Geneticists unravel secrets of super-invasive crayfish

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By Ewen Callaway

Molecular biologists have sequenced the genome of an invasive species of crayfish that can reproduce without mating and is spreading rapidly across Madagascar. The marbled crayfish (Procambarus virginalis) was first spotted in aquariums in Germany in the 1990s. Now, DNA sequencing suggests that the species is probably the product of two distantly related members of a different crayfish species, a team reported on 5 February in Nature Ecology and Evolution1.

The marbled crayfish has already been banned in the European Union and some parts of the United States because of the threat it poses to freshwater ecosystems. The species has now spread into the interior of Madagascar and risks crowding out seven native crayfish species. “This is a very aggressive population,” says Frank Lyko, a molecular biologist at the German Cancer Research Center in Heidelberg, who co-led the study. “If the marble crayfish continues to explode at its current pace, it will probably outcompete endemic species.”

The marbled crayfish carries three copies of each chromosome, instead of the usual two2. Lyko and his team sequenced the genome of a single individual from a laboratory strain known as Petshop. Its DNA revealed a surprise: it had two different genotypes at many places of its genome. The best explanation for this pattern, says Lyko, is that two of the chromosomes are nearly identical in sequence, but the third differs substantially.

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1 COMMENT

  1. @OP – The marbled crayfish carries three copies of each chromosome, instead of the usual two2.
    Lyko and his team sequenced the genome of a single individual from a laboratory strain known as Petshop.

    I have often warned about the dangers of invasive species, which do not have the natural restraints from a balanced native ecosystem, or the restrictions of quarantine regulations!
    There seems to be a bit of natural mutant genetic engineering here – after humans allowed two species to hybridise – and then distributed the clones all over the world!

    http://www.bbc.co.uk/news/world-43032061

    A mutant species of all-female crayfish taking over the world is not the latest science fiction film but a real life environmental thriller.

    A new study has found that marbled crayfish are multiplying rapidly and invading ecosystems across the world.

    The ten-legged pests are descended from one single female with a mutation allowing it to reproduce without males.

    These self-cloning ladies are found for sale in North America, despite a warning against keeping them as pets.

    Ah! The home of “free” enterprise – and damn the cost to the planet and its ecosystems!

    Sales of the six-inch creature are already banned by the European Union.

    Now officially a separate species, the marbled crayfish can been found in the wild in Japan, Madagascar, multiple European countries and the US.

    The new study published in Nature, Ecology and Evolution describes the invasive species as a threat to wild ones, particularly seven native species in Madagascar.

    “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.

    Dr Stein, who is a neurophysiologist at Illinois State University, told the BBC that they compared 11 marbled crayfish, spread through the pet trade to four locations on three continents.

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