“An invasive freshwater species suspected to have been created through a reproductive accident in an aquarium.”

The marbled crayfish that clones itself


Wed, Feb 7th, 2018 11:00 by capnasty NEWS

According to ScienceMag, a marbled crayfish capable of endlessly reproducing itself asexually -- a genetic freak accidentally created in an aquarium in 1995 -- has been diligently taking over the world. Not sure why scientists are worried: in a few years — give or take — they should be all dead anyway.

As suggested by some preliminary evidence, the marbled crayfish has three sets of 92 chromosomes, not the usual two, and each set is essentially a version of the chromosomes belonging to the slough crayfish (P. fallax). Two of the three sets of chromosomes are virtually identical, but the third is different enough that Lyko’s team concludes the marbled crayfish likely arose from the mating of two slough crayfish from different regions of the world thrown together in an aquarium. One must have had an abnormal egg or sperm that retained two copies of its chromosomes instead of the usual single set that is in such germ cells, Lyko explains. The bringing together of the two distant slough crayfish enhanced the genetic variation within the new clonal “species.” Such a union “would never happen in the wild,” he asserts.

Schotz isn’t totally persuaded that the genomic pile-up happened inside an aquarium, versus two slough crayfish meeting in the wild. “It is mere speculation that it originated in captivity,” he says. But the analysis of marbled crayfish DNA from across Europe and Africa, he says, ”shows that all these crayfish are clones—with identical genomes the world over.”



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