Experimental depletion of gut microbiota diversity reduces host thermal tolerance and fitness under heat stress in a vertebrate ectotherm

Abstract

Predicting the responses of ectotherms to climate change is a global conservation priority which requires identifying factors that influence how animals respond physiologically to changing temperature. Host-associated microbial communities impact animal physiology and have been shown to influence host thermal tolerance in invertebrate systems. However, the role of commensal microbiota in thermal tolerance of ectothermic vertebrates is unknown. Here we show that experimentally depleting the diversity of the tadpole gut microbiome through environmental water sterilization reduces the host's acute thermal tolerance to both heat and cold, alters the thermal sensitivity of locomotor performance, and reduces animal survival under acute heat stress. We show that these tadpoles have reduced activities of mitochondrial enzymes and altered metabolic rates compared to tadpoles colonized with a diverse microbiota, which could underlie differences in thermal phenotypes. Our results demonstrate, for the first time, a link between the gut microbiome of an ectothermic vertebrate and the host's thermal tolerance, performance, and fitness, thus highlighting the importance of considering host-associated microbial communities when predicting species' responses to climate change.

Effects of Microhabitat Temperature Variations on the Gut Microbiotas of Free-Living Hibernating Animals

“…Heat acclimation experiments in both ectotherm and endotherm hosts have shown that variations in environmental temperature significantly affect the gut microbial community ( 9 , 24 – 26 ). In this study, we used high-throughput 16S rRNA gene sequencing to investigate the impact of microhabitat temperature variations on gut microbial composition and diversity in R. pusillus .…”

Growing and maintaining a network for early career researchers through the Animal Microbiome Research Group

“…Dr. Kevin Kohl showed that microbial communities contributed to host thermal tolerance in tadpoles subjected to temperature increase. 7 In wild Anolis lizards, short-term climate warming does not have a significant effect on the gut microbiome whereas sustained drought does, as explained in Claire E. Williams's poster (University of Nevada, USA). In addition to climate change, pollutants and radiation exposure can also impact wild animals gut microbiome as illustrated by Dr. Diana Lafferty (Northern Michigan University, USA) working on wild boars in the Fukushima difficult-to-return zone, and Sameli Piirto (University of Jyväskylä, Finland) whose PhD project will investigate the effects of radionuclides exposure on great tits in Chernobyl (Ukraine).…”

“…External factors also shape an individual's microbiome with consequences on host fitness, especially in the face of anthropogenic perturbations. Dr. Kevin Kohl showed that microbial communities contributed to host thermal tolerance in tadpoles subjected to temperature increase 7 . In wild Anolis lizards, short‐term climate warming does not have a significant effect on the gut microbiome whereas sustained drought does, as explained in Claire E. Williams's poster (University of Nevada, USA).…”