Sunday, September 9, 2007

Polyandry - a bubbe-maise


Despite mating being a risky business for females – not least with the threat of injury, sexually transmitted diseases and vulnerability to predators - polyandry (females taking multiple mates) is widespread in the animal kingdom.
Dr Stephen Cornell (Leeds) and Dr Tom Tregenza (Exeter) have shown that polyandry may have evolved as a survival technique because it provides genetic benefits for species that either accidentally inbreed, or may have no other choice in certain circumstances.
The researchers used a mathematical model to calculate the genetic advantages of polyandry for species where inbreeding is routine – which is thought to be a very large number of species and includes social spiders and many pests of stored food such as beetles. They found that the genetic rewards are likely to be strong enough to compensate for the risks involved in taking extra mates.
“Not only is mating dangerous enough for females, but most species covered by our model should be able to get all the sperm they need for a lifetime’s reproduction from a single mating, so it has puzzled scientists as to why this type of behaviour would be so common,” says Dr Cornell. “You would think that their time would be better spent foraging for food, or at least avoiding being eaten by predators.”
(more from ScienceDaily)

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