Meeting Abstract
Urban environments are amongst the fastest growing and most widely distributed ecosystems in the world, and organisms colonizing these environments are subject to a wide suite of novel stressors and selective pressures. While urban linked ecological changes have been well described, our understanding of the physiological mechanisms by which wildlife respond to these challenges is lacking. An organism’s response to stressors is mediated by the hypothalamic-pituitary-adrenal (HPA) axis, a core component of the endocrine system and a key physiological mechanism connecting an organism to its environment. In addition, the HPA axis exists in an intimate bidirectional relationship with the microbiome. Using wild grey squirrels, we seek to understand the influence of the urban environment on stress physiology and the microbiome by characterizing patterns in glucocorticoid and microbiome profiles among urban and ex-urban environments. To explore the effect of urbanization on the HPA axis, we examined multiple measures of stress physiology differing in temporal resolution (chronic: hair cortisol; integrated: fecal glucocorticoid metabolites; acute: dexamethasone-adrenocorticotrophic hormone challenges). Subsequently, to probe the influence of HPA axis activity on microbiome structure and function, we performed a large-scale field experiment to manipulate glucocorticoids and assess corresponding changes in microbiome profiles. Unfurling the relationships between urbanization, stress physiology and microbiome structure in wildlife provide an opportunity to understand how wildlife cope with, adapt to, or even exploit novel environments.
