Differences seen in the gut microbiota of desert-dwelling asses and Przewalski’s horses

There were significant differences in the microbes present, but overall diversity was similar, researchers report.
Photo by Frank.Vassen

Significant differences in the gut microbiota of Przewalski’s horses and wild asses that inhabit the Gobi Desert have been reported by researchers.

The scientists found that, while the results indicate that Przewalski’s horses are less adaptive to the Gobi Desert environment than wild asses, the functional performance of their microbiome is sufficient for them to coexist with other equids.

Liping Tang and her fellow researchers, writing in the journal Microorganisms, said the reintroduced Przewalski’s horse and the native Mongolian wild ass distributed in the Gobi’s Junggar Basin provide a good model for studying microbiome divergence between hosts with different adaptive abilities.

A total of 24 Przewalski’s horses from Germany, Britain and the United States were reintroduced in China in 1985 for captive breeding, and 27 individuals from breeding groups were released in 2001 into the Kalamaili Mountain Ungulate Nature Reserve, which lies deep within the Gobi Desert.

The free-ranging Przewalski’s horse population in the reserve has increased and is estimated to comprise more than 200 animals. The current population of Mongolian wild asses in the same reserve is estimated at more than 3000 individuals.

Przewalski’s horses are classified as endangered, while Asiatic wild asses are classified as near threatened on the International Union for Conservation of Nature Red List.

In the study, the researchers collected fresh fecal samples from eight adult wild horses and eight wild asses in the reserve for analysis.

They compared the functional microbiome of the two species to assess differences between the reintroduced Przewalski’s horses, and the asses, which have long been resident on the desert steppe.

Using molecular-based shotgun sequencing, the researchers identified a significant difference in microbiome composition between the two species in terms of the microbes present and their relative abundances. However, the overall diversity of microbes between the two equids was similar.

“The functional profile seemed to converge between the two hosts, with genes related to core metabolism function tending to be more abundant in wild asses,” they said.

While the wild horses differed in their microbial composition, they still harbored a stable microbial functional core, which the researchers said may enable them to survive in challenging habitats.

A higher abundance of beneficial microbial families, such as Akkermansia, and genes related to metabolism pathways and enzymes, such as lignin degradation, may contribute to more diverse diet choices and larger home ranges for wild asses, the authors said.

Discussing their findings, the study team noted that intestinal microbial diversity has been recognized as a new biomarker of health and metabolic performance in humans.

“It seems intuitive that wild asses, with higher energy digestibility and more flexible diets, should harbor more diverse gut microbiota than wild horses. However, wild asses have slightly lower microbial diversity than reintroduced wild horses, which may be due to their smaller body size.”

Microbial community diversity has been shown to decrease with host mass in herbivorous hosts.

Overall, the results indicated that while Przewalski’s horses were less adaptive to the Gobi Desert environment than wild asses, their microbiome functional performance was still sufficient for them to coexist with other equids.

“Given the complexity of feeding behaviors under natural conditions, the relationship between diet diversity and gut microbiota diversity in the wild is still unexplored,” they added.

The study team said their work provides insights into the structure and function of the microbiome in equids living in the same desert area

“Our findings show that the microbiome in reintroduced horses and native Asiatic wild asses differ in taxonomic composition but are consistent in functional profile, indicating that the overall metabolic functional performance of gut microbes is not significantly associated with adaptation to arid environments in wild equids.

“However, we noted taxa and genes related to certain metabolic or functional pathways tend to be more abundant in wild asses, which requires further investigation.”

They said further investigations involving microbial profiling, diet investigation and validation experiments are required to learn more about the complexity of host-microbial interaction.

“Knowledge of the gut microbiomes of these two wild equid species may provide helpful insights for improving the performance of endangered, relocated species,” they said.

The study team comprised Tang, Yunyun Gao, Liping Yan, Huiping Jia, Defu Hu, Dong Zhang and Kai Li, all with Beijing Forestry University; Hongjun Chu, with the Xinjiang Academy of Forestry Sciences; Xinping Ma, with the Xinjiang Kalamaili Mountain Ungulate Nature Reserve Management Center; and Lun He and Xiaoting Wang, with the China Wildlife Conservation Association in Beijing.

Tang, L.; Gao, Y.; Yan, L.; Jia, H.; Chu, H.; Ma, X.; He, L.; Wang, X.; Li, K.; Hu, D.; Zhang, D. Comparative Analysis of Microbiome Metagenomics in Reintroduced Wild Horses and Resident Asiatic Wild Asses in the Gobi Desert Steppe. Microorganisms 2022, 10, 1166. https://doi.org/10.3390/microorganisms10061166

The study, published under a Creative Commons License, can be read here


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