As marmorkrebs became more popular, owners grew increasingly puzzled. The crayfish seemed to be laying eggs without mating. The progeny were all female, and each one grew up ready to reproduce….
For nearly two decades, marbled crayfish have been multiplying like Tribbles on the legendary “Star Trek” episode. “People would start out with a single animal, and a year later they would have a couple hundred,” said Dr. Lyko.
Many owners apparently drove to nearby lakes and dumped their marmorkrebs. And it turned out that the marbled crayfish didn’t need to be pampered to thrive. Marmorkrebs established growing populations in the wild, sometimes walking hundreds of yards to reach new lakes and streams…
The scientists concluded that the new species got its start when two slough crayfish mated. One of them had a mutation in a sex cell — whether it was an egg or sperm, the scientists can’t tell.
Normal sex cells contain a single copy of each chromosome. But the mutant crayfish sex cell had two.
Somehow the two sex cells fused and produced a female crayfish embryo with three copies of each chromosome instead of the normal two….
It grew and thrived. But instead of reproducing sexually, the first marbled crayfish was able to induce her own eggs to start dividing into embryos. The offspring, all females, inherited identical copies of her three sets of chromosomes. They were clones.
Now that their chromosomes were mismatched with those of slough crayfish, they could no longer produce viable offspring. Male slough crayfish will readily mate with the marbled crayfish, but they never father any of the offspring.
This Mutant Crayfish Clones Itself, and It’s Taking Over Europe
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