Multiple mates increase reproductive success for female prairie dogs

Washington: A new study has suggested that mating with more than one male increases reproductive success for female prairie dogs, despite an increase in risks.

Mating entails significant costs such as increased susceptibility to predation and increased exposure to diseases and parasites. So why would a female prairie dog take the risk to mate with multiple males? The answer is simple and clear: female prairie dogs that mate with two or more males rear more offspring than those that mate with only one. "Prairie dogs are excellent models for a study of polyandry because they are easy to livetrap, mark, and observe. Further, each female is sexually receptive for only 5-6 hours of a single day each year, so my students and I can record all the males with whom she mates during that small window of opportunity," behavioral ecologist John Hoogland , Professor at the University of Maryland Center for Environmental Science`s Appalachian Laboratory. "Finally, females remain in the same territory after mating, so we can determine reproductive success for all the females in our study-colony each year." Hoogland quantified female reproductive success by tracking the number of offspring that survived until the following spring. Other components of fitness were also considered, but Hoogland concluded that the number of yearlings was the best estimate of a female`s ultimate reproductive success. Hoogland and his research assistants were able to document 2,504 copulations by 1,426 females living under natural conditions from 1978 through 2012. They found that the frequency of polyandry (mating with more than one male) varied significantly among the four species. The black-tailed and white-tailed prairie dogs were mostly monandrous (mating with only one male), but the Gunnison`s and Utah prairie dogs were mostly polyandrous. The number of yearlings was higher for polyandrous females for three of the four species. For Gunnison`s and white-tailed prairie dogs, however, polyandrous females were less likely than monandrous females to survive until the next mating season. The study was published in the Journal of Mammalogy.