classical parental care theory suggests that males are expected to provide less care when offspring in a brood are less likely to be on their own. Yet previous research has shown that this is not always the case.

The scientists artificially selected burying beetles for either high or low mating rate for seven generations. They then examined patterns of parental care and productivity of different combinations of male-female pairs.

So what did they find? It turns out that male care behavior didn't change in response to selection on mating rate. Females, however, responded to selection for high mating rates with a reduction in parental care.

"Our research shows that, despite selecting on a mating behavior that is known to increase male assurance of paternity, there was no correlated change in male parental care behavior," said Nick Royle, one of the researchers, in a news release. "Instead, costs of mating in females appear to determine how patterns of parental care evolve in response to changes in mating behavior. In species with biparental care, such as burying beetles, most birds and humans, our results indicate that males are followers not leaders in the evolution of family life. It is how selection acts on females, not males, that really counts here."

The findings are actually contrary to classical parental care theory. In contrast, they support the idea that sexual conflict is more important than parentage when it comes to determining patterns of parental care.

The findings are published in the journal Ecology Letters.