phaidra.vetmeduni.ac.at o:1790 DOI 10.1038/s41598-022-06359-5 Glucocorticoids coordinate changes in gut microbiome composition in wild North American red squirrels Abstract: The gut microbiome impacts host health and fitness, in part through the diversification of gut metabolic function and pathogen protection. Elevations in glucocorticoids (GCs) appear to reduce gut microbiome diversity in experimental studies, suggesting that a loss of microbial diversity may be a negative consequence of increased GCs. However, given that ecological factors like food availability and population density may independently influence both GCs and microbial diversity, understanding how these factors structure the GC-microbiome relationship is crucial to interpreting its significance in wild populations. Here, we used an ecological framework to investigate the relationship between GCs and gut microbiome diversity in wild North American red squirrels (Tamiasciurus hudsonicus). As expected, higher GCs predicted lower gut microbiome diversity and an increase in metabolic taxa. Surprisingly, but in line with prior empirical studies on wild animals, gastrointestinal pathogens decreased as GCs increased. Both dietary heterogeneity and an upcoming food pulse exhibited direct effects on gut microbiome diversity, whereas conspecific density and reproductive activity impacted diversity indirectly via changes in host GCs. Our results provide evidence of a gut-brain axis in wild red squirrels and highlight the importance of situating the GC-gut microbiome relationship within an ecological framework. eng Population-Growth; Brain Axis; Metabolism; Responses; Behavior; Stress; Sex; Corticosterone; Reproduction; Evolution 2023-07-03T13:35:54.149Z LOMv1.0 Author BEGIN:VCARD VERSION:3.0 N:Petrullo;Lauren; FN:Lauren Petrullo END:VCARD BEGIN:VCARD VERSION:3.0 N:Dantzer;Ben; FN:Ben Dantzer END:VCARD BEGIN:VCARD VERSION:3.0 N:McAdam;Andrew G.; FN:Andrew G. McAdam END:VCARD BEGIN:VCARD VERSION:3.0 N:Boutin;Stan; FN:Stan Boutin END:VCARD BEGIN:VCARD VERSION:3.0 N:Palme;Rupert; FN:Rupert Palme X-ORCID:https://orcid.org/0000-0001-9466-3662 END:VCARD BEGIN:VCARD VERSION:3.0 N:Boonstra;Rudy; FN:Rudy Boonstra END:VCARD BEGIN:VCARD VERSION:3.0 N:Ren;Tiantian; FN:Tiantian Ren END:VCARD BEGIN:VCARD VERSION:3.0 N:Wu;Martin; FN:Martin Wu END:VCARD https://w3id.org/kim/hcrt/scheme https://w3id.org/kim/hcrt/text Textdokument Text LOMv1.0 yes https://creativecommons.org/licenses/by/4.0 application/pdf 1644224 https://phaidra.vetmeduni.ac.at/o:1790 https://phaidra.vetmeduni.ac.at/api/object/o:1790/thumbnail LOMv1.0 discipline