25.04.2019: Diseases of the gastrointestinal tract are being described with increasing frequency in the European brown hare. These are often due to changes in the gut microbiome, the microorganisms that make up the intestinal flora. Previously, however, little had been known about the exact causes. A recently published study by Vetmeduni Vienna now shows for the first time that habitat-related environmental factors could be responsible for the changes in the composition of intestinal bacteria.

In the study, the Vetmeduni Vienna research team, consisting of researchers from the Research Institute of Wildlife Ecology (Gabrielle Stalder) and two units from the Institute of Food Safety, Food Technology and Veterinary Public Health (working group of Evelyne Mann-Selberherr and Beate Pinior), analysed the microbiota of three hare populations living in different locations.

Environmental factors influence the gut microbiota of hares

The findings show that geographic location and possibly associated environmental factors had a significantly greater impact on the microbiota composition than host factors. Study director Gabrielle Stalder from the Research Institute of Wildlife Ecology at Vetmeduni Vienna: “The present pilot study is of great scientific importance, as the findings allow new hypotheses to be generated to explain how gut health can affect population fluctuations in hares. Our aim was to provide a broad foundation for generating hypotheses at the intersection of gut health and land use change in relation to European brown hares and potentially other species affected by the rapid modification or intensive use of their habitat. This information had been lacking despite being extremely important for understanding how environmental factors can affect the microbiome and thus the health of European brown hares and wildlife in general.”

The European brown hare – widely distributed yet regionally threatened

The European brown hare (Lepus europaeus) is a widely distributed and important wildlife species throughout Europe. Despite the classification of their population status as “least concern” by the International Union for Conservation of Nature (IUCN), significant population declines have been noted in the last 50–60 years, leading to a “near threatened” or “threatened” status on national red lists for some regional populations. A range of factors, including unfavourable climatic conditions, predation and multiple disease epidemics, have contributed to this unpleasant development. However, probably the greatest threat for this species is the intensification of modern agriculture – a hypothesis supported by the Vetmeduni Vienna study.

“Habitat fragmentation, agricultural mechanization, monocultures, unpredictable food availability as well as pesticide and fertilizer use could have an especially severe impact on species such as the European brown hare, as its diet is highly selective and focused on certain high-energy plant species. Furthermore, rabbits and hares are known to be very sensitive to any feed alterations and imbalances, causing disruption of the gut microbiota and gastrointestinal disease that may even result in the animals’ death,” says Gabrielle Stalder.

Gut bacteria: important for vertebrate health

Recent research in human and veterinary medicine has shown how much the microbiome, i.e. the composition of gut microbiota, affects the health of the host animal. A variety of host-specific factors, such as age, sex, body condition, genetics and host phylogeny, are known to shape the microbiota in an individual. Additionally, environmental factors, such as lifestyle, diet, climate and habitat conditions, as well as changes in land use, also impact the microbial composition in the gastrointestinal tract. However, this knowledge from domestic and laboratory animals cannot be easily transferred to wild animals. The present study by Vetmeduni Vienna therefore makes a significant contribution to better understanding the microbiome of wild animals.

The article “Gut microbiota of the European Brown Hare (Lepus europaeus)” by G. L. Stalder, B. Pinior, B. Zwirzitz, I. Loncaric, D. Jakupović, S. G. Vetter, S. Smith, A. Posautz, F. Hoelzl, M. Wagner, D. Hoffmann, A. Kübber-Heiss und E. Mann was published in Scientific Reports.