[Pollinator] Tongue Orchids’ Sexual Guile: Utterly Convincing

[Ladadams at aol.com]

Tongue Orchids’ Sexual Guile: Utterly Convincing  
 

 
 
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By _CAROL KAESUK YOON_ 
(http://topics.nytimes.com/top/reference/timestopics/people/y/carol_kaesuk_yoon/index.html?inline=nyt-per) 
Published: July 15, 2008
 
Orchids, gorgeous and elegant, are also some of the most deceitful flowers,  
having evolved sometimes elaborate ruses to lure pollinators.  
 
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TRICKY Tongue orchids of Australia, excellent  mimics of female wasps. 
 
Related
Web Link
_Orchid Sexual Deceit Provokes  Ejaculation_ 
(http://www.journals.uchicago.edu/doi/abs/10.1086/587532)  (The American Naturalist)


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In a new study of the most brazen of these botanical cheats, the species that 
 entice pollinators with false promises of sex, scientists have discovered 
that  one group of orchids has taken the art of manipulation to shameless 
heights. 
Sexually deceptive orchids, as biologists have long known, look and can even  
smell so much like a female insect that males will try to mate with the 
flower  in a sometimes vigorous process that can result in pollination. But 
scientists  now report that the tongue orchids of Australia are such thoroughly 
convincing  mimics of female wasps that males not only try to mate with them, but 
they  actually do mate with them — to the point of ejaculation.  
“It’s always been described as pseudocopulation,” said Anne Gaskett, a  
graduate student at Macquarie University in Australia and the lead author of the  
study. “But it looked like true copulation to me.” 
The discovery that orchids can induce such an extreme response is more than  
just bizarre natural history, because biologists have always assumed that the  
sexual misrepresentations of orchids were harmless to the duped males, no 
more  than a comical exercise in frustration. 
Yet the study, _published last month in The American  Naturalist_ 
(http://www.journals.uchicago.edu/doi/abs/10.1086/587532) , suggests a potentially huge 
cost to the wasps. 
“If males waste all their sperm on orchids,” Ms. Gaskett asked, “what have  
they got to offer a real female?” 
Beyond that, why, scientists asked, would orchids do such an evolutionarily  
foolish thing? Why would a flower evolve to compromise the ability of its  
pollinator to reproduce? 
So many orchids treat their pollinators so nastily, with false promises of  
food and sex or the occasional dunking of insect visitors into bucket-shaped  
petals full of liquid, that naturalists have puzzled over the relationship for  
more than a century.  
Darwin was so consumed by the odd interactions that after “The Origin of  
Species,” his next book was an entire volume on the subject, “The Various  
Contrivances by Which Orchids Are Fertilized by Insects.” 
In the case of the tongue orchids and their dupe wasps, at least, scientists  
say they may have deciphered why these flowers abuse their visitors: the  
treatment of the wasps may, in fact, be very much to the orchids’ advantage. 
In wasps, the sex of an individual, male or female, is determined by a  
peculiar genetic system known as haplodiploidy. In this system, females are  
produced by an egg from their mother and a sperm from their father. But males  have 
just half of the genetic complement and are produced by females from just  an 
egg, without the aid of a male or a single drop of sperm.  
For an orchid that is pollinated just by males, depleting sperm that would be 
 used just to produce females might not be a drawback at all. It could even 
be a  plus, because some female wasps without sufficient sperm tend to produce 
more  sons — or, from the orchid’s perspective, more pollinators.  
Increasing the numbers of males, scientists say, could even make males a bit  
more desperate and less discriminating — another potential advantage for an  
orchid trying to fool a male into giving the not-quite-right-looking fake 
female  sitting immobile inside its petals a  try. 
_More Articles in Science  »_ 
(http://www.nytimes.com/pages/science/index.html) 


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Laurie Davies Adams
Executive Director
Pollinator  Partnership 
423 Washington Street, 5th floor
San Francisco, CA  94111
415-362-1137
LDA at pollinator.org

_www.pollinator.org_ (http://www.pollinator.org/) 

_www.nappc.org_ (http://www.nappc.org/) 

National Pollinator Week is June 22-28, 2008. 
Beecome  involved at _www.pollinator.org_ (http://www.pollinator.org/) 



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