Meeting Abstract
Early-life challenges, such as suboptimal temperatures during development, can have profound effects on the phenotype. Recent evidence from several mammalian species suggests the gut microbiome may act as a mediator of developmental plasticity, including thermally-induced plasticity. Other recent research has shown that tree swallow (Tachycineta bicolor) nestlings developing in suboptimal temperatures have higher stress-induced corticosterone levels and greater thermogenic capacity via enlarged pectoral muscles. Here, we tested the hypothesis that cold-induced phenotypic plasticity is mediated by the gut microbiome. Nestlings were raised at either a cold (31°C) or neutral (35°C) temperature and given an antibiotic cocktail or a water control. Cold-reared birds mounted stronger corticosterone stress responses and higher stress-induced glucose levels than those reared at neutral temperatures. However, antibiotic treatment eliminated both of these effects. Neither temperature nor antibiotic treatment affected baseline corticosterone or glucose levels. Antibiotic treatment increased pectoral muscle mass in cold-reared birds; basal and cold-induced metabolic rates will be analyzed in the future to test whether treatment influenced thermogenic capacity. Thus far, our results demonstrate that gut microbiota may impact cold-induced phenotypic plasticity through alterations of stress responsiveness.
