Gut microbiota developmental thermal plasticity tree swallow

As the global climate changes, many organisms are increasingly exposed to extreme temperatures. Plastic responses to developmental temperature could enable organisms to better match their environments, including by altering future thermoregulatory capacity. Little is known about when and how this occurs in most taxa including birds, which experience a particularly wide range of temperatures throughout development. Here we show evidence of microbially-mediated thermal plasticity in nestlings from a free-living population of tree swallows experimentally reared at suboptimally low temperatures. These results suggest a novel pathway through which birds could respond quickly to changing temperatures. Ultimately, this could mitigate or exacerbate the costs of shifting thermal environments.