Evolution of Central European regional mammal assemblages between the late Middle Pleistocene and the Holocene (MIS7-MIS1)

摘要

The evolution of species composition and species richness from the end of the Middle Pleistocene to the Middle Holocene (～200-5 ka, MIS7-MIS1) studied in two Central European bioregional mammal assemblages include 176 chrono-species. The study is based on the list of 745 palaeontological sites and 1604 dated localities. For each region, the descriptive models (non-metric multidimensional scaling technique used) of evolution were obtained for full mammal assemblages as well as particular mammalian "guilds" (carnivorous, large herbivorous, small herbivorous and insectivorous). The models for full assemblages revealed several properties of the evolution process: non-linearity, combination of stationary and nonstationary states, irreversible (evolutionary per se) and reversible changes, threshold like effects accompanying transitions between stationary and non-stationary states, and elements of adaptive dynamics in changing environmental conditions. The evolutionary trajectories of mammal "guilds" have the same properties but differ significantly from each other and their relative complexity is no less than the trajectories of full mammal assemblages. Hence, the evolution shows emergent property and irreducibility of complexity at different structural levels of an assemblage. Throughout MIS7-MIS1 the regional faunas responded to global climate changes (δ~(18) O used as temperature variable), but had various contents, directions, consequences mediated by current species composition and geographic positions in relation to the Saale and the Weichsel continental ice sheets. The study shows a time/spatial invariance (scale-invariant property) of species richness for the stationary states of fauna evolution (especially during MIS3), which is described by a power law function. A mammal assemblage evolution is discussed within the framework of concept of open non-linear self-organising complex quasi-deterministic system with an ability of adaptive behaviour. Internal organisation of such systems justifies their existence and evolution in the area at a borderline between order and chaos and thus their evolution is intrinsically unpredictable.