Meeting Abstract
An organism’s environment during development can have effects on phenotype that carry over into adulthood. Developmental stressors are thought to have a negative impact on physiological functions and fitness. However, recent work suggests that a mild developmental stressor can have beneficial effects via preparing the organism to better withstand negative impacts when exposed to high levels of the stressor later in life. We hypothesized that acquired stress tolerance decreases the negative effects of heat stress on fitness-related traits. To test this we exposed zebra finches (Taeniopygia guttata) to a prolonged mild heat stress (38° C) as juveniles for 28 days with the prediction that the birds will gain an acquired thermotolerance which will continue into adulthood. As adults the birds were then exposed to a high heat stressor (42° C) for 3 consecutive days and we examined the effects of heat stress on immune function and reproductive performance. More specifically, we measured wound healing rate as a proxy for an overall immune function. To do this, healing rate of a skin excision approximately 3.0 mm in diameter was measured. We predict that birds subjected to the mild heat treatment as juveniles and the high heat as adults will have a comparable rate of wound healing to those of the control-control group, and those that were exposed to the high heat treatment as adults but not conditioned as juveniles are expected to have the slowest wound healing rate. We also tested whether conditioned individuals had higher reproductive performance compared to controls. Following wound healing completion, females were paired with non-experimental males and clutch size and egg mass were measured. We predict that heat conditioned females have a higher clutch size or egg mass compared to controls.
