Contingency Variability of Morphogenetic Stability Indicators in Root Vole Populations with Ecogeographic Environmental Factors

Abstract

The bilateral asymmetry of the morphotypes m1 of the root vole Alexandromys oeconomus Pallas, 1776 from different parts of the range has been analyzed from morphogenetic positions. The material from the collection of the Institute of Systematics and Ecology of Animals, Siberian Branch, Russian Academy of Sciences (Novosibirsk), is used. A total of 2314 pairs of morphotypes m1 have been studied on the left and right rami of the mandible of voles. Seventeen different morphotypes and 70 different combinations of them are identified, of which 13 are symmetrical and 57 are asymmetrical. The data of bilateral asymmetry of morphotypes for each sample is presented in the form of square contingency tables. Based on these tables, the information-entropy parameters of the samples are calculated, in accordance with which the eco-geographic factors of the habitat are put. The 2B–PLS method is applied to the matrices after standardization. Two significant directions of contingency variability of the information-entropy parameters of the samples and eco-geographic factors of the environment have been identified. The first direction, latitudinal, is associated with a decrease in the Shannon entropy and fluctuating asymmetry in the northern samples of the root vole. Thus, the northern samples have a higher degree of morphogenetic stability compared to the southern ones. The second—the longitude direction—is highly correlated with the increase in altitude above sea level from west to east and is accompanied by a decrease in the values of the Cohen coefficient, Shannon information, and an increase in fluctuating asymmetry. This indicates a lower degree of morphogenetic stability of the eastern samples compared to the western ones. The approach we use complements the classical concept of the “epigenetic landscape” with the ability to take into account the influence of the environment. This is important in the practical use of asymmetry indicators for assessing the “health of the environment,” especially when determining the natural background for populations of the “ecological periphery” of the areal.