Syst. One animal can potentially raise a new population. Marbled crayfish inhabit freshwater environments, and have not successfully invaded ecosystems with higher salinity levels due to their reduced ability to reproduce and grow. Marbled crayfish has been spread by aquarists and the aquarium trade throughout the world. Madagascar isn’t quite at that point yet, but it’s on the path. The marbled crayfish (Procambarus virginalis) is a monoclonal, parthenogenetically reproducing freshwater crayfish species that has formed multiple stable populations worldwide. Marbled crayfish have been observed migrating across land. “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. Born 25 years ago from a total mystery, today the rapid growth of the female crayfish population has also spread throughout Europe and Asia. Native Range: Since the marbled crayfish originated in the pet trade, it does not exist anywhere as a wild native population. Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily. He wonders why there were two different populations of P. fallax in the same tank. The team did more-limited DNA sequencing of 49 individuals caught across the island. The marbled crayfish threatens to crowd out seven native species in Madagascar. The entire global population of marbled crayfish has been traced to a single female held in a German aquarium, which was born with the ability to reproduce without having its eggs fertilised by males. A preliminary examination of morphological characters suggested that the introduced Malagasy crayfish might be the so far undescribed Marmorkrebs (marbled crayfish) (Scholtz et al., 2003). The top panel picture shows an adult marbled crayfish (3 years old) with eggs. Delicious and low cost, it poses only one problem – it’s taking … reproduce parthenogenetically. Because of how threatening the species is to native species, the EU has placed a total ban on the crayfish. Res. Evol. To better understand the species’ spread, Lyko’s team sequenced the genomes of four other marbled crayfish, including from populations that have escaped from aquariums and colonized German lakes, and an individual from a market in Madagascar. If these cells were then fertilized by another individual living in the same aquarium, it would result in an embryo with three copies of its genome, says Lyko. We present the results of a socio-economic survey (n = 385) in three regions of Madagascar that vary in terms of when the marbled crayfish first arrived. Nature Ecol. The species might even have emerged in the wild. Here’s everything you need to know. In 2009, she met a man on a bus carrying a plastic bag full of them that he planned to dump into his rice fields in the hope of creating a sustainable stock, she says. The female population independently ensures the creation of offspring. The marbled crayfish population on Madagascar will have to be monitored closely to prevent any adverse impact on the unique local freshwater communities 43,44. So if it’s a mutant, does it taste the same as normal crayfish? The marbled crayfish (Procambarus virginalis) was first spotted in aquariums in Germany in the 1990s. Researchers have found that the marbled crayfish could out-compete seven native crayfish. Researchers have found that the marbled crayfish could out-compete seven native crayfish. RANJA ANDRIANTSOA A t first glance, the marbled crayfish (Procambarus virginalis), a medium-size decapod crustacean with a speckled brownish-green shell, seems rather unexceptional. How the first marbled crayfish gained the ability to reproduce through parthenogenesis is a mystery, says Lyko. Nature Molecular biologists have sequenced the genome of an invasive species of crayfish that can reproduce without mating and is spreading rapidly across Madagascar. Molecular biologists have sequenced the genome of an invasive species of crayfish that can reproduce without mating and is spreading rapidly across Madagascar. We present the results of a socio-economic survey (n = 385) in three regions of Madagascar that vary in terms of when the marbled crayfish first arrived. It is particularly prevalent in Madagascar where its rapid spread in less than a decade is because of its popularity as a cheap source of protein. Wait till dark, switch on head lamps, and wander into the shallows. While researchers haven’t yet sequenced the crayfish genome, some are now studying its strong capacity to adapt to different climates in different countries. The invasive crayfish is determined as the parthenogenetic Marmorkrebs (marbled crayfish) (Cambaridae: Decapoda) on the basis of morphological features and the fact that all collected specimens were females regardless of their size. The marbled crayfish is the only decapod crustacean that reproduces asexually, with the all-female species making clones of itself from eggs unfertilized by sperm. Distribution of marbled crayfish on Madagascar (as of March 2017). Malagasy people are perpetually looking for easy ways to make a living, and fishing for marbled crayfish satisfies the profitability requirement for a business, as it requires almost no initial investment – all this at ecological risk of crowding out seven native crayfish species. To allow us to provide a better and more tailored experience please click "OK". 54, 13–21 (2016). The crayfish’s arrival in Madagascar threatens the success of several different species of crayfish that are native to the island. In Madagascar, he managed to gain control of an area the size of Indiana in about a decade at the expense of endemic crayfish species. “The fact that natural marbled-crayfish populations have not been found in the wild does not mean that they do not exist,” he says.