Tadpole Begging Behavior And Parent-Offspring Interactions In The Mimic Poison Frog

Abstract

Studies on offspring begging behavior have focused on whether the behavior communicates offspring need and guides parental food provisioning in the context of honest signaling theory. However, despite the plethora of empirical work on this issue applied to avian systems, begging occurs in the absence of direct sibling interactions in some species, and so may not be selected for solely in the context of intrabrood dynamics, as traditionally hypothesized. Here we broaden the taxonomic scope of investigations into the phenomenon by studying begging behavior in the Peruvian mimic poison frog (Ranitomeya imitator). This system presents several advantages, including individually housed and cared for offspring (eliminating the confounding influence of sibling competition on begging behavior). We specifically investigated in R. imitator, a) whether begging is an honest signal of need, or a signal of quality (or neither), b) if begging is costly, and c) if food-provisioning by parents depends on offspring need. First, under manipulation of long-term diet, cumulative nutritional deficits significantly affected begging behavior, with food-limited tadpoles begging increasingly more over the course of development. In a second experiment, tadpoles induced to beg suffered a cost of taking longer to reach developmental marker stages. Compared to the control group, begging tadpoles also had marginally lower growth rates. Finally, in an experiment testing parental response to tadpoles experiencing different levels of nutrition, parents were more likely to feed the tadpole that did not receive any supplemental food over its food-supplemented sibling. Congruently, the non-supplemented tadpoles were on average fed relatively more frequently. Together, the findings from this study suggest that in the mimic poison frog, offspring begging behavior acts as an honest signal of offspring need and influences how provisioning parents differentially allocate food among their offspring.