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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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Pisces Swingers Bear Better Babies
22 August 2000 7:00 pm
A wandering eye appears to reward female guppies with more talented offspring, according to a new study. Having multiple sexual partners is worth all the trouble--although it's still not clear how the fish manage to improve their reproductive success.
Males have an obvious motive for mating with many females: They spread their genes far and wide by fathering as many young as possible. Although females of many species mate with multiple males, the benefits aren't as obvious: Researchers generally assumed that one male should provide enough sperm to fertilize plenty of eggs. And promiscuity has its drawbacks--all that time spent mating could be better spent feeding or avoiding predators, it seems. To investigate why female guppies still entertain multiple suitors despite the dangers, Jonathan Evans and Anne Magurran of the University of St. Andrews in Scotland played matchmaker with 76 females.
Promiscuity paid off big time. On average, females mated to four different males gave birth to 73% more young and had 20% shorter gestation times than females who mated with only a single male repeatedly, the researchers report in the 22 August issue of the Proceedings of the National Academy of Sciences. In addition, the young from females who had multiple partners were more adept at schooling (swimming in tandem with another fish) and escaping from trouble, critical survival skills for a young fish.
The authors speculate that females who mate with many males have a better shot at finding ones with larger sperm counts--perhaps one male doesn't always provide enough sperm to fertilize all the available eggs after all. They also suggest that the female may control her gestation period; after mating with her first beau, she may delay fertilization in the hope that something better comes along.
The differences in offspring from singly and multiply mated females are "astonishing," says evolutionary and behavioral biologist Anne Houde of Lake Forest College in Illinois. But she cautions that it remains to be seen whether multiple mating has the same benefits in the wild, where other mating behaviors come into play.