Is corticosterone-mediated phenotype development adaptive? Maternal corticosterone treatment enhances survival in male lizards.
Hormones are an important interface between genome and environment, because of their ability to modify the phenotype. More particularly, glucocorticoids are known to affect both morphological, physiological and behavioral traits. Many studies suggest that prenatal stress (associated with an elevation of corticosterone) has deleterious effects on offspring, an altered physiology resulting in retardation of fetal growth and higher percentage of dead neonates. In this study, we investigate the consequences of an artificial increase of corticosterone in pregnant female Lacerta vivipara on two important fitness components: growth and survival. Do stressed females decrease or enhance offspring survival? In 2000 and 2001, we collected pregnant females from four populations of the Cevennes and kept them in the laboratory until parturition. We applied a corticosterone solution daily onto the backs of some females. A similar solution, but without corticosterone, was applied to the remaining females as a control. Immediately after birth, we measured juveniles' morphological characteristics and released them on the field. In September of the year of release and in May of the following year, we recaptured offspring to estimate growth and survival. The elevation of the corticosterone level in pregnant females L. vivipara had a profound impact on juvenile traits. The size, the body condition and the growth of juveniles were decreased by the corticosterone treatment. In contrast, in male juveniles, survival was higher for juveniles from corticosterone-treated females than from placebo females. Thus, corticosterone does not seem to have detrimental effects on offspring survival, suggesting that it may have an adaptive function.