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.

Reliably capturing transient animal behavior in the field and laboratory remains a logistical and financial challenge, especially for small ectotherms. Here, we present a camera system that is affordable, accessible, and suitable to monitor small, cold-blooded animals historically overlooked by commercial camera traps, such as small amphibians. The system is weather-resistant, can operate offline or online, and allows collection of time-sensitive behavioral data in laboratory and field conditions with continuous data storage for up to four weeks. The lightweight camera can also utilize phone notifications over Wi-Fi so that observers can be alerted when animals enter a space of interest, enabling sample collection at proper time periods. We present our findings, both technological and scientific, in an effort to elevate tools that enable researchers to maximize use of their research budgets. We discuss the relative affordability of our system for researchers in South America, which is home to the largest population of ectotherm diversity.

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Social experience early in life appears to be necessary for the development of species-typical behavior in animals ranging from insects to primates. Isolation during critical periods of maturation has been shown to impact behavior, gene expression, and brain development in vertebrate and invertebrate clades, yet remarkable resilience to social deprivation, senescence, and loss of sensory input have been demonstrated in some ant species. We reared workers of Camponotus floridanus under conditions of social isolation for increasing time periods up to 45 days and evaluated their behavioral performance, quantified brain development and biogenic amine levels, and compared results of isolated workers with control workers that had natural social contact during development. We found that brood care and foraging performance by isolated workers were unaffected by a lack of social contact. Antennal lobe volume loss occurred in ants experiencing longer isolation periods, while the size of the mushroom bodies, which function in higher-order sensory processing, increased over time after eclosion and were not different from mature controls. Titers of the neuromodulators serotonin, dopamine, and octopamine remained stable in isolated workers. Our results indicate that workers of C. floridanus are largely robust to the deprivation of social contact early in life.