Geographical variation and sexual differences of body length and age composition in rana temporaria: the ontogenetic development and phenotypic trends

The analysis of literature data on the mean values of age and body length of adult individuals of widespread species Rana temporaria from about 70 spatially separated populations, including our published data, was conducted. The evident trend in population mean age increase with the decrease of the of activity season length was revealed as well as the absence of that trend in the mean body length, with the maximal mean value in body length being near central part of the range. Our explanation of non-linear trend in the mean values of body length does not contradict other models of geographic variability explaining the correspondence and discrepance with the Bergman rule. In addition our explanation corresponds to the revealed features of interpopulation variation in growth rate. The revealed trend of variation in the mean body length is resulted from both growth rate decrease and mean age increase with the decrease in the length of activity season. The relatively low mean values of body length in populations from south and southern-west borders of the range are explained not only by low mean age but by lower growth rate despite high length of activity season. The interpopulation variation in body length is determined not only by body length but by age composition differences both between and within population. Therefore, the direction and intensity of sexual differences have not distinct trends, and the correspondence to Rensch rule (in contrast to Bergman rule) is rarely observed.