In the late 1990s, a remarkable animal was discovered in the aquaria of German fish hobbyists: a type of crayfish that could generate eggs even if they had grown up in isolation from other crayfish. This crayfish was nicknamed "Marmorkrebs" in German, which roughly translates as "marbled crab", the species has yet to be given a formal scientific name. Marmorkrebs are unique among crayfish, lobsters, shrimp, and crabs: every individual is female and can reproduce without sex. Marmorkrebs are closely related to North American crayfish, but no Marmorkrebs have been found in the wild in North America, so the source of these crayfish remains a mystery. Marmorkrebs have since been introduced into the waters of Europe and Madagascar. Because Marmorkrebs reproduce rapidly (every individual can generate eggs), they could be a serious pest species whose introduction could threaten native species. In addition to their mysterious origin and potential to be an ecological threat, Marmorkrebs are an excellent new model organism for lab research. Marmorkrebs are easy to care for and reproduce at high rates. More importantly, because they reproduce without sex, daughters are genetically identical to their mothers. Thus, any genetic change made to a mother (e.g., mutation, transgenic techniques) will be passed along faithfully to the daughters, which would allow stable strains to be established for specific types of research. That all individuals are genetically identical is also highly desirable, as it removes genetic variation as a factor that has to be accounted for in experiments. For example, the white lab rats that many people know are white because they have been inbred in an attempt to make them as similar as possible. Marmorkrebs are highly promising for laboratory studies of development, gene expression, neurobiology, and ecological physiology. This project will help introduce Marmorkrebs to North American researchers.
