[Animal immunocompetence and its effect on population regulation and life history trade-off]

Immunocompetence is a common conception in biomedical and animal sciences, and refers to the ability of organisms against diseases. In recent years, a new field, ecological immunology, has been received much attention, which deals with the variation of immunocompetence in wildlife by immune methods. This paper introduced the conception of immunocompetence, the factors affecting its performance, and its roles in regulating animal population dynamics. Some hypotheses on population regulation in small mammals, such as immunocompetence handicap hypothesis, immunocompetence selection hypothesis and winter immune enhancement hypothesis were summarized. The relationships among energy metabolism, endocrine controlling mechanism and immune system were introduced, and the recent progress on immunocompetence and life history trade-off was analyzed. The trade-off between survival and immunocompetence, as well as between reproduction and immunocompetence were discussed, and some developing perspectives and new problems in ecological immunology were proposed.