Reproductive characteristics of sand lizard (Lacerta agilis Linnaeus, 1758) females in northern limit of species distribution in the Ural mountains

The study of reptile’s reproductive biology is one of the most- searched problems in herpetology. For the first time the reproductive parameters of the sand lizard (Lacerta agilis Linnaeus, 1758) were studied in the Middle Urals on the example of the northern populations of occidental and oriental macroslopes of the Ural ridge. The fecundity of females, the size of eggs, and the peculiarities of clutches localization were analyzed in the context of the energy optimization for reproduction. The study areas are located in the Middle Urals in the southern part of Sverdlovsk region. The material was collected in 2011–2013. The study included 50 pregnant females and 206 clutches of the sand lizard. The length and width of eggs were measured to calculate their volume. Statistical data processing was carried out with the help of programs MS Excel 2007 and Statistica 8.0. To reveal possible population differences, ANOVA was carried out. To determine the correlation ratios, Pearson correlation coefficient was used. As a result, the negative correlation between the egg volume and total fecundity was revealed. Besides, positive correlation between the egg volume and female’s body size was identified for the sand lizard population inhabiting the oriental foothill. In addition, significant differences between the reproductive strategy of the reptiles inhabiting the occidental and oriental foothills were found. For instance, the occidental lizards have larger number of eggs in the oviducts with relatively small egg size. The opposite trend was detected for urban oriental lizards. The female’s size and egg volume enlargement together with total fecundity decrease appear to be related to the increase in climate continentality from occidental up to the oriental foothills of the Urals. The results show two ways of sand lizard reproductive strategy. The first way with larger fecundity is typical for occidental reptiles. The second way with larger egg size is true to oriental reptiles of the urban population. The optimization of energy consumption for reproduction is realized at the population level.