Meeting Abstract

38.1  Tuesday, Jan. 5  Interactions between social stress and resource availability on tadpole growth, development and physiology CRESPI, Erica J*; WARNE, Robin W; Vassar College; Vassar College ercrespi@vassar.edu

Exposure to stressors during early development have been shown to have important impacts on physiological function, behavior, and fitness during later life stages in vertebrates, but the specific mechanisms that link these early experiences to the expression of later phenotypes are poorly understood. In this experiment, we explored the effects of chronic social stress and resource availability on growth, development, and variation in corticosterone (CORT) content in wood frog (Rana pipiens) tadpoles approach metamorphosis. We predicted that chronic social stress (and higher CORT levels) throughout development would alter growth and metamorphic timing, and these effects would be minimized when resource availability is high. To test these predictions, we marked early-staged tadpoles of same age to designate three size classes (i.e., social status) and raised replicate populations of tadpoles (n=51 tadpoles, 16-18/size class) in experimental mesocosms of both high and low food availability (n=6/food treatment). We then measured body length, mass, femur length and CORT content as tadpoles approached metamorphosis (Gosner stage 38-39). We found that high-status tadpoles metamorphosed before the other classes, but food availability had no effect on developmental timing. By contrast, reduced food availability caused tadpoles of lower social status to develop more slowly, which allowed them to metamorphose at a larger body size than high status tadpoles. Their hindlimbs were significantly smaller, however, which may suggest an allocation trade-off that could affect long-term fitness. Assessment of CORT content of these tadpoles at metamorphosis and as juveniles will allow us to determine both proximate and long-term impacts of social status and nutrition on neuroendocrine stress axis function.