August 30, 2009 10:24 AM Subscribe
posted by netbros (15 comments total)
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How do you spread your genes around when you're stuck in one place? By tricking animals, including us, into falling in love. Orchids — Love and LiesOrchids are dizzying in their diversity
. Over the past 80 million years, some 25,000 wild species have taken root on six continents, in nearly every kind of habitat. Representing a full fourth of the world's flowering plants, there are four times as many orchid species as mammals, and twice as many as birds.
Perhaps the most clever deceit of all is offered by those orchids that hold out the promise of sex. And not exactly normal sex. Really weird sex, in fact. I went in search of one of the most ingenious and diabolical of orchids: the Ophrys. (Some botanists call it the "prostitute orchid.") I'd been eager to lay eyes on this orchid and meet its hapless pollinator ever since reading about its reproductive strategy, which involves what my field guide referred to as "sexual deception" and "pseudocopulation."
The pollination strategy of the Ophrys is, like that of so many orchids, ingenious, intricate, wily, and seemingly improbable—so much so that proponents of intelligent design sometimes point to orchids as proof that the hand of a higher intelligence must be at work in nature. (And a rather sadistic intelligence at that.) Yet the peculiarities of orchid sex actually offer one of the great case studies of natural selection, as Charles Darwin himself understood. Darwin was fascinated by orchid pollination strategies, and though he was puzzled by the purpose of Ophrys's uncanny resemblance to bees (pseudocopulation wasn't observed until 1916), he taught us much of what we know about these plants in The Various Contrivances by Which Orchids are Fertilised by Insects, the volume he published immediately after The Origin of Species.
Outcrossing, or mixing one's genes with distant mates, increases vigor and variation in one's offspring, maximizing fitness. The sexual frustration of a deluded bee turns out to be an essential part of the orchid's reproductive strategy. Determined not to make the same mistake again, the bee travels some distance and, if things work out for the orchid, ends up pseudocopulating (and leaving his package of pollen) with an orchid a ways off. That distant orchid is likely to look and smell ever so slightly different from the first, and some botanists believe these subtle variations from plant to plant are part of the orchid's strategy to prevent bees from learning not to fall for a flower. "Imperfect floral mimicry" [pdf] is the botanical term for this adaptation.
There's a video on YouTube, a riveting snippet of interspecies porn, in which you can watch a wasp be utterly bamboozled, and then humiliated, by an Australian tongue orchid. The tongue orchid (Cryptostylis) lures its pollinator by deploying a scent closely resembling the pheromone of the female wasp.
"Prurient apparitions," is how Victorian critic John Ruskin described these flowers. Prurient? Is it possible that humans can look at an orchid and, like the deluded orchid bees or male dupe wasps, see an apparition of female anatomy? (Georgia O'Keeffe certainly did.) Could it be that plant sex and animal sex have gotten their wires crossed in human brains just as they have among the bugs? That accident of evolution has proved another happy one for the orchid, for look how much we humans now do for these flowers: the prices paid, the risks to life and limb endured, the pains taken …