Formation of Interspecific Differences by Morphometric Characteristics of Common (Rana temporaria) and Moor (R. arvalis) Frogs

摘要

Froglets (juveniles), subadults and adults of the common (Rana temporaria L.) and the moor (R. arvalis Nilss.) frogs, collected in Moscow Province were studied. The interspecific differences in limb and head characters are formed in subadults (not infroglets) and later retained in characters used for distinguishing these species In the moor frog, allometric coefficients are close to 1 for the longitudinal dimensions of the head (head length, snout length, distance between snout tip and line connecting nostrils), and their relative values (indices) are greater than in the common frog. On the contrary, relative values of the head and snout width and distance between nostrils are smaller In the moor frog, sexual differences appear earlier, than in thecommon frog. The relative length of the forearm, thigh, shank, foot and the 4th toe is greater in the subadult males of the moor frog than in the females In the common frog, sexual differences appear in the maturing specimens, similar in size to the adult moor frogs: males have greater relative size of the arm and forearm than females. In both species, sexual dimorphism increases with size. Differences between the sexes are observed in all limb characters except length of the 1st finger and the inner metatarsal tubercle. The adult specimens of Rana arvalis differ from the same sex specimens of R. temporaria by smaller relative size of the arm and forearm. Adult males of the former species have bigger relative size of the thigh, foot and the 4th toe than in the males of R.. temporaria. Both species demonstrate rapid growth of limbs and slow growth of head parts in relation to body growth.