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No one knows exactly when the clones first appeared, but humans only became aware of them in the early 2000s.
It was a German aquarium owner who first brought it to scientists’ attention. In 1995, he had acquired a bag of “Texas crayfish” from an American pet trader, only to find his tank inexplicably filling up with the creatures. They were all, it turns out, clones. Sometime, somewhere, the biological rule that making baby crayfish required a mama crayfish and papa crayfish was no longer inviolate. The eggs of the hobbyist’s all-female crayfish did not need to be fertilized. They simply grew into copies of their “mother”—in a process known as parthenogenesis.
Crayfish specialists were astonished. No one had seen anything like it. But the proof was before their eyes and in 2003, scientists dubbed the creatures marbled crayfish, or Marmorkreb in German.
A new study has found that marbled crayfish are multiplying rapidly and invading ecosystems across the world.
Procambarus virginalis did not exist three decades ago.
Born to a male and female slough crayfish, a species originally from Florida, the original marbled crayfish had an additional set of chromosomes - a mutation that made her distinct from her parents and allowed her to reproduce without having to mate.
Now officially a separate species, the marbled crayfish can been found in the wild in Japan, Madagascar, multiple European countries and the US.
"If you have one animal, essentially, three months later, you will have 200 or 300," Dr Wolfgang Stein, one of the researchers, told Canadian public broadcaster CBC.
There are insect species and lizard species that reproduce by parthenogenesis, so I'm not completely surprised that crayfish can manage this trick. The advantages are obvious. I wonder if anyone has compared the new species' DNA to the original parent species and nailed down what mutations occurred to allow the new mode of reproduction. I also wonder if the marbled crayfish can still reproduce sexually with a male slough crayfish to produce viable young.
There are insect species and lizard species that reproduce by parthenogenesis, so I'm not completely surprised that crayfish can manage this trick. The advantages are obvious. I wonder if anyone has compared the new species' DNA to the original parent species and nailed down what mutations occurred to allow the new mode of reproduction. I also wonder if the marbled crayfish can still reproduce sexually with a male slough crayfish to produce viable young.
it is amazing to see a non-parthenogenic species basically change before our eyes to a parthenogenic one, though. that has never, ever happened before. the parthenogenic one is now formally accepted as a new and distinct species. they sequenced the genome and found that it is now triploid rather than diploid.
they sequenced the genome and found that it is now triploid rather than diploid.
That's interesting, as that's the sort of trick plants are famous for pulling. For some reason, ploidy matters a lot more with most animal species than it does with plants. I wonder how becoming triploid facilitated asexual reproduction in these crayfish?
I suspect we're going to learn a lot if we study this new species carefully!
There are insect species and lizard species that reproduce by parthenogenesis, so I'm not completely surprised that crayfish can manage this trick. The advantages are obvious. I wonder if anyone has compared the new species' DNA to the original parent species and nailed down what mutations occurred to allow the new mode of reproduction. I also wonder if the marbled crayfish can still reproduce sexually with a male slough crayfish to produce viable young.
It also has disadvantages. There is no more genetic diversity making them more vulnerable to disease and possibly other natural catastrophes.
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