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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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Keeping Out the Competition
25 June 2003 (All day)
Some female spiders are notorious for devouring their mates during or after sex. Males, as you might expect, don't go gently. Now scientists report that males of one species seem to keel over intentionally. This death wish could be a strategy to plug female genitals with their corpses and block any competitors from mating, a radical and previously untested mating strategy.
In some other spider species with deadly couplings, males vigorously try to escape from cannibalistic females. This makes sense from an evolutionary standpoint: Surviving males could try to keep sowing their genetic oats by mating with other females. But a few spiders, such as male Australian redback spiders, practically somersault into female jaws.
Even given the bizarre antics in other species, evolutionary biologists Matthias Foellmer and Daphne Fairbairn at the University of California, Riverside, were surprised at what they found, during an unrelated study, in the garden-dwelling spider Argiope aurantia. The genitals of male spiders are a pair of extremities called pedipalps, found behind the fangs. In field and lab experiments, the researchers found that while some males attempted escape after inserting just one palp, all males that achieved both insertions died within 15 minutes of mating, even if the females didn't chow down on them. Other males often tried to pull out their dead rivals, but succeeded in only three out of 11 observed cases, the researchers report online 25 June in the Proceedings of the Royal Society: Biology Letters. Foellmer says this suggests that such sacrifices provide an evolutionary advantage, by safeguarding paternity.
There are still many secrets regarding male sacrifice during mating, says behavioral ecologist Jutta Schneider of the University of Bonn in Germany. If the second insertion affects paternity and sperm competition, she says, that would help explain why males are willing to go to such lengths.