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.

The O. sibirica (Orientallactaga sibirica), a member of the family Dipodidae, is widely distributed across Central Asia and plays a significant role in grassland ecosystems. While substantial ecological data on this species exists in China, research on intraspecific cranial variation is limited, and no extensive surveys have been conducted within its Chinese distribution range. This study aims to address this gap by capturing O. sibirica specimens from various geographical regions within China, conducting geometric morphometric analyses on their skulls, and examining the influence of current climatic conditions. Additionally, we predict changes in the suitable habitat areas for O. sibirica in China under future climate scenarios. Our results indicate that the major cranial variations in O. sibirica occur in the nasal, parietal, maxilla near the nasal end, zygomatic arch, and preorbital bridge. These features result in skulls from northeastern China clustering furthest from those in the Qinghai-Tibet Plateau. Skull size is primarily influenced by precipitation, whereas skull shape is affected by longitude, altitude, and temperature. Under future global changes, the suitable habitat for O. sibirica is likely to shrink, with the distribution centroid shifting towards higher latitudes in a northeasterly direction. Our analysis reveals that the cranial morphology of O. sibirica exhibits divergent adaptation across different geographical regions, particularly in the Qinghai-Tibet region, which we suggest should be designated as a new subspecies. Concurrently, future global changes are anticipated to alter the extent of suitable habitats in China, necessitating proactive measures to prevent potential rodent outbreaks.