On the issue of adaptive reactions of the blood system of competing species of turtles <i>Emys orbicularis</i> and <i>Trachemys scripta</i> (Emydidae)

Abstract

A comparative analysis of the leukocyte composition of the blood of Emys orbicularis and Trachemys scripta from the Samara Zoo was carried out. Statistically significant interspecies sex differences in the content of granulocytes (heterophiles, basophils and eosinophils) in the blood were established. The proportion of agranulocytes in the blood of both species was the same. Multivariate analysis of variance revealed a significant effect of species, sex, and their interaction on the leukocyte composition of the blood of turtles. At the same time, males of E. orbicularis differed from males of T. scripta by an increased content of heterophiles in the blood, and females differed from females by an increased content of heterophiles and a decreased content of basophils. An analysis of leukocyte indices revealed a more active component of the nonspecific natural resistance of the organism of E. orbicularis females compared to males and females of T. scripta. In captivity, E. orbicularis experienced greater stress relative to T. scripta, as evidenced by an increased value of the index of the ratio of heterophils and lymphocytes and a lower content of eosinophils. With an increase in body size, an increase in the relative content of lymphocytes in the blood of T. scripta females and an increase in stress resistance were noted, while in E. orbicularis such a specific immune reaction was not observed. We believe that the species-specific adaptive reaction of the blood system gives competitive advantages to the spreading exotic species T. scripta, which potentially threatens natural populations of E. orbicularis.