Boosting Lizard Immunity Against Warmer Weather with Gut Health

Greg Howard
24th February, 2024

Boosting Lizard Immunity Against Warmer Weather with Gut Health

Graphical Abstract from study.

Image adapted from: Yang et al. / CC BY (Source)
Climate change is causing significant shifts in global temperatures, posing a threat to the survival of many species. Ectothermic animals – those that rely on external sources for body heat, like reptiles – are particularly vulnerable, as their physiological processes are directly influenced by environmental temperature. A key question is how these animals will adapt, and a growing body of research suggests that the microorganisms living within their guts – their gut microbiota – may play a crucial role. Researchers at the Chinese Academy of Sciences[1] investigated how long-term warming affects the gut microbiota of a desert lizard, Eremias multiocellata, and its impact on the lizard’s immune system. Previous studies have indicated that warming can reduce the diversity of gut microbes, potentially harming the host’s health[2]. However, this research took a longer-term perspective, tracking changes over almost two and a half years. The study involved exposing lizards to warmer temperatures in a semi-natural environment and then monitoring changes in their gut microbiota composition, immune function, and overall health. Surprisingly, the researchers found that while warming initially decreased gut microbial diversity after two months, diversity actually increased at 13 and 27 months. This suggests that the gut microbiota isn’t simply degraded by warming, but undergoes a more complex, dynamic shift over time. Alongside these changes in microbial diversity, the study revealed significant improvements in the lizards’ immune responses. Specifically, the lizards exposed to warming exhibited increased antibacterial activity in their blood serum – the liquid part of blood – and higher expression of genes related to immunity in their intestines. This indicates a strengthened ability to fight off infections. Furthermore, the concentration of short-chain fatty acids, compounds produced by gut bacteria that are vital for gut health and immune function, also increased. These fatty acids help maintain the integrity of the intestinal barrier and further boost immunity. To confirm that the changes in gut microbiota were directly responsible for the improved immune function, the researchers performed fecal microbiota transplant experiments. This involved transferring gut microbes from warmed lizards to lizards that hadn’t been exposed to warming. The recipient lizards showed enhanced antibacterial activity and immune responses, demonstrating a causal link between the altered gut microbiota and improved immunity. The researchers identified a specific bacterium, Bacteroides fragilis, as a key player in this process. They found that the abundance of Bacteroides increased in the warmed lizards, and that this bacterium regulates the expression of a gene called IFN-β, which is crucial for triggering an immune response. This suggests that warming promotes the growth of Bacteroides, which then enhances the lizard’s ability to defend against pathogens. These findings build upon earlier research highlighting the importance of symbiotic relationships – interactions between different species – in helping animals cope with environmental change[3][4]. The study demonstrates that beneficial microbes can not only provide essential resources to their hosts but also protect them from disease[5]. It also aligns with observations that climate change is driving widespread ecological and evolutionary changes in species, including shifts in their microbial communities[3]. The study’s results challenge the initial assumption that warming always negatively impacts gut microbial diversity and host health. It highlights the importance of considering long-term effects and the potential for adaptation through host-microbe interactions. The research suggests that gut microbiota can act as a buffer, helping ectothermic animals like desert lizards cope with the challenges of a warming climate by enhancing their immune defenses.

WildlifeHealthEcology

References

Main Study

1) Gut microbiota modulation enhances the immune capacity of lizards under climate warming.

Published 22nd February, 2024

https://doi.org/10.1186/s40168-023-01736-2

Related Studies

2) Divergent impacts of warming weather on wildlife disease risk across climates.

https://doi.org/10.1126/science.abb1702

3) The broad footprint of climate change from genes to biomes to people.

Journal: Science (New York, N.Y.), Issue: Vol 354, Issue 6313, Nov 2016

4) Symbiosis and host responses to heating.

https://doi.org/10.1016/j.tree.2022.03.011

5) Symbiont-mediated protection in insect hosts.

https://doi.org/10.1016/j.tim.2009.05.005


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