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August 8th, 2008

FIGJAM [Aug. 8th, 2008|06:28 pm]
WTF_Nature

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[drhoz]
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Figs are a highly successful family of plants found all over the world's tropical zone, and well into the subtropical areas as well. They've been around for at least 60 Million years, possibly 80 million, and much of their success comes from a hundred million generations of incest, fraticide, and paranoia. One reason it's hard to be sure when figs first evolved is because they don't spread their pollen around with great abandon - indeed, when your flowers are inside the fruit it would seem difficult to spread your pollen anywhere.

Enter the fig-wasp - enter via the little hole at the end of a fig. There's thousands of species, for the time being bundled together as Agaonids, and each species of fig has at least one fig wasp to go with it.

They aren't very big - about the size of this semi-colon ; but then the hole isn't very big either, and the little fig-wasp lady will probably loose her antennae and wings forcing her way in. Many of them have backwards-pointing teeth on their distinctive, specially tapered, reinforced heads to make it a bit easier, both for them and for the paleontologists picking them out from rocks and amber ( fossils of some genera, still around today, turn up in amber 35 million years old - genetic clocks suggest they might be twice that old ).



Inside the fig, she finds herself surrounded by male flowers, long-stalked female flowers, and short-stalked female flowers, and has a good climb around laying her eggs in the all the ovules she can reach. Then she dies, remaining as a pleasant surprise for her babies when they eventually emerge as adults. Of course, the next generation are going to have other things on their mind - in the case of the males, it's hunting down all their brothers and cut them to pieces. This part of the life cycle is quite difficult to study - leave cutting the fig open a few minutes too late and all you'll find is a stack of dismembered losers and the winner waving his over-sized jaws and cackling "Mine! They're all mine!!! BWAHAHAHA!!!!!!" surrounded by his nubile sisters.

Once he's got them all pregnant he chews his way out of the fig, and his sisters all fly off, covered in fig pollen or carrying it in little pockets. He, born wingless, stays behind to die of a broken heart.

And only then does the fig ripen, ready, finally, to be a juicy corpse-filled snack for some lucky bird, lizard, or primate.

( Just in case you were about to throw up your breakfast, the domesticated figs - possibly the first plants domesticated by humans - are sterile mutants, so the poor little fig wasps are not required. )

The wasps avoid ending up bango-playing yokels because male hymenoptera are usually haploid - they hatch from unfertilised eggs and only have one copy of each chromosome. Thus any genetic problems are obvious, and the bearer swiftly eliminated from the gene-pool. Not all species are so picky about keeping it in the family, though. They'll happily share a fig with a bunch of other clutches - but even these ones can't be too complacent because there's up to thirty other wasps that parasitise the fig wasps, or just parasitise the fig without any benefit to the plant, or parasitise the other parasites - either climbing in after the fig wasp mother, or drilling into the fig from outside with their ovipositors.

And some figs cheat - having seperate male and female fig trees - and the fig wasps emerging from a male fig can't reach the ovules of a female fig and thus die after fertilising all her flowers during the futile search.

I recommend Figweb for all your fig wasp needs - great site.

So it all gets very complicated - a fig lined inside with long and short flowers, and a suite of wasps competing for room inside the fig or inside each other, and an arms race for the biggest jaws, sneakiest fig anatomy, or longest vagina-slash-drillbit that's still light enough to drag around behind you.
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