Multilocus phylogeography of the European ground squirrel: cryptic interglacial refugia of continental climate in Europe

The theory of classical and cryptic Pleistocene refugia is based mainly on historical changes in temperature, and the refugia are usually defined within a latitudinal gradient. However, the gradient of oceanic–continental climate (i.e. longitudinal) was also significantly variable during glacial cycles with important biotic consequences. Range‐wide phylogeography of the European ground squirrel (EGS) was used to interpret the evolutionary and palaeogeographical history of the species in Europe and to shed light on its glacial–interglacial dynamic. The EGS is a steppe‐inhabiting species and the westernmost member of the genus in the Palaearctic region. We have analysed 915 specimens throughout the present natural range by employing mitochondrial DNA sequences (cytochrome b gene) and 12 nuclear microsatellite markers. The reconstructed phylogeography divides the species into two main geographical groups, with deep substructuring within both groups. Bulgaria is the centre of the ancestral area, and it also has the highest genetic diversity within the species. The northernmost group of the EGS survived in the southern part of Pannonia throughout several glacial–interglacial cycles. Animals from this population probably repeatedly colonized areas further to the north and west during the glacial periods, while in the interglacial periods, the EGS distribution contracted back to this Pannonian refugium. The EGS thus represents a species with a glacial expansion/interglacial contraction palaeogeographical dynamics, and the Pannonian and southeastern Balkanian steppes are supported as cryptic refugia of continental climate during Pleistocene interglacials.     

First evidence for active carnivorous predation in the European ground squirrel

acta ethologica - The Sciuridae family is generally referred to as herbivorous and occasionally omnivorous. Although sciurids are known to opportunistically feed on carcasses of other vertebrates...     

Principles of the structuro-functional organization of the hemomicrocirculatory bed of the intramural nervous plexuses of organs of the gastrointestinal tract of mammals

The work deals with one of the least elaborated aspects on the system of microcirculation and is performed, taking into account the functions of histo-hematic and intertissue barriers. For this certain new original investigation methods have been developed, adequate to the problems discussed. The module principle of organization with a distinct functional specialization of the ganglionar and truncal vascular micromodules has been stated. The working principle of each module is based on functional interaction of the intra- and extraneural capillary systems; this is ensured by mechanisms of the blood stream redistribution: by arteriolar, precapillary and prevenular sphincters and by pathways of the shunt blood stream. A high stability of the blood stream in the vascular constructions studied is explained as a possibility of counterstream gas exchange between the arterial and venous blood in the truncal vascular micromodule.     

Appearance of the flutter on the pulse wave

This work deals with the liquid flow in an elastic blood vessel. The mechanism of the initiation of standing waves was studied. Results of model experiments, both on the hydrodynamic stand and in the aorta of the living dog are presented.