Гетерогенність популяцій гризунів на термінальних фазах динаміки щільності

Abstract

<p>The population structure of populations of two vole species (Myodes glareolus Schreber, 1780 and Microtus subterraneus de<br />Selys-Longchamps, 1836) were analyzed towards the peaks and depressions of their dynamics of density. Field researches were<br />conducted throughout the first half of summer during 2000-2013. The sample was more than 800 individuals.<br />Reactions of populations of rodents to changes of living conditions during dynamics of the population are provided with speciesspecific<br />reorganizations of sex and age structure. On the basis of allocation of functional and physiological groups, comparison<br />of their contribution to changes of density of populations is carried out. Specifics of this approach consist that at allocation of<br />such groups as criterion the similarity of a functional condition of individuals connected with features of growth, development<br />and unity of a reproductive state is accepted.<br />Changes of living conditions during dynamics of population density, cause realization of species-specific population reactions<br />are being show. In population of a bank vole delay of intensity of reproduction in years of density peaks is reached due to<br />preservation of a considerable share of the wintered individuals. It is followed by simplification of age structure and change of<br />a sex ratio towards prevalence of females. The analysis of coefficients of a reproduction shows that the wintered individuals<br />provide 1/3 population increase. In years of the low density of an intensification of reproduction the maximum realization of<br />biotic potential of young animals promotes. Also as the buffer a large number of individuals who will enter at reproduction the<br />next year remains.<br />In population of pine vole the priority mechanism of regulation of reproduction is the effective date variation in a reproduction<br />of bulk of representatives of spring and summer generation. In the conditions of an overpopulation (density peak) the share of<br />animals who don't breed is maximum and exceeds quantity of breeding almost twice. The wintered individuals aren't enough<br />and they don't provide such essential contribution to a reproduction as at a bank vole. In depression phases the quantity of the<br />breeding voles of the current year of birth more than twice increases, they provide the further growth of population.</p>