Enlarge (credit: Ranja Andriantsoa)
It’s possible to infer many species’ origins from things like fossils and DNA sequences. But for one creature, we have a specific date: 1995. That’s when the first marbled crayfish appeared in a pet shop in Germany, mixed in with similar-looking animals that had originally come from streams in the US South.
When it came to selling pets, the marbled crayfish had a big advantage over its relatives: it doesn’t need males to reproduce. Instead, females are able to produce genetic copies of themselves, allowing any fish tank to become a factory for an army of crayfish clones. Now, researchers have confirmed that these clones have spread throughout Europe, gotten as far as Japan, and begun invading the streams of Madagascar.
Ostensibly, the publication that describes these results is about the completion of the genome for the marbled crayfish. And the genome is what has allowed researchers to confirm that crayfish from around the world are essentially clones. But the real story in Nature Ecology and Evolution is the evolution and global spread of an entirely new species in less than 25 years.
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