Population and Spatial Features Impact the Gut Phageome–Bacteriome Structure and Interactions in a Mammal Species Living in Fragmented Habitats

The mammalian gut microbiome composition has been shown to promote host adaptation to ecological environments. However, the variation in the gut phageome and bacteriome composition at both the population level and spatial scale in wild animals has not been well investigated. Here, we used viral metagenomes and 16S rRNA gene sequencing to explore how these characteristics affect the gut microbiome of Przewalski's gazelle, an endangered group-living ungulate that lives in several fragmented habitats due to anthropogenic activities. The results revealed that population and habitat geographic characteristics collectively explained much more of the variation in phageome and bacteriome compositions than did host-associated factors. Both gut phage and bacterial diversity were positively associated with population size, and differentiation in gut microbiome diversity increased with geographic distance among populations. Additionally, the gut phage and the bacterial hosts displayed similar patterns in composition across habitats, indicating that the microbiome may exhibit complex interactions in response to the environment. For the first time, our study reveals the important roles of population and habitat geographic characteristics in driving spatial patterns of gut microbiome structures in wild animals and highlights the interactions between gut phages and the bacteriome in adaptation to living environments under the influence of human disturbances.