Meeting Abstract

68.3  Sunday, Jan. 6  Fever and sickness behavior vary among Peromyscus mice MARTIN, LB*; WEIL, ZM; NELSON, RJ; University of South Florida; Ohio State University; Ohio State University lmartin@cas.usf.edu

Fever and sickness behavior are immune defenses that most organisms engage to control bacterial and viral infections. Although generally beneficial, these defenses can be energetically expensive, which may lead to variation within and among species. Here, we asked whether fever and sickness behavior differ among five species of mice in the genus, Peromyscus. This comparison was motivated by our previous discovery of extensive, but systematic, immunological variation among some of these same species. Some species were adept at controlling gram-negative bacteria, whereas others were proficient at generating antibodies; no species was strongly capable of both. Such discrete variation suggested a continuum of immune defense strategies. We therefore predicted that variation in fever and sickness behavior would mirror variation in bacterial killing capacity, as these defenses are mediated by some of the same molecular pathways. To test this hypothesis, we characterized responses to lipopolysaccharide (LPS), a component of gram-negative bacteria that activates fever without causing infection. Altogether species that showed little sickness behavior post-LPS engaged fever; species that engaged sickness behavior, however, either did not adjust body temperature or became hypothermic post-LPS. As predicted, species that were adept at killing bacteria mounted the largest fevers; species that were not as proficient at killing bacteria did not engage fever. These results further indicate a continuum of immunological strategies among Peromyscus species. We propose a few possible reasons for why species occupy specific points along the immune continuum; life history orientation appears the most viable alternative at present.