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5 December 2013 11:26 am ,
Vol. 342 ,
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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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.