Abstract: Trophic niche partitioning is one of the principal mechanisms maintaining the coexistence of species in communities. There is relatively little information on trophic niche partitioning of rodents in Chinese deserts. Here we investigated the diets of two sympatric jerboa species ( Dipus sagitta and Orientallactaga sibirica) in Inner Mongolia. We sampled hair and feces in different seasons in 2021 in Alxa Desert, a typical temperate desert located in the central area of the arid and semi-arid regions of China and Mongolia. We conducted a stable isotope analyses(δ 15N, δ 13C) of the hair and DNA metabarcoding analyses of feces to determine the trophic niche and diets of the jerboa speciesin different seasons (Spring, Summer, and Autumn). The diet of D.sagitta shifted largely with season, the species can be characterized as a generalist, its main foods include: Corispermum mongolicum, Nitraria tangutorum, Salsola tragus, Sarcozygium xanthoxylon. Whereas O. sibirica had a stable choice for the main food in their diet, it tended towards specialization, mainly feeding on Salsola tragus and Ammopiptanthus mongolicus, especially in autumn.We found that the two sympatric species had limited overlap of dietary, and their core trophic niches were separated in all seasons. When food was scarce, both jerboa species’ expanded their diet range, but it led to increased similarity of intra-species diets. Therefore, higher intra-specific diet and trophic niche overlap are occurring across the seasons between genders (male and female). This study demonstrates that these jerboa species partitioned their nutritional niches thereby achieving coexistence.

The gut microbiome can be one pathway by which a host rapidly acclimates and adapts to its ecological environment. Exploring how the microbiome has evolved to differ between hosts with different diets provides insights into the profound interactions between hosts and microbes within these systems. In this study, we used DNA metabarcoding techniques and macrogenomic prediction techniques to study the gut microbes of four desert rodent species with different feeding strategies in the same habitat. One species is herbivorous (Spermophilus alashanicus), one is seed-eating (Phodopus roborovskii), another is omnivorous (Dipus sagitta), and the last (Orientallactaga sibirica) has a diet with a relatively high proportion of meat. Diets rich in plants and insects can be challenging to digest due to the abundance of indigestible fiber and stable chitin, respectively. Out of the species studied, the herbivorous Spermophilus alashanicus has the highest density of UCG-005 genes and the highest predicted abundance of genes related to digestive complexity. The composition of Phodopus roborovskii’s microbiome has the highest variation between individuals, yet Phodopus roborovskii has the highest predicted abundance of genes associated with simple sugars—reflecting this species’ potential adaptability to the fiber within plant seeds and its constraints brought about by its smaller body size. The most insectivorous species, Orientallactaga sibirica, exhibits the highest predicted abundance of genes related to chitin degradation. This study has enhanced our understanding of the gut microbiota in the intestines of rodents as they adapt to various dietary strategies.