Фрактальный анализ пространственной структуры популяций наземных моллюсков

Abstract

Доведено можливість використання фрактального аналізу для характеристики просторової структури популяцій наземних молюсків. Показано, що характер просторової організації наземних молюсків має чітко виражений фрактальний характер. Ступінь фрактальності для різних видів залежить від їх екологічних особливостей і насамперед відбиває реакцію до негативної дії десикації. The aim of the research is to describe spatio-temporal organization of the land snail populations in terms of fractal geometry. The analysis of spatial structure of the land snail populations has been made with use of the sample area location in the form of a regular grid. The investigate fields have been located within a the Dnepropetrovsk state agrarian university research polygon (The Dnepropetrovsk region, vicinities of Ordzhonikidze) and the Prisamarsky research stationer named after prof. A.L.Belgard of the Dnepropetrovsk national university. The obtained results have been present in the form of patterns of the spatial organisation of snails which consider only presence/absence of individuals within sample areas.The value of the fractal dimension (DF) may be obtained on the basis of dependence of the patch sizes used for analysis and these patches number with snail presence. The estimation of the fractal dimension of the spatial patterns of the snail distribution has been assessed.Data revealed that type of the spatial structure for some populations may be considered as random (DFclose to 1,5), whereas for others as highly aggregated (DF close to 2,0). Similar values have been received earlier at the analysis of spatial distribution bivalvia and marine gastropoda. The fractal nature of spatial distribution proved to be true also by means of analysis of separate patches of the polygons investigated. For example, for the adult individuals of a land snail B. cylindrica on a field of № 1 (2010) fractal dimension is DF = 1,797. Whereas for a quartet of the conforming subfields the yield DF estimates varied from 1,706 to 1,802. For the adult of individuals of a land snail M. cartusiana (in the same place) fractal dimension is equal to DF = 1,675, and for a quartet of the conforming subfields – varied from 1,578 to 1,684. Thus, the investigated species of the land snails form of "spots" (correspond, apparently, to separate dems) which was in turn organized in "spots" of more high order.Xerophilous species have been found to form the aggregations distributed in space in not random mode more often than among the mesophilous ones. Hence, the land snail order corresponding to decrease in stability of snails and slugs to desiccation characterized by the change of fractal dimension of spatial distribution from DF→ 2 (highly aggregated distribution) to DF → 1 (hypodispersion). It is possible to assume that such type of spacing of slugs lead to development at them of ability to an autogamy and existence in the form of almost isolated genetical lines. The spatial organisation of the land snail had legiblly express fractal character. The fractal measure for various species depended on them ecological features and, first of all, reflected reaction to negative influence of a desiccation.