Influence of Alternative Feeding Modes on Gene Expression and Microbiome Composition in Poison Frog Tadpoles

Abstract

Dendrobatid frogs have evolved a variety of unique behaviors related to parental care of tadpoles. However, few studies have investigated physiological adaptations and responses of tadpoles associated with different behaviors. The genus Ranitomeya provides a unique opportunity for comparative study as it includes two species that exhibit vastly different modes of tadpole feeding strategies: R. imitator tadpoles rely on infertile eggs provided by their parents, while R. variabilis tadpoles feed mainly on detritus. Despite these differences, tadpoles of both species can survive on alternative diets. We developed an experimental field study to compare responses to alternative feeding strategies and natural diets. To this end, we analyzed gut transcriptomes with accompanying microbiomes to investigate changes in bacterial composition and within the gut itself. Preliminary microbiome analyses revealed gut bacteria previously unknown from Ranitomeya poison frog tadpoles. Transcriptomic analyses uncovered 17 differentially expressed transcripts in R. imitator treatments, and 2,451 in R. variabilis. Critically, genes from a known group of symbiotic protists were highly expressed in egg-fed R. imitator tadpoles compared to those fed detritus. These results provide initial evidence for gut symbionts in these tadpoles, indicating the possibility that this symbiosis coevolved with egg-feeding in this species and facilitated the expansion of R. imitator into previously uninhabitable breeding pools.