Genetic diversity studies of Baikal endemic sponges at the interspecies and population levels using high-resolution microsatellite markers

Lake Baikal, an ancient, massive lake in Siberia that holds 20% of the world’s fresh water reserves, is a unique center of speciation. Changes in the lake’s ecosystem in recent years require comprehensive monitoring activities to track the continuously evolving situation. Sponges are bioindicators of the state of aquatic ecosystems, and in Lake Baikal sponges are represented by both cosmopolitan and endemic species. However, the study of intra- and interspecific relationships between endemic sponges is complicated by the fact that standard molecular genetic markers are not suitable for these purposes. In this regard, the search for suitable high-resolution molecular genetic markers is especially relevant. Here we report on the development of a set of universal microsatellite markers that allows the interspecific relationships between Lake Baikal endemic sponges to be studied. We tested the effectiveness of this set of microsatellite markers on representatives of four endemic sponge species and achieved a reliable separation of representatives of all four genera of the endemic sponge family Lubomirskiidae. This is the first report of a set of highly variable molecular genetic markers that has been developed specifically for the study of interspecific relationships between Lake Baikal sponges. This set also has the potential to be a marker for species identification, which is important for monitoring activities in connection with events of mass death and diseases of sponges in Lake Baikal. The described approach can be used to study endemic sponges from other ancient lakes. It has great potential for use in the development of universal markers for identifying groups of closely related species.