Population density and immune function in Brandt's voles (Microtus brandti)

摘要

In order to determine the relationship between population density and immune function in Brand's voles (Microtus brandti), we investigated the effects of low (1 animal/cage), moderate (4 animals/cage) and high (8 animals/cage) density on the growth and immune functions of male and female adult Brand's voles from a long term, stable same sex groups. Body weight, spleen weight, testis weight, levels of serum antibodies and serum cortisol were measured. We found that: (1) final body weights and male reproductive organ weights decreased with increasing density; (2) female Brandt〖DK1〗's voles in the moderate and high density groups had better immune function than those at low density, but the immune functions of male individuals were not significantly affected by density; (3) density had no significant effect on the serum cortisol levels of both male and female voles. These results suggest that a long term stable and harmonious social environment does not necessarily cause social stress in Brandt〖DK1〗's voles. Population density can affect the growth, reproduction and immunity of Brandt〖DK1〗's voles and these effects differ between the sexes［Acta Zoologica Sinica 49(4):438-444,2003］.