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For spiders, casual dating dangerous
WASHINGTON (Reuters) -- A study of spiders shows female wolf spiders will eat strange-looking males that try to mate with them, but spare and even hook up with familiar-looking males. The findings provide not just an interesting insight into spider behavior, but may help explain actions by "higher" animals, said arachnologist Eileen Hebets of Cornell University in New York. "The female is using earlier experience that is going to affect her mate choice later," Hebets said in a telephone interview this week. "It is reasonable to expect that is a common thing in other animals." Hebets worked with Schizocosa uetzi spiders, commonly known as wolf spiders. They have an elaborate courtship ritual in which males arch their brown or black forelegs and vibrate their bodies.
The female, which is slightly larger, can choose to mate, to run away or to eat her suitor. Sometimes she eats the hapless male after mating, Hebets said. Hebets painted the legs of male spiders either brown or black with nail polish, and then raised females with either brown- or black-marked males, but not both. When the females became sexually mature, she would put into their boxes a male of either color and watch what happened. The females were not exposed to males they already knew -- just males marked with the same shade of nail polish. "They just look like somebody they might know. None saw the same male ever," Hebets said.
Writing in the Proceedings of the National Academy of Sciences, Hebets said the females were more likely to eat males painted with the "wrong" color instead of mating with him. The more a female had been exposed to males with their legs painted a certain color, the more likely she was to eat a male painted with the other color, Hebets found. "Finding this behavior is really surprising. Social experience influences mate choice," she said. "It opens all kinds of possibilities. It could be this is a way of learning your species and making sure that when you get older, you are mating with the right species." She said it was the first study to look at social recognition in mate choice in an invertebrate. "This shows that invertebrates have social recognition, and it can be maintained and remembered even through the molting process. These influences affect adult behavior and possibly the evolution of traits," she said. Animals share many genes and humans share genes, and perhaps behaviors, with worms, flies and other bugs. The color of a male's legs had no effects on whether a female decided to eat him after mating, Hebets said. But she said it was more unusual for a female wolf spider to eat a male she had just mated with. "The percentage of post-copulatory cannibalisms were certainly nothing out of the ordinary," she said. Despite their reputation, not all species of female spiders eat their mates and suitors. "Some may just see the males as food," Hebets said. "Some incorporate cannibalism into mating. In some, the females are actually eating the male while he is inserting sperm." Copyright 2003 Reuters. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.
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Some may just see the males as food.
