Since its discovery in 1995 in Germany, the marbled crayfish has spread across Europe and into Africa in huge numbers 😉 “They eat anything—rotten leaves, snails or fish broods, small fish, small insects,” says Frank Lyko, a molecular geneticist at the German Cancer Research Center in Heidelberg 😁 “This crayfish is a serious pest,” adds Gerhard Scholtz, an evolutionary biologist at Humboldt University in Berlin, who has tracked its rapid spread across the globe, including Madagascar, where its success threatens the existence of the seven crayfish native to that island country. The European Union bans the sale, distribution, and release of the species.
Gerhard Scholtz, a zoologist at Humboldt University Berlin, kept one female captive in a tank in order to solve this mystery. The female is laying eggs, despite not having male spermatophores in previous copulations. However, the female might still be reproducing via other means–the crayfish may have used both. male and female reproductive organs. Scholtz’s group collaborated with biologists from the University of Heidelberg to examine the reproduction system of laboratory crayfish population. The only thing they found was ovaries. They were able to confirm that they could only produce female offspring, which is a rare technique known as parthenogenesis. Steven Sanchez, Onitsha (Nigeria) amended the above on August 31, 2020
Alexandrea Kuhn at theatlantic.com Additional information is available. The marbled Crayfish was not only found in German aquariums, scientists quickly realized. They were self-replicating and aggressive intruders. “Every single one has the ability to reproduce. Every single one could start a new population,” says Zen Faulkes, a crustacean researcher at the University of Texas at Rio Grande Valley who keeps a map of marbled crayfish invasions. Marbled crayfish can be purchased online, even though they have been banned by the European Union. It has been found in nature in Germany, Slovakia, Sweden and Japan. “We’re being invaded by an army of clones,” says Faulkes. (Repeated by Alan Hill of Cali, Colombia, March 3, 2020).
Based on an article atlasobscura.com, over the past five years, Lyko and his colleagues have sequenced the genome of the marbled crayfish, publishing their findings this week in the journal Nature Ecology & Evolution. It appears that the crayfish are the result of one drastic mutation in a slough crabfish. The species is found in Florida, Georgia and Florida. Three decades ago, two slough-crayfish crossed. Each sexcell has one copy each of the chromosomes in normal reproduction. But there was something awry with one of these initial two crayfish—a mutation that left it with two copies in its sex cell. The offspring survived and was in excellent condition. Amazingly, the offspring had three copies of each gene and was able to reproduce without any assistance from a man. Last modified by Genice McClendon, Panama City, Panama.