Tomsk school of evolutionary cytogenetics of malaria mosquitoes

In this article we provide a brief overview of research in the main areas of evolutionary cytogenetics of malaria mosquitoes initiated in the 1960s at Tomsk State University. The threat of mass malaria in the Soviet Union was eliminated in the 1950s and 1960s. However, malaria mosquitoes were not destroyed and still remain potential or actual carriers of infectious diseases such as malaria and dirofilariasis. A great contribution to the study of the ecology of malaria mosquitoes in our country was made by the outstanding Russian zoologist and ecologist Vladimir Nikolaevich Beklimishev (1890-1962), who wrote the fundamental work "Ecology of the Malaria Mosquito" in 1944. In the 1950s and 1970s, the American zoologist James B. Kitzmiller (1918-1995) was very actively involved in the cytogenetics of malaria mosquitoes in North America. Using interspecific hybridization, he proved the relationship between the mosquito species of North America and Eurasia and the more ancient origin of the Nearctic group. Kitzmiller's works clearly demonstrated the relevance and timeliness of studying the paleoarctic group of mosquitoes using cytogenetic methods. The ideological inspirer of conducting cytogenetic research at Tomsk University was Tatyana Semenovna Pestryakova (1909-1996), who headed the Department of Invertebrate Zoology at TSU from 1964 to 1974 and had previously studied the ecology of Siberian malaria mosquitoes. Work on the study of the chromosomes of malaria mosquitoes of the Maculipennis group began with the support and participation of the head of the Department of Cytology and Genetics of TSU Nadezhda Nikolaevna Kartashova (19071998). The first published works were devoted to the characterization of the karyotype of Anopheles messeae of the Middle Ob region and the cytogenetic identification of sibling species of malaria mosquitoes An. maculipennis and An. messeae. Vladimir Nikolaevich Stegniy (1946-2023), together with Valentina Matveyevna Kabanova, was the first to use the cytogenetic method to describe a new species of mosquito -An. beklemishevi Stegniy & Kabanova, 1976, named in honor of V. N. Beklemishev. Studying the chromosomes of different mosquito species at different stages of development, V.N. Stegniy discovered that the spatial organization of chromosomes changes significantly during ontogenesis and speciation. It turned out that An. messeae has the largest range among the species of the Maculipennis group, covering almost the entire Boreal subregion of the Paleoarctic, and the greatest inversion polymorphism, which is a classic example of adaptive chromosomal polymorphism. The first works formed three main areas of research on the evolutionary cytogenetics of mosquitoes: 1) species composition and phylogenetic relationships of malaria mosquitoes; 2) reorganization of the spatial architecture of the malaria mosquito genome in ontogenesis and evolution; 3) population and ecological genetics of malaria mosquitoes. Reconstruction of the phylogenetic relationships of mosquito species is important for understanding how and when their genomes changed, and how this contributed to adaptation to new habitats and new pathogens, and also allows researchers to determine the geographical routes of migration and the order of speciation. The study established the geographic distribution, reproductive relationships, and chromosomal phylogenetic relationships in the Anopheles maculipennis species group. It turned out that An. beklemishevi is closest to the Eurasian species and separated from them ~20 million years ago. Thus, the common ancestor of An. beklemishevi and other Eurasian species could have migrated from North America to Eurasia when the Bering Land Bridge existed. The main malaria carriers evolved independently of each other in the Maculipennis group. These data make it possible to approach the study of the molecular genetic basis of the ability of mosquitoes of different phylogenetic lineages to effectively transmit malaria. Studies on the evolutionary cytogenetics of malaria mosquitoes, initiated at Tomsk State University in the 1960s, played an important role in the development of this field of science. They made it possible to significantly advance the understanding of the species composition and phylogenetic relationships of malaria carriers and other diseases. Studies of the spatial organization of chromosomes have provided new insights into the regulation of genomic activity during cell differentiation and the mechanisms of genome architecture reorganization in evolution. These achievements provide a basis for further study of the mechanisms of speciation and adaptation of malaria mosquitoes to changing environmental conditions and interactions with pathogens. The article contains 41 References. The authors dedicate this article to the memory of Vladimir Nikolaevich Stegniy, the founder of the scientific school for the study of cytogenetic mechanisms of evolution and adaptation of natural populations of animals and plants at Tomsk State University. The Authors declare no conflict of interest.