OK…stay with me on this one because it sounds like the script for a B-rated Sci-Fi movie and it is going to get a little technical. A voracious mutant 10-legged crustacean that reproduces asexually, escapes from an aquatic reproductive facility in Germany, and begins to take over the world by cloning itself billions of times over. It spreads across Europe and Africa causing destruction to ecosystems and threatening native aquatic species.
Sound too farfetched? Not really. This actually appears to be the strange-but-true story of the marbled crayfish. The marbled crayfish is now considered a detrimental invasive freshwater species suspected to have been created through a reproductive accident in an aquarium around 1995.
Now, via new technology and better genetic analysis capabilities, a re-look at the genome of the marbled crayfish suggests that this is exactly what happened. And, to make the story more like a Sci-Fi flick, the marbled crayfish has escaped controlled environments and is now reproducing in the wild and adapting to almost every type of environment.
Since its discovery in the wild in Germany about 15 years ago, the marbled crayfish has spread across Europe and into Africa in huge numbers. They are a very adaptable creature and they eat almost anything…fish eggs, small fish, snails, worms, small insects, even decaying leaves in the water.
“This crayfish is a serious pest,” said Gerhard Scholtz, an evolutionary biologist at Humboldt University in Berlin, who has tracked its rapid spread across the globe. It has even made the jump to Madagascar, where its success threatens the existence of the seven unique crayfish species native to that island country. The European Union has now totally banned the species. It must not be sold, kept, distributed, or released to the wild.”
Why is this coming to light now? It seems that a German biologist and cancer researcher, Frank Lyko, has been studying marbled crayfish. Why would a biologist be studying a six inch long crustacean? The answer is to reveal an unknown strategy for eradicating a similar cloning monster: cancer.
Five years ago, Lyko became interested in the marbled crayfish because he thought its newly evolved asexual nature might parallel how a normal cell division turns cancerous and begins generating clones of itself. He wanted to study the genomes of marbled crayfish to uncover basic mechanisms underlying epigenetics, the binding of molecules to DNA that can drive tumor growth and help cancer spread.
According to Science Magazine, Jean-François Flot, a genomicist working with the University of Brussels said, “In many ways, the invasive expansion of the marbled crayfish is analogous to a cancerous lineage spreading asexually at the expense of its host.”
The marbled crayfish is the only known crustacean that can successfully reproduce asexually. The all-female species makes clones of itself from eggs that have never been fertilized by sperm. These eggs are produced hundreds at a time. This can happen multiple times a year. It is almost an exponential increase for each crayfish, and then you can multiply that numbers by millions!
With the rapid expansion of the marbled crayfish spreading across much of Europe it appears that nothing can stop this sex-free species from taking over the world.
But we may not be doomed to a world full of marbled crayfish. While the ability to reproduce asexually may have some advantages in producing total numbers, it could also be an organism’s downfall. Sexually reproducing species mix their genes together into new DNA combinations with each new generation and thereby increase the odds of developing a defense against diseases. An asexually reproducing organism can’t do this!
When an organism like the marbled crayfish clones itself, i.e. makes an exact replica of itself, there is no gene sharing via combining/recombining of chromosomes. It is the sharing of genes that allows us to build up immunity to disease. The old adage of the survival of the fittest comes to mind.
All virus and bacteria evolve and change, ever so slightly, in order to keep on living. We see this with flu viruses every year. If a pathogen would evolve to be able to attack one marbled crayfish clone, then every other clone would be susceptible, too. Something as simple as a cold virus could wipe out every marbled crayfish in the world.
Sometimes real-world occurrences are stranger than Sci-Fi movies.