Comparative study of thermoregulatory and thermogenic characteristics of three sympatric rodent species: The impact of high-temperature acclimation

Ambient temperature is one of the important factors affecting the survival of small mammals in the wild and different animals have different ways of regulating when face the same environmental temperature and different temperatures will also make the same species adjust the energy budget. Therefore, it is helpful to further understand the survival and adaptation patterns of different animals to study the different adjustment modes of animals in the same region in the face of high temperature environment.

In the present study, three rodents, Apodemus chevrieri, Eothenomys miletus and E. olitor, were exposed to a high temperature (T_a) of 30°C for 28 days. And then body mass, body temperature (T_b), resting metabolic rate (RMR) and thermal conductance (C) were measured at Ta from 5°C to 35°C.

The results showed that Tb of all three mammals increased significantly with the increase of T_a. And thermal neutral zones (TNZ) among three animals were all 25°C-30°C. Moreover, RMR increased with the increase of T above the upper critical temperature Within the range of 30°C to 35°C. C values in three mammals maintained stable within the T_a of 5°C-25°C, which increased with the increase of T_a above 25°C. All of the results suggested that three sympatric rodent species raised their T_b, narrowed their TNZ and changed C values to adapt to the high temperature. Moreover, change amplitudes of thermoregulation characteristics in E. olitor were small, indicating that E. olitor may have the strong adaptability under high temperature acclimation.