Climate change threatens wild meerkats in the South African Kalahari. Biologists from Ulm University were able to document changes in the animals' intestinal microbiome using faecal samples. The result: Over the past 20 years, disease-associated Bacteroidia have overgrown the microbiome at the expense of health-promoting lactic acid bacteria. This in turn seems to make the meerkats more susceptible to tuberculosis and a shortened life span. The study has been published in the journal Global Change Biology.
The average peak temperature in the South African Kalahari has increased by more than two degrees over the past 20 years, which is five times more than the global average. During the same period, the faecal microbiota of the Kalahari meerkats (Suricata suricatta) has seen a significant increase in mostly disease-associated Bacteroidia – at the same time, beneficial lactic acid bacteria have diminished. 'These shifts did not only occur within currently alive individuals but were compounded over generations,' describe the first authors of the publication, Dr. Alice Risely and Dr. Nadine Müller-Klein from the Institute of Evolutionary Ecology and Conservation Genomics at Ulm University.
Greater abundance of Bacteroidia is furthermore associated with the spread of tuberculosis in the meerkat population. Phases of dry, hot weather, poor constitution and the occurrence of tuberculosis are factors directly linked to an up to ten times lower survival rate of small mammals. The simultaneous loss of lactic acid-producing bacteria, which are important for the health of host organisms, has also been shown to contribute to increased mortality. The biologists thus answered a hitherto unresolved yet essential question: Do changes in climate affect the intestinal microbiome and thus the fitness of their wild animal hosts in the longer term?
The researchers from Ulm analysed 1.141 faecal samples from 235 individual meerkats, which had been collected by the Kalahari Meerkat Project under the direction of Professor Tim Clutton-Brock (University of Cambridge, UK) and Professor Marta Manser (University of Zurich, Switzerland) since 1993 in the Kuruman River Reserve in northern South Africa. The biologists travelled from Ulm to the Kalahari to observe the sampling on site, give talks and discuss further projects with their collaboration partners. During their last stay in 2023, the scientists also succeeded in picking up the tracks of a group of meerkats with tuberculosis whose trace had been lost for months. Back in the research laboratory at Ulm University, they then extracted the bacterial DNA from the faecal samples and identified a specific gene in order to distinguish the various bacteria.
The microbiota, or the community of bacteria in the intestine, is of central importance for the metabolism and immunity of the host mammal. It regulates the balance of many central physiological processes in the organism. Disturbances of the microbial community over a longer period can have serious consequences and lead to so-called dysbiosis, which is often associated with the loss of useful bacteria and an increase in potentially pathogenic bacteria. A variety of stressors can cause such disturbances, including, among other things, human-caused alterations to the habitat coupled with climate-induced changes in the natural diet, changing social environment, psychological and physical stressors, environmental toxins such as fertilisers or weed killers, medicines, diseases, etc. In this long-term study, the researchers used a statistical model to identify a connection between temperature changes and the composition of the intestinal bacterial community. 'The fact that climate change can also disturb intestinal bacteria was unknown thus far,' summarises Dr. Dominik Schmid, also a member of the research group.
Professor Simone Sommer, head of the Institute of Evolutionary Ecology and Conservation Genomics at Ulm University, contextualises the observed changes in the meerkat microbiota with regard to global warming: 'Long-term studies on the microbial intestinal community of wild animal species are extremely rare. Often, investigations about the consequences of temperature changes or susceptibility to disease have to take place in the form of experiments or shorter-term observations, which then serve as the basis for hypotheses. In order to understand whether the suspected effects are biologically significant, however, these hypotheses need to be verified based on long-term data and under natural conditions, which we had the opportunity to do for the first time here.'
This study is the first to document the effects of climate change and disease dynamics on the composition of the gut microbiome in a region of the world where global warming unfolds five times faster than in the rest of the world.
Risely, A., Müller-Klein, N., Schmid, D. W., Wilhelm, K., Clutton-Brock, T. H., Manser, M. B., & Sommer, S. (2023). Climate change drives loss of bacterial gut mutualists at the expense of host survival in wild meerkats. Global Change Biology, 00, 1–13
Text and media contact: Daniela Stang