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(a marbled crayfish)
An all-female mutant species of crayfish is taking over the world by cloning itself. I know, it sounds like the plot of a B-rated sci-fi movie. But it’s true, and it’s getting wildly out of control.
The marbled crayfish is an invasive freshwater species suspected to have been created through an accident in a German aquarium around 1995. The entire global population of marbled crayfish has been traced to a single female that was born with the ability to reproduce without having its eggs fertilised by males. And henceforth, every marbled crayfish is female, and every egg laid is an exact clone of its mother.
This ability to reproduce quickly through asexual reproduction made the crustaceans popular in the aquarium trade, but when they found their way into the wild the crayfish got out of control. They’re now one of the most dangerous invasive species of crayfish around the world. The European Union has banned the species: It must not be sold, kept, distributed, or released to the wild.
But hold on. Clones are supposed to be at a disadvantage because they can’t adapt to changing environmental conditions. So how is the marbled crayfish so successful? The answer to this question might help us better understand ways to fight cancer.
Cancer cells and marbled crayfish are similar in that they both evolve clonally. Crayfish and cancer cells are also similar in that they are still capable of adapting to their environments through a process termed clonal evolution.
In traditional evolution, adaptations are created by sexual reproduction, because when two animals reproduce, their genomes are mixed up into new combinations in their offspring. However, both the crayfish and cancer cells seem to be able to produce clonally while still being adaptable via epigenetic mechanisms – chemical changes that affect DNA, but are independent of a creature’s genes. This is what allows the clones to inhabit such diverse environments, despite all sharing the same basic genetic code, and what allows cancer cells to develop immunities to cancer treatments.
Understanding the mechanisms of this type of adaptation can not only help us control the marbled crayfish population but also help engineer new treatments for cancer that are more effective.
Sources:
https://www.nytimes.com/2018/02/05/science/mutant-crayfish-clones-europe.html
https://www.theatlantic.com/science/archive/2018/02/attack-of-the-crayfish-clones/552236/
https://arstechnica.com/science/2018/02/mutant-crayfish-got-rid-of-males-and-its-clones-are-taking-over-the-world/
Photo credit: https://www.nytimes.com/2018/02/05/science/mutant-crayfish-clones-europe.html