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.

Interactions in single-host–parasite systems provide a tractable framework for understanding the ecological mechanisms that maintain community stability. Here, we integrated network topology, multidimensional niche analysis, and functional group delineation to investigate the adaptive strategies and assembly rules of a 12-species flea community on Mongolian gerbils (Meriones unguiculatus). The host–flea network was characterized by a stable, nested structure and exhibited strong seasonal dynamics, with connectivity peaking in summer and modularity increasing in autumn. To understand the niche mechanisms driving these patterns, we identified four key ecological gradients (Seasonal Climate, Host Physiology, Weather Exposure, Host Behavior) and quantified the niche breadth of each species along these axes. Our analysis revealed that the community was organized along a steep hierarchy of generalization. Two ”hyper-generalist” species (Nosopsyllus laeviceps kuzenkoui and Xenopsylla conformis conformis) dominated the community, exhibiting near-maximal niche breadth across all four dimensions and occupying the core of the co-occurrence network. A broad niche was a major determinant of a species’ role, correlating strongly with a wider range of exploited hosts (p < 0.05). In contrast, specialist species, such as the ”extreme specialist” (Ophthalmopsylla jettmari), were confined to the network’s periphery and a narrow subset of ecological conditions. Clustering based on the multidimensional niche profiles identified four distinct functional groups, reflecting a clear hierarchy of ecological strategies from dominant hyper-generalists to highly restricted specialists. Overall, by integrating a multidimensional niche framework with network analysis, this study demonstrates that a hierarchical niche structure, rather than complex trade-offs, is the primary organizing principle in this seasonally dynamic community, providing a more nuanced understanding of stability in parasitic systems.