Differential Temporal Shifts in Skin Bacteria on Wild and Captive Toads

Skin bacteria on amphibian hosts play an important role in host health, but those communities are also constantly shifting based on environmental and host-related feedback. On some hosts, stability of skin communities depends on relatively abundant taxa, with less abundant taxa more readily entering and exiting the system. Cane toads (Rhinella marina) have invaded widespread, diverse tropical ecosystems, with varying ecology, physiology, and behaviour in different environments. In this study, we described temporal patterns of skin bacterial communities on cane toads at a site in northern Australia through the wet and dry seasons over two years. Toads in the wild population were paired with a captive-held population, housed in a semi-natural environment, to detect effects of time and season on wild toads, explore bacterial transience and volatility in skin taxa, and determine the extent to which skin communities on captive toads represent those on the wild population. We found community differences by captivity status, sampling timepoint, and season, with increased richness in the wet season on wild toads. Bacterial communities also became more similar among individuals (lower dispersion) in the wet season. Captive toads harboured more stable communities over time, likely owing to the reduced bacterial reservoirs experienced while in captivity. We propose that cane toads, with varied movement patterns among their diverse invaded habitats, provide an interesting direction for future work understanding the influences of habitat and movement on skin microbes, and the flexibility of microbial symbiotic interactions in invasive hosts.