Evolution of non-marine ostracoda
One of the oldest living aquatic habitats of our planet, ostracoda, have managed to survive and evolve during the years under very difficult environmental conditions. The three main lineages of non-marine ostracoda, namely Darwinula stevensoni, Limnocythere inopinata and Eucypris virens diverged almost 400 million years ago and evolved differently. Studying their reproductive modes along with their geographic spread may provide a better insight on their evolution mechanisms and their corresponding ecosystems. Urged by this research, this project analysed the distribution of reproductive systems of ostracoda in Europe and observed a large diversity between species and genera. While L. inopinata and Eucypris virens comprise clusters of clones with specialised groupings, D. stevensoni involves a more generic genotype. Using various strategies the project researchers also analysed the genetic and morphological variability of species. Eucypris virens displays the highest morphological and genetic variability (more than 200 clones) whereas D. stevensoni the lowest genetic variability (only few clones). The valuable results provide a better understanding of the factors that determine the reproduction of non-marine ostracoda that will facilitate the ecology studies of extant and extinct populations when monitoring ecosystems. Additionally, the morphological recognition of specialised clones, such as those found in L. inopinata may represent a refined method of palaeo-environmental reconstruction and climates. Most importantly, the observed integrity of the nuclear genome of the ancient asexual darwinulid ostracods led to a well-established conclusion that they include a general-purpose genotype. In contrast to evolution laws, this genotype has been kept through the years most probably thanks to very efficient DNA repair systems whose further study is expected to advance cancer research.