Climate change poses many challenges for wildlife. Among other things, the rising temperatures are changing their intestinal microbiome, as researchers have now discovered using meerkats. According to this, over the past 20 years, pathogenic types of bacteria have increasingly accumulated in the intestines of small mammals, while the number of health-promoting lactic acid bacteria has decreased. As a result, the meerkats get sick more often and die earlier than they did a few decades ago.
The composition of the bacterial community in our gut plays an important role in our immune system and our susceptibility to infections. A high proportion of "good" bacteria such as lactic acid bacteria strengthens our body's immune response and thus protects us from diseases. However, if the "bad" bacteria get the upper hand, this in turn makes us more susceptible to dangerous infections.
Collecting droppings in the Kalahari
The bacterial communities in the gut also play such a role in wild animals. It is therefore important to know which factors can unbalance your gut microbiome and sometimes lead to premature death. Biologists have long suspected climate change as a harmful influence. But Alice Risely from the University of Ulm and her colleagues have now checked this connection directly for the first time, using meerkats in the Kalahari. These socially living small mammals are particularly well suited for this because they are feeling the effects of climate change with all severity. Temperatures in the South African desert have risen five times faster than the global average over the past 20 years. On hot days it is sometimes two degrees warmer here than it was just a few decades ago.
At the same time, there are more and more cases of tuberculosis among the meerkats living there, which also lead to the death of the animals. This could be a sign that rising temperatures have altered the meerkats' gut microbiome, making them more susceptible to dangerous infections. To check this, Risely and her team analyzed the intestinal microbiome of a total of 235 animals. They were able to do this using 1,141 fecal samples collected by project partners on site between 1997 and 2019. Using the bacteria contained in the faeces, the researchers were able to check how the microbial balance in one and the same animal had changed over time, but how its composition had developed from generation to generation.
Climate change is causing meerkats to die earlier
The result: Over the past 20 years, the microbiome of Kalahari meerkats has been enriched with pathogenic microbes from the Bacteroidia group, as Risely and her colleagues report. At the same time, the number of health-promoting lactic acid bacteria has decreased. "These shifts did not only occur within currently living individuals, but were amplified over generations," explains the Ulm researcher. The fact that the number of bad bacteria in the gut is constantly increasing while the number of good bacteria is declining could also explain why more and more meerkats contract tuberculosis and die prematurely. Your immune system is simply no longer strong enough to successfully fend off the pathogen.
Risely and her team attribute the fact that these shifts in the intestinal microbiome take place at all to the influences of climate change. They were able to demonstrate a clear statistical connection between dry, hot weather phases and the increase in pathogenic bacteria. "The fact that climate change can also disrupt the intestinal bacteria was previously unknown," explains Risely's colleague Dominik Schmid. The consequences of this association are devastating for the Kalahari meerkats. Combined, hot temperatures and tuberculosis infections make them 10 times less likely to survive. And meerkats are probably far from the only wild animals whose intestinal bacteria are being reshuffled by climate change.
Source: University of Ulm; Specialist article: Global Change Biology, doi: 10.1111/gcb.16877