Kinky Female Bats Share Mates With Their Mothers, Avoid Incest

Female greater horseshoe bats share their mates with their mothers and daughters. CREDIT: © Gareth Jones

Female greater horseshoe bats like to keep it all in the family - they share mates with their mothers and even their grandmothers - but, somehow they avoid incest, a new study reports.

"She won't mate with her father. But she will mate with her mother's partner - but only when her mother has switched partners," said study leader Stephen Rossiter of the Queen Mary, University of London of the female bats.

Although this behavior sounds strange - and leads to some very confusing family trees - Rossiter suggests that it evolved to tighten relationships within the colony.

"One possibility is that by increasing kinship, sharing sexual partners strengthens social ties and promotes greater levels of cooperation within the colony," Rossiter said.

In some cases a female and her maternal half-aunt were also half-sisters on their father's side. It's pretty confusing, but think of it like this:

Female 1 mates with male 1, producing female 2. Later on, female 1 ditches male 1 and mates with male 2, producing female 3. Meanwhile, female 2 gets in on the action and also mates with male 2, producing female 3a.

Females 3 and 3a are in related two ways now - female 3 is 3a's half aunt on their maternal side, but they're sisters on their dad's side. And, since horseshoe bats have a life span of about 30 years, it only gets more complicated down the road.

This study was part of one of the world's longest-running wild animal population studies. The researchers used genetic analysis techniques to draw up the family trees for over 450 bats in the attics of Woodchester Mansion in Gloucestershire, UK.

This research is detailed in the Sept. 15 issue of the journal Nature.