Meeting Abstract
48.3 Thursday, Jan. 6 Chytridiomycosis is metabolically costly and induces sickness behavior and immune effects that are linked to increased corticosterone secretion. PETERSON, J.D.*; STEFFEN, J.E.; APPEL, A.G.; ROLLINS-SMITH, L.A.; MENDONCA, M.T.; Auburn Univ. & Troy Univ.; Penn State Erie; Auburn Univ.; Vanderbilt Univ.; Auburn Univ. peterj1@auburn.edu
Chytridiomycosis, a disease caused by the amphibian chytrid fungus (Batrachochytrium dendrobatidis [Bd]), has contributed to amphibian population declines the world over, but little is known about how this disease influences behavior and physiology. Recent research suggests that Bd infection causes hyponatremia and cardiac failure. However, individuals with chytridiomycosis also exhibit behavioral and immunological effects that seem unrelated to changes in ion homeostasis. Amphibians with chytridiomycosis display sickness behavior (e.g. anorexia and lethargy) and altered leukocyte abundances. Since sickness behavior and lymphocyte abundances are both partially regulated by stress hormones, we documented effects of disease status (symptomatic vs. asymptomatic) on Bd intensity, food intake, plasma corticosterone (a stress hormone), and lymphocyte abundances during a laboratory outbreak of chytridiomycosis in Litoria caerulea. Additionally, since sickness behavior is assumed by evolutionary ecologists to be advantageous, conserving energy to cope with infection, we documented effects of disease on metabolic rate. Compared to asymptomatic frogs, frogs symptomatic for chytridiomycosis displayed significant decreases in food intake and lymphocyte abundances and significant increases in Bd intensity, plasma corticosterone, and metabolic rate. These changes occurred at similar Bd intensities, suggesting that they are temporally associated with disease progression and likely occur several weeks before death. The potential importance of these findings to our understanding of stress physiology, sickness behavior, life-history trade-offs, and the mechanistic progression and virulence of chytridiomycosis will be discussed.
