University of Guelph researchers have finally figured out why female squirrels are so darn promiscuous. Turns out it has nothing to do with genes and everything to do with how many males are knocking at their door.
"Their behaviour is overwhelmingly influenced by opportunity," said graduate student Eryn McFarlane, who, along with integrative biology professor Andrew McAdam and a team of researchers from across Canada, solved a mystery that has baffled biologists for years.
Their findings appear in the Royal Society Journal Biology Letters.
Female squirrels are less than picky when it comes to mating, often entertaining as many suitors as possible. Such risky female behaviour is puzzling in the mammal world.
Although it makes sense for male squirrels to have as many mates as possible to ensure the most offspring, promiscuity doesn't always make sense for females, said McFarlane.
"Having multiple partners means more energy expended on mating, increased exposure to predators as well as increased potential for the spread of sexually transmitted diseases," she said. "Promiscuity also encourages harassment from male squirrels trying to coerce them into having sex."
Trying to solve this puzzle has prompted a lot of research into the possible benefits of mating with many males, said McAdam. However, optimal mating strategies can evolve only if there is a genetic basis to the behaviour.
The Guelph team discovered that female squirrel behaviour results from opportunity alone and not from genetics, limiting its ability to evolve.
"We found the more males in the area interested in participating in the mating chase, the more squirrels she will mate with," McFarlane said. "There are no strong ties between mating behaviour and genetics in red squirrels. So even if the costs of mating with many males outweighs the benefits there doesn't seem to be much capacity for them to evolve lower levels
|Contact: Deidre Healey|
University of Guelph