Food availability in the nursery affects parental food allocation but not tadpole begging performance in a frog with facultative parental care

Abstract

Parents often have the opportunity to invest in offspring that offer different returns, with such variation arising from factors intrinsic to the offspring itself (e.g., body condition) or extrinsic (e.g., food availability in the environment). To identify the best targets for investment, parents may directly assess the environment or their offspring, but often also rely on offspring-generated signals when making investment decisions. We first used captive breeding pairs of the poison frog Ranitomeya imitator, a frog that facultatively feeds its young, to experimentally test how parents respond to variation in exogenous food availability in nurseries. We then used two experiments to test the prediction that, as is the case in many animals, the begging display of R. imitator tadpoles contains information about long- and short-term food intake. Parents rearing multiple tadpoles were more likely to feed and fed more to their tadpoles in control nurseries than to those in nurseries we supplemented. However, these control tadpoles completed metamorphosis at a smaller size. Tadpoles hand-reared on diets that drove differences in tadpole size did not differ in their begging at any point during development. Similarly, begging did not differ when tadpoles were food-deprived or fed. While parent R. imitator appear to invest strategically, begging seems unlikely to be parents’ source of information, at least about the size and development of their tadpoles. Parental favoritism and offspring begging have evolved in diverse lineages, and studies of animals that differ in their life-histories can continue to offer insights into how and why offspring-parent communication evolves.