Intraspecific variation in hematological parameters and erythrocyte size among three populations of Batrachuperus tibetanus (Caudata: Hynobiidae)

Intraspecific variation is a common phenomenon in nature, but to date, research on such variation in hematological traits of urodeles remains scarce. To compare intraspecific variation in hematological traits among populations, and explore whether snout–vent length (SVL) and body mass influence hematological traits, hematological parameters and erythrocyte size in 58 mature Batrachuperus tibetanus specimens belonging to three populations (Xihe, Meixian and Taibai) in northwestern China were analyzed. There were no sexual differences in any hematological trait for all populations. No hematological traits differed significantly between the Meixian and Taibai populations, but significantly lower values of erythrocyte count (RBC), hemoglobin (Hb), hematocrit (Hct), erythrocyte length (L), and erythrocyte area (A), as well as a significantly higher leukocyte count (WBC) were observed in the Xihe population compared with the other two. Linear regression analyses showed that significant relationships were present between SVL and Hb, RBC, Hct, and L; and body mass and Hb, RBC, Hct, and L. However, SVL and WBC were negatively correlated. Only L differed significantly among populations when accounting for the effects of SVL and body mass. Hb, RBC, WBC, and Hct variations among populations possibly contribute to differences in SVL or body mass, and erythrocyte size (L and A) variations are perhaps attributable to differences in lower Hb, RBC, and Hct; these variations are not the result of differences in habitat variables. Our results provide a foundation for understanding physiological intraspecific variation.