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May 22, 2009 03:00 PM | 9
You probably knew that honeybees typically die after they sting you, as their barbed stingers are torn from their abdomens. But did you know that after mating, some male spiders break off the ends of their palps—the organ used to transfer sperm—inside the female?
That’s right. And afterward, this mutilated “eunuch” will stick around the female’s web and prevent her from shacking up with his competitors.
In a paper in this month’s issue of the journal Evolution, Jonathan Coddington of the Smithsonian Institution, along with colleagues Matjaz Kuntner and Jutta Schneider, studied the evolution of the genitals of males and females in 32 species of Nephilid spiders, including the golden orb weaver (pictured). Whereas most studies of sexual selection have focused on how males compete with each other for dominance and how females pick their mates, spider genitalia tell another side of the story: that the battle of the sexes continues during and, even after sex. Males want to ensure that their sperm—and only their sperm—fertilizes the females’ eggs, while females would like to keep their options open.
The result, Coddington says, is that male and female genitalia have grown increasingly complex over evolutionary time. Males gradually developed hooks, ridges, and twists on their palps as female genitalia transformed from a slit with a straight, short duct to a series of elaborate chambers making them more difficult to “plug".
“Sex is one of the more powerful driving forces behind evolution,” Coddington says, “and it just so happens that spiders have some of the most bizarre sex of animals on Earth.”
Image of golden orb weaver courtesy of Jonathan Coddington
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9 Comments
Add Commentsex and male nature for dominancy over female partner is a unique feature in all livin being. a debate is necessary why female accomodate other female for her male in almost all living being while male does not?
Reply | Report Abuse | Link to thisInteresting question.
Reply | Report Abuse | Link to thisWouldn't that depend to some extent on whether the species was an r or a k strategist? If the parents both take care of the offspring, it makes less sense to spread sperm far and wide, because the male can't help raise the young. But if the young are on their own from the start, then it probably doesn't matter to the female whether or not the male limits his genetic contribution to her offspring, unless the offspring will be in a limited geographic region and compete with each other. In lions, the females hunt together, so a "harem" might make evolutionary sense for them, anyway.
Reply to "Barbillbullshit":
Reply | Report Abuse | Link to thisThere's no need for any debates before anyone has ever established the reality of your groundless rule about what you believe to be "a unique feature in all living being".
In case of spiders, the male guards the female after copulation against any other intruding male because it wants to ensure that its own sperms should fertilize eggs released by the female. This sounds normal, not bizarre, irrespective of whether male genitalia broke down or not.
Reply | Report Abuse | Link to thisIn case of spiders, the male guards the female after copulation against any other intruding male because it wants to ensure that its own sperms should fertilize eggs released by the female. This sounds normal, not bizarre, irrespective of whether male genitalia broke down or not.
Reply | Report Abuse | Link to thisWhile I understand the female spider's preferring to 'keep her options open' viz sexual partners, I'm not sure I understand the evolutionary force that leads to this reproductive arms race of ever-more-complex genitalia.
Reply | Report Abuse | Link to thisWhat significant adaptive advantage is conferred on the female spider by being able to mate with more male spiders? Either way she gets offspring, which, it seems to me, are no more or less likely to be successful than offspring that may have come from a later mating. How does the spider with the more complex vagina come to have more successful offspring?
And is there a song lyric in here?
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