Some data on different ways of adaptation of rodents to changes in the habitat in mountain conditions

The article considers the differences in body weight and heart index in males of selected species of Muridae and Microtinae in the conditions of the altitude-belt structure of the mountain landscapes of the Caucasus. It was found that in widespread species (Apodemus uralensis and Mus musculus), the transformation of the heart index during the development of high altitude is characterized by multidirectional mechanisms. In the first species it actually does not change with increasing terrain elevation, whereas in the second species it increases significantly. While Apodemus uralensis exhibits features of eurybiont, Mus musculus demonstrates a change in the proportionsof the organism characteristic of widespread species during the development of the high altitude. The field mouse (Apodemus agrarius) shows low ecological valence. In the middle mountains, the ratio of body weight to heart weight decreases compared to the plain, which is probably one of the mechanisms limiting the distribution of the species in the Caucasus to the plain-piedmont area. The heart index of the studied species of Microtinae (Microtus arvalis macrocranius, Microtus socialis, Chionomys roberti) is significantly lower than that of Muridae (Apodemus uralensis, Apodemus agrarius and Mus musculus). In our opinion, this is due to the peculiarities of their nutrition and various motor activities. This pattern persists in mountain conditions.