Beyond ecology: the importance of gut motility in predicting the responses of species to climate change.

This Review explores the impact of environmental factors, with temperature as a starting point, on gut motility and digestive function in non-mammalian vertebrates, with a focus on species that are likely to be affected by climate change. Understanding gut physiology, particularly motility, is crucial in allowing us to predict how animals will respond to changing environmental conditions, as it plays a key role in nutrient absorption, immune defence and overall health. Rising temperatures and heatwaves pose significant challenges, especially for ectothermic species, the gut functions of which may be compromised under conditions outside their thermal tolerance. Here, we provide examples of how temperature-induced changes in gut motility affect gut transit time and digestive efficiency, and discuss their effects on the balance of energetic cost and gain. Although higher temperatures generally accelerate motility, further research is needed to assess how these changes impact digestion across species and under fluctuating environmental conditions. This Review emphasizes the need for integrated studies on motility patterns, digestive efficiency and energetic costs - along with the neural and cellular mechanisms controlling motility - to better predict the resilience of species in a warming world.