Meeting Abstract
The environment that a mother experiences while carrying young can have dramatic effects on the phenotype and fitness of her offspring. One mechanism that can cause such effects is the transfer of maternal steroid hormones to offspring either through the placenta or deposition into egg yolk. While the effects of stressors on transfer of glucocorticoids (GCs) to egg yolk have been well studied, we know less about how more subtle increases in maternal GCs may impact egg hormone levels. We examined how moderate increases in maternal GCs due to exercise training affect levels of corticosterone in egg yolk. In mammals, maternal exercise typically has positive influences on offspring physiology, but there are mixed results among studies, and we know very little about how maternal exercise affects non-mammals or oviparous species. We manipulated diet and allocation of resources to performance, via exercise training, to examine how steroid hormones change in mothers, as well as how hormones were deposited in egg yolk. Captive green anole lizards were assigned to one of four treatment combinations across two factors (diet restricted or not and endurance trained on a treadmill or not) over the course of nine weeks. Previous work showed that endurance training resulted in dramatic performance enhancement but at a cost to immune function and reproductive output. Training resulted in increased female corticosterone levels, but diet restriction resulted in reduced testosterone levels. Here we sought to determine whether these effects translated into correlated differences in egg yolk steroid profiles. Matching maternal activity (i.e., exercise) with circulating GC levels makes energetic sense, and matching offspring GC exposure in ova may be a mechanism to match offspring activity to an environment that requires increased activity.
