In the forest-steppe area, carnivorous mammals are represented by species of different faunistic assemblages. This circumstance makes the study region a priority since the species of which faunistic assemblages prevail is of interest. Fifteen carnivorous species have been identified in the territory of Mordovia. Among them, the family Mustelidae predominates in terms of the number of species. The species are found in all geoecological districts, but their distribution is uneven. The most notable species in the region are located in coniferous and broad-leaved forests (40%) and species widely distributed in several natural areas (40%). 13% of the total number of noted species belong to the taiga fauna types. The steppe type of fauna is represented by only 7% of the total number of recorded species. For each geoecological region, the fauna features are given, and a list of rare and exciting species is given. The forest-steppe zone to which Mordovia belongs is compared by the fauna of carnivorous mammals with other regions from three typical faunal assemblages.
Andreychev, A. (2021). Proportion faunal assemblages of carnivorous mammals in geoecological districts of Mordovia, Russia. Biodiversitas. 2021. V. 22. № 10. P. 4625–4632

The new theory of vortex (ring) determinism, which focuses on the existence of internal causal sources, could not ignore the problem of the evolution of species of living organisms. According to Darwin's concept, the credit for the development of species belongs entirely to external conditions and random mutations of genes. This concept should be recognized as a product of philosophical objectivism in its purest form. And vortex determinism radically corrects the situation, simultaneously raising the banner of Lamarckism on the shield.

n one natural area, animals may have different distribution. In some areas they inhabit, and in other areas, they do not inhabit. Scientists have been working on this issue for a long time. In this study reports that the species composition and distribution of species varies depending on geoecological districts. Twenty-eight rodent species have been recorded in the territory of Mordovia. The largest number of species in the region belongs to those living in coniferous and broad-leaved forests (42.9%). In the second place in terms of representation are species widely distributed in several natural areas (28.5%). They are slightly inferior to the types of steppe fauna (25%). The taiga type of fauna is represented by only 3.6% of the total number of registered species. For each geoecological district, the features of the rodent fauna are given and rare species are identified. The forest-steppe region of Mordovia is compared in rodent fauna with other regions of Russia with different typical faunal assemblages.
Andreychev A. Proportion faunal assemblage of rodents in geoecological districts of Mordovia, Russia // Biodiversitas. 2020. V. 21. № 9. P. 3961–3968.