ALLOMETRIC GROWTH AND THE FORMATION OF SEXUAL DIMORPHISM IN THE ONTOGENY OF THE ROCK LIZARD, DAREVSKIA LINDHOLMI (SZCZERBAK, 1962)

Abstract

The genus of rock lizards Darevskia is an important model object for studying speciation processes in reptiles, in particular as an example of reticulate evolution. This genus includes not only bisexual but also parthenogenetic species. Its systematics and taxonomy are constantly becoming more complex, based on the results of molecular genetic, morphological, and ecological studies.There is very little information in the literature about the external morphology of the only aboriginal bisexual species of rock lizard in the Ukrainian fauna – D. lindholmi. In particular, there is almost no data on its age variability, changes in the size and proportions of the body and its parts in different age groups of heterosexual individuals. The study of these issues is important for the methodology of sample formation and research, since it is obvious that samples with different age and sex compositions may show different results regarding external morphological characteristics when compiling species descriptions. Therefore, the aim of this work was to study the characteristics of growth and the formation of sexual dimorphism in the ontogenesis of D. lindholmi and to determine the effectiveness of statistical analysis for correcting errors when comparing samples of individuals of different ages and sexes.The material for the study was 43 individuals of D. lindholmi from Crimea. Thirty-three characteristics of the size and proportions of the animals were used. The data were processed using factor and discriminant analyses. It was found that discriminant analysis allows each individual to be reliably assigned to a specific sex-age group and enables the formation of comparable samples for any comparative descriptions. The variability of morphometric characteristics in ontogenesis is 91,5% characterized by the first two principal components. The first accounts for 89,1% of the variance and has high factor loadings for all traits, indicating their correlated variability. There are practically no sex differences in most measured traits in Lindholm’s lizard. In terms of overall body size, males are larger than females, but with almost identical body sizes, they have larger absolute and relative head and limb sizes. With increasing age, the variability of body proportions increases. The influence of age on the variability of linear body dimensions is higher than on its proportions.