Correlations of reproductive indices of water vole females (Arvicola amphibius) with morphometric and hormonal characteristics

Fluctuations in water vole population size depend on abiotic and intra-population factors affecting the physiological condition of females. The relationship between reproductive success variability and morpho-physiological indices of females during pregnancy is studied quite poorly. In standard vivarium conditions, the morphometric and hormonal indices of females were assessed at different terms of pregnancy (first trimester—days 4–7, second trimester—days 8–14, third semester—days 15–20), and their relationship with potential and realized fertility and embryonic death rate was examined. The general regression model was used for the data analysis. Positive correlations were found between the potential fertility and the female body mass at mating, condition index, white adipose tissue index, and blood testosterone level. The reproductive indices under study were independent of the blood thyroxin level. A positive correlation was established between the level of embryonic loss and the liver and lung indices. Liver and spleen are essential for the maintenance of the female body mass homeostasis during the reproductive period.