Differentiation degree and developmental stability of Chionomys gud (Rodentia: Cricetidae) by nonmetric cranial traits

Abstract

The work describes the results of assessing developmental stability and the degree of differentiation in Chionomys gud within Protected Areas of the Central and Western Caucasus. We characterised developmental stability in Chionomys gud in different eco-geographical conditions by means of fluctuating asymmetry levels (FA nm) in a series of cranium phenes in four geographical populations. Thus we estimated the effect of environmental factors on FA nm levels. We registered the highest FA nm value for the sample from middle mountains of the Central Caucasus, i.e. the vicinities of the village Elbrus. The environment conditions of the given sample were the most stressful for the species (annual average temperature below 5°C and annual average precipitation below 1000 mm). Two-way ANOVA for factors «annual average temperature» and «annual average precipitation» verified a correlation between FA nm levels and complex effects of the two climatic factors. We evaluated the levels of interpopulation phenetic distances by the analysis of frequencies of phenes of nonmetric cranial traits in Chionomys gud populations. Maximum phenetic distances were revealed between geographically distant (over 300 km) populations of the Central and Western Caucasus. The degree of morphological differentiation of the samples from the Central Caucasus, which are apart at the absolute distance of 20-60 km, was less pronounced. Our results suggest that the level of phenetic distances is determined not only by the effect of territorial isolation, but also by climatic peculiarities of a particular locality.