Poison frog tadpoles seek parental transportation to escape their cannibalistic siblings

Abstract

Parental care is a limited resource which in many species is acquired by the offspring through begging behaviours and often causes competition between siblings. The Neotropical poison frog Ranitomeya variabilis provides a very specific form of parental care: because its tadpoles are cannibalistic males usually separate them from their siblings after hatching by transporting them singly to small water bodies. However, in some cases parents do not transport their tadpoles but let them all hatch into the same pool. Here, we investigate if abandoned tadpoles of R. variabilis actively seek parental care in form of transportation. We conducted experiments where tadpoles of the same clutch were presented with con-and heterospecific frogs, and both moving and non-moving frog models. Our results revealed that abandoned tadpoles actively approached all frogs and sometimes even climbed onto their backs. We suggest that this tadpole behaviour may function to allow tadpoles to escape sibling competition and cannibalism. Being the first (and possibly the only one) to leave the shared pool should give a tadpole a high survival advantage over its brood-mates. We further found that tadpoles did not approach artificial models, suggesting that these where either not natural enough or that tadpoles do not recognize frogs by visual or tactile cues but might use chemical or multiple stimuli. The latter is also the case in related egg-feeding species where tadpoles beg for food. We therefore discuss our results in relation to potential begging behaviours, as well as fixed action patterns and parent-offspring conflict, being potential questions opening up for future examinations regarding our findings.

The evolution of parental care diversity in amphibians

“…By investigating diversity of care in a single taxon, our study also reveals that behaviours, such as tadpole transport, are lost at relatively low rates. Albeit apparently simple, transport requires good parental spatial memory of suitable pools with low predation risk in which to release the offspring 46,47 , and involves some level of parent-offspring conflict and sibling competition when parents can only take one or few offspring at a time 47–49 . Together, these characteristics may explain why transport exhibits moderate rates of evolution.…”

Developments in Amphibian Parental Care Research: History, Present Advances, and Future Perspectives

“…It is increasingly evident that amphibians are an excellent system to address timely and relevant questions about the evolution of reproductive strategies, including parental care (i.e., Kupfer et al 2006;Brown et al 2010;Poo and Bickford 2013;Reinhard et al 2013;Stynoski et al 2014b;Vargas-Salinas et al 2014;Lehtinen et al 2014;Rojas 2014;Bravo-Valencia and Delia 2016;Yoshioka et al 2016;Delia et al 2017;Ringler et al 2017;Schulte and Mayer 2017;Stynoski et al 2018). The advent of new technologies has broadened the range of questions that can be addressed concerning the molecular and physiological underpinnings of parental behaviors (Roland and O'Connell 2015;Fischer et al 2019).…”

Hierarchical decision‐making balances current and future reproductive success

“…In many anuran species, larval density is found to negatively impact larval fitness due to increased competition for limited resources such as food and space, which may increase time to, and decrease size at metamorphosis, ultimately reduce larval survival (Relyea & Hoverman, ; van Allen, Briggs, McCoy, & Vonesh, ). Cannibalism on tadpoles or eggs is also common in many dendrobatid tadpoles (Caldwell & de Araújo, ; Schulte & Mayer, ; Summers & Symula, ), resulting in strong avoidance of already occupied water bodies in these species (Schulte & Lötters, ). As A. femoralis tadpoles do not prey on each other (Weygoldt, , obs.…”