Female Mice Mate with Multiple Partners Even in the Absence of Sexual Coercion

Female mice mate with more than one male even in the absence of sexual coercion, a new study published in the Journal of Behavioral Ecology and Sociobiology found.

In many species, females are known to mate with more than one male. In order to figure out why, researchers at the University of Veterinary Medicine in Vienna conducted a series of experiments in which female mice could mate freely with one or two males without the danger of sexual coercion.

In doing so, the researchers found that when the males had mated previously, the females were less promiscuous. This is interesting, the researchers note, because virgin males are more likely to kill a female's offspring. Thus, by showing a greater willingness to mate more frequently when placed in proximity with males that had never mated before, the study provides evidence that female promiscuity is largely a function of infanticide avoidance.

What is not clear is how the females are able to tell whether a male is a virgin or not, though the scientists believe it likely has to do with differences in the males' scent markings.

The scientists also discovered that females were more likely to mate with multiple males when those males produced similar levels of scent markings, suggesting that another factor influencing females' mating behavior has to do with perceived differences in the quality of the males.

"Our results shed some new light on questions about the sexual behaviour of mice, but we still don't have all the answers," lead author Kerstin Thonhauser said in a statement.

Among those questions that still need answering, Thonhauser said, are why intense competition between males yields larger litters and how multiple paternity affects the offspring's fitness.