Demographic and Morphometric Characteristics of the Moor Frog Rana arvalis from a Transformed Habitat in the Khanty-Mansi Autonomous Region—Yugra

Abstract

We analyzed the variations in the demographic and morphological characteristics of mature Rana arvalis individuals from natural and transformed habitats near Surgut. Female frogs from the transformed habitat were significantly smaller than males and significantly younger and smaller than females from the natural habitat. The direction of sex-related differences in both populations was the same as in most of the populations of the species that had been studied earlier. The low values of the mean body length (but not age) that were recorded in populations living near the northern range limit correspond to the general trend of body size variation in adult frogs in relation to the length of the season of activity throughout its vast range. Sex-related differences in most of the studied characteristics were due only to the variations in body size; few characteristics are not dependent on the body size, and these characteristics are most likely to determine mating success in males. We observed no morphological differences related to different environmental conditions in both neighboring populations. The relative femur and shin lengths were significantly larger in males than in females not only in the two Surgut populations but in all other populations studied earlier; these differences were not related to the greater body length in males. A tendency toward an increase in the relative head width and a decrease in the relative femur and shin lengths from the southern to the northern populations was observed in both sexes; this tendency was related to neither the mean age nor the body length.