Meeting Abstract
Exposure to stress during an organism’s development or in previous generations can have important lasting effects on physiology and immune function. Prolonged exposure to stress-relevant hormones (e.g. corticosterone, CORT) can have fitness costs such as suppressed immune function. We may thus expect that the physiological stress response, and its effect on other parameters, may be altered to reduce associated costs in high stress populations. We investigated the effects of developmental stress and cross-generational exposure to stress on the physiological stress response and immune function. We collected gravid lizards (Sceloporus undulatus) from populations with long histories of invasion by predatory fire ants (Solenopsis invicta) and from uninvaded sites. Resulting hatchings were exposed weekly to stress (fire ant attack or topical CORT) until maturity, and blood samples were obtained several months later. Developmental stress did not directly affect baseline or handling-induced levels of CORT. Offspring from high stress (fire ant invaded) populations, however, had a more robust CORT response to handling than did those from low stress sites. Among lizards treated with CORT during development, offspring from high-stress populations had higher hemagglutination scores (more robust immune response) than did those from low stress sites. No differences in bacterial killing ability were observed. These results suggest that selection may favor elevated stress responses at these high-stress sites and up-regulated immune function in response to developmental stress. At high-stress sites where immune function is frequently activated (e.g. by fire ant attacks), it may be adaptive to up-regulate immune function in response to developmental stress.
