Physiological state matching in a pair bonded poison frog

Abstract

Empathy is critical to individual and social wellbeing in humans. More than a century ago, Charles Darwin hypothesized that the empathy-like phenotype is a phylogenetically widespread phenomenon. This idea remains contentious, partly due to few investigations among non-mammalian vertebrates. We provide evidence for Darwin's hypothesis by discovering key empathetic features, emotional contagion and ingroup bias, in pair bonding Ranitomeya imitator (Mimetic) poison frogs. We found that the corticosterone level of males appears to positively correlate with female partners across various conditions, including cohabitation and during experimental manipulation. This response is selective towards female partners relative to familiarized female non-partners and is irrespective of partnership longevity or lifetime reproductive output. However, hormonal state matching is not reflected behaviorally, indicating that behavioral state matching can be an unreliable proxy for emotional contagion. These results constitute the first evidence for emotional contagion in an amphibian. Together with findings in other taxa, they suggest empathy is evolutionarily widespread among social vertebrates.

Why not both? A case study measuring cortisol and corticosterone in poison frogs

“…Our goal for this study was to investigate which glucocorticoid is the primary hormone of the HPA axis in Dendrobatid poison frogs. Both cortisol (Fischer and O'Connell, 2020) and corticosterone (Nowicki et al, 2022) have been measured in poison frogs, albeit in different species and sample types (plasma from Dendrobates tinctorius and water from Ranitomeya imitator, respectively). We tested interspecific variation in the relationship between cortisol and corticosterone and focused on the response of both glucocorticoids to a physiological stressor in one species.…”

“…We used non-invasive water-borne hormone sampling to allow for repeated measures from the same individuals (Baugh et al, 2018; Gabor et al, 2013; Rodríguez et al, 2022). Both cortisol (Fischer and O’Connell, 2020) and corticosterone (Nowicki et al, 2022) have been previously measured in poison frogs, albeit in different species and sample types (plasma from Dendrobates tinctorius and water from Ranitomeya imitator , respectively).…”