All-female crayfish species that didn’t exist 30 years ago reproduces by cloning itself

All marbled crayfish originate from a single female that reproduced without a mate 30 years ago – making every member of this species a female, scientists say.

Researchers made the discovery after sequencing the genome – the genetic material present in a cell or organism – of the crustacean.

The scientists say that a genetic mutation may have caused a slough crayfish (Procambarus fallax) in an aquarium to reproduce asexually three decades ago, giving rise to an entirely new species – the Procambarus virginalis.

Since then, marbled crayfish – or marmorkrebs – have grown in numbers without any help from males. They reproduce asexually, essentially cloning themselves, in a process called parthenogenesis.

They are currently found throughout Europe and Madagascar, and are considered an invasive species.

Genome sequencing revealed the marbled crayfish to be a genetically identical.

Their genome contains 3.5 billion base pairs (chemicals that connect the complementary strands of a DNA molecule), making it 7% larger than the human genome.

Frank Lyko, from the German Cancer Research Centre, said: “We could detect only a few hundred variants in a genome that is larger than the human genome. That is an incredibly small number.”

Despite being born with the same genes, scientists say this crayfish has been able to adapt to diverse environments because of the way it expresses its genes.

The team believes studying the genetic make-up of the marbled crayfish could help scientists learn more about tumours – which also evolve by cloning and are capable of adapting to diverse environments.

Mr Lyko said: “Marmorkrebs is an animal that reproduces clonally and therefore represents a model of a central aspect in tumour development.

“Tumour genomes also evolve clonally, because they go back to a single original cell.”

The findings are published in the journal Nature Ecology and Evolution.