Distribution limits of forest-dwelling small mammals (Eulipotyphla, Rodentia) in the Crimean Mountains

Abstract

Concluding data on distribution limits of small mammals that have isolated geographic ranges in the montane forest zone of the Crimean Peninsula are presented. The analysis is based on data collected for forty years of mammal research in the Crimea, with a total sampling effort of 600 000 trap-nights and more than 63 000 trapped specimens of small mammals. The article considers the geographic range of two insectivore species of the family Soricidae (Neomys anomalus and Sorex pusillus) and three rodent species that belong to the families Muridae (Sylvaemus tauricus and S. uralensis) and Cricetidae (Microtus obscurus). These are forest-dwelling species that find food, shelter and other favourable conditions necessary for full and permanent existence of their populations in forest communities. This group of Micromammalia is of the greatest interest from the viewpoint of zoogeography and evolution since they have been geographically isolated from their main range for thousands of years. Their gene pool therefore preserved both ancestral genetic material and new alleles that have been amassed during the entire period of isolation and have been filtered by natural selection. Range boundaries of these species have been affected by various environmental components that have been acting as main limiting factors. These are hydroclimatic factors (humidity and moisture that determine meso- and microclimatic parameters of biotopes), floristic factors (dominating flora composition that determine trophic and topic features of local animal populations), and landscape and edaphic factors. Neomys anomalus and Sorex pusillus are stenotopic and hygrophilous species that inhabit the wettest biotopes of mountain forests of the Crimea thus they have the smallest geographic ranges. The geographic range of Sylvaemus tauricus is wider and is related to the distribution of oak-beach forests. The species Sylvaemus uralensis and Microtus obscurus are the most eurytopic and their geographic range expands even to the Crimean Lowland in a north-eastern direction. Natural and climatic conditions that are present in the montane and piedmont zones are optimal for the species S. uralensis and M. obscurus, which are thus abundant and dominating here among small mammals.