Diversity of regional complexes of mammals in Europe at the boundary between Pleistocene and Holocene

Analysis of the data of the paleontological chronicle, containing important information about the evolution of biological diversity at the turn of the Pleistocene and Holocene, is of great importance for understanding the historical patterns of formation of modern terrestrial ecosystems and the forecast of their changes in the future. The article deals with the general regularities of the evolution of the parameters of biological diversity in 11 regional complexes of mammals in Europe during their qualitative restructuring in the range of 50 to ~ 5 thousand years before present (BP) - marine isotopic stages MIS 3-MIS 1. Based on the results of modeling the evolution of the structure of the complexes, the time parameters of transition periods in the range of 18-6.6 thousand years ago were determined for each of them, the duration of which varied from ~1 to 5.6 thousand BP. The duration of this transition varied from ~ 1 to 5.6 thousand years. Three types of evolution of the complexes were identified and described. To study the evolution of biological diversity at the “initial stage” (Pleistocene), transitional stage and “final stage” (Middle Holocene) of complexes, the following parameters were determined: species richness, entropy, dominance index, redundancy, and Wilson-Shmida β-diversity index. In addition, the applicability of different models of rank distributions to describe empirical data and the correspondence of different models to different evolutionary states of faunal complexes were investigated. It is shown that the main content of the evolution of most complexes was expressed in the reduction of species richness/diversity and simplification of their internal structure, including, probably, the reduction of functional redundancy. The stability of the majority of European faunal complexes in the late Pleistocene was ensured due to the high species richness, the relative stability of ecological niches (specialization) providing high ecological functional redundancy with a wide mutual overlap of the latter. Based on the results of this study, we suggested that the loss of biological diversity and the simplification of functional relationships in the “species - environmental resources” system in the Holocene resulted in the decrease in stability of most regional complexes, but increased their ability to self-repair after external impacts.