Vladimir A. Yaskin

Lomonosov Moscow State University | MSU · Department of Vertebrate Zoology

Age-related variations in the hippocampus mass in the late postnatal ontogeny of bank voles (Clethrionomys glareolus) from the spring and autumn generations are considered in a comparative aspect. The mass of the hippocampus of the spring voles increases regularly over their short life cycle and approaches the values maximum for the species at two...

The age (in late postnatal ontogenesis) and seasonal variability of the brain mass of red voles (Clethrionomys rutilus Pall.) from diÈerent seasonal generations of a natural population from western Siberia are considered. Specific features of brain growth in red voles of early and late broods have been established. The growth of the brain of early...

A relatively rapid method for studying the variability of the morphology of small mammals-brain is proposed. This method was developed to process the zoological material when investigating the intraspecific variability. The essence of the method consists in the evaluation of mass and size of major brain divisions (bulbus olfactorius, forebrain, neo...

Sexual dimorphism of absolute and relative hippocampus mass was studied in bank voles (Clethrionomys glareolus) from two natural populations (West Siberian and Moscow regions). Overwintered males and females of the autumn generation captured in June were compared. When compared to other brain regions (bulbus olfactorius, neocortex, striatum, paleoc...

Male and female bank voles (Clethrionomys glareolus) were compared with respect to seasonal variation in hippocampus size and dynamics of spatial behavior during the annual population cycle. The winter decrease in the size of the hippocampus (the brain region involved in the processing of spatial information about the environment) in young autumn-b...

The hippocampus of mammals and birds is involved in the processing of spatial information about their environment. Its size positively correlates with spatial activity with home range size in particularly if closely related species in both mammals and birds are compared. Can this pattern also be seen in ontogenesis, the individual life of animals,...

The hippocampus is involved into the processing of spatial information on the environment, and its size is known to correlate positively with the spatial ability of mammal and bird species. The aim of the study was to find out whether such regularity is also manifested in ontogenesis during seasonal dynamics of the spatial behavior typical for many...

The variability of the brain-case volume in the red vole Clethrionomys rutilus was studied on the basis of the collection of the Zoological Museum of the Moscow State University. The possibility of using the small lead shot (1.25 mm in diameter) for measurement of the brain-case volume in the red vole is shown. The length, height of cranium between...

The locomotor activity of the common vole sibling-species (Microtus rossiaemeridionalis, 2n = 54; M. arvalis, 2n = 46) from natural sympatric populations of Moscow region were studied by the "open field" test. The brain and hippocamus mass of M. rossiaemeridionalis are larger than those in M. arvalis. In the field, the locomotor activity in M. ross...

The surveys of distribution and population density of the Black Sea dolphins, Delphinus delphis, Tursiops truncatus and Phocaena phocaena, were carried out from ships in 1985-1987. The data on frequency of occurence of the dolphins in different parts of the sea and on school size distribution are presented. The mean number of individuals per 100 km...

A comparative morphological analysis of brain in sympatric sibling species of Microtus rossiaemeridionalis (In = 54) and M. arvalis (2n = 46) was conducted on the material from one geographical point (Zvenigorod region, Moscow district). The brain mass in M. rossiaemeridionalis (514 + 6,8 mg in males; 490 + 9,3 mg in females) was significantly grea...

A comparative study of seasonal-age dynamics of brain size in six small mammal species, Clethrionomys glareolus, C. rutilus, Microtus oeconomus, M. gregalis (Rodentia); Sorex araneus, S. minutis (Insectivora) has been carried out. The analysis of seasonal changes in brain weight confirms the existence of autumn-winter regression of brain weight, wh...