Home – Home – Jornals – Contemporary Problems of Ecology 2022 number 4

Two physico-climatic factors that were both distant and recent prerequisites and a trigger for the transformation of a clone of the ancestral pseudotuberculous microbe Yersinia pseudotuberculosis O:1b, the causative agent of Far East scarlet-like fever (FESLF), into a population of a derivative of the plague microbe Y. pestis are considered. A distant prerequisite was the aridization of the Central Asian landscapes in the second half of the Cenozoic and the formation of the Gobi arid zone. Arid conditions in Central Asia led to the formation of adaptive species-specific protective behavior in the Mongolian marmot-tarbagan ( Marmota sibirica ) during the installation of a wintering burrow plug, which subsequently contributed to the mass infection of FESLF animals during hibernation in an aberrant (traumatic, non-alimentary) way. The recent prerequisite and real trigger for the speciation of Y. pestis was the onset of the last maximal (Sartan) cooling in Central Asia at the turn of the Pleistocene and Holocene, 22-15 thousand years ago. Freezing of the Mongolian marmot’s wintering burrows caused a behavioral shift in the larval population of the marmot flea Oropsylla silantiewi - a transition in the cold winter-spring months of the year from saprophagy in the nest lining of burrows to hematophagy on the bodies of sleeping animals. Larval scarifications in the oral cavity of sleeping marmots became the entrance gate for a unique traumatic FESLF infection. The constellation of climate change, the heterothermic (and, accordingly, heteroimmune) state of family groups of sleeping marmots, year-round reproduction in the wintering burrows of the flea O. silantiewi , together with behavioral shifts in marmots and fleas caused by climatic changes, led to the formation in the parasitic system of “ Marmota sibirica - O. silantiewi” of conditions in which the transformation of the FESLF microbe into a peripatric plague pathogen took place. Thus, the different climatic changes in the Cenozoic led to a change in the behavior of the Mongolian marmot and later the fleas parasitizing it, and the change in the behavior of marmots and fleas caused the transformation of a clone of a pseudotuberculous microbe into a population of the plague microbe.