Some results of molecular phylogenetic studies of Baikal endemic invertebrates

Abstract

Baikal and the fauna inhabiting it became an object of systematic evolutionary studies more than a century ago. With the development of the methodical arsenal of biology, almost all approaches were also used to clarify the origin of Baikal’s population. The current review is mainly devoted to the results of using the molecular phylogenetics methods. The exceptional taxonomic wealth of the lake, colossal diversity of biotopes, and wide range of knowledge about different aspects of Baikal’s ecosystem functioning allow us to study such details of speciation mechanisms that are much less accessible in other circumstances. The main common features of modern evolutionary processes in the groups of invertebrates that are rich in species consist in the fact that, at first, most of them are young relative to Baikal and, second, in the fact that the speciation occurs sympatrically, since in spite of its size, the geological history of Baikal lacks episodes of its subdivision long-term enough for allopatric speciation. The reproductive barriers were most likely generated according to the rather complex scenarios developed under the effect of global climatic processes. This resulted in nuclear and mitochondrial introgressions. As a result of this, it is possible that intermediate forms of the organisms are widely distributed in Baikal, and it is very difficult to determine the taxonomic status of many of them. The almost complete absence of experimental evidence of the coevolution of species that are ecologically closely related to each other was also an interesting peculiarity. The results of evolutionary studies mainly devoted to bouquets of species (monophyletic groups of organisms that ensure the exclusively high species diversity of Baikal and the mechanisms of whose development remain largely mysterious) were considered in the review.