Meeting Abstract

P1.149  Sunday, Jan. 4  Hormonal Regulation and the Evolution of Novel Feeding Strategies LEDON-RETTIG, C.C.*; CRESPI, E.J.; PFENNIG, D.W.; Univ. of North Carolina, Chapel Hill; Vassar College; Univ. of North Carolina, Chapel Hill ledonret@email.unc.edu

Feeding strategies are diverse, even among closely related taxa, but little is known about how organisms shift to a new diet. Adopting a novel diet is likely stressful for organisms, eliciting hormonal changes that can influence their development and fitness. However, it is unknown whether consuming a novel diet elevates the production of corticosterone (CORT, the principle vertebrate stress hormone). The drastically different larval feeding habits of closely related spadefoot toads (genera Scaphiopus and Spea) are ideal for evaluating diet-induced changes in CORT. Scaphiopus larvae, like most anurans, feed on detritus and plankton. In contrast, some Spea larvae have also evolved the ability to specialize on macroinvertebrate prey, such as fairy shrimp. Because Scaphiopus is Spea’s closest sister group, and because they share the same feeding strategy as most other anuran larvae, Scaphiopus is likely similar to ancestral Spea in its feeding strategy as well as its diet-induced hormonal responses. Thus, by using Scaphiopus as a substitute for ancestral Spea, we can infer what hormonal changes must have evolved in order for Spea to make the transition to its modern diet of shrimp. Using radioimmunoassay we quantified concentrations of CORT in both genera, when both were either fed the derived (shrimp) or ancestral (detritus) diet. The results from this research will serve as a springboard for investigations of downstream regulators of hormonal action, such as nuclear hormone receptor expression.