Yongling Jin

Rising global temperatures lead to a continuous increase in the frequency and intensity of extreme weather events, such as droughts and floods, posing serious threats to terrestrial homeotherms. However, adaptive changes in respiratory metabolism and molecular mechanisms in lung tissues of small mammals under extreme water shortage conditions remain unclear. This study hypothesized that small desert mammals can adapt to extreme water shortage environments by regulating the plasticity of lung tissue gene expression and respiratory metabolism. Using 29 wild-caught Siberian jerboas (Orientallactaga sibirica) as subjects, we implemented a 12-day complete water deprivation protocol to simulate extreme aridity. Body weight, food intake, and daily energy expenditure (DEE) were monitored throughout the experiment. Whole-transcriptome sequencing of lung tissues was performed to profile mRNA, circRNA, and miRNA expression, with competitive endogenous RNA (ceRNA) network analysis to explore molecular mechanisms underlying lung adaptation to water deprivation. Over the 12-day water deprivation (WS) period, Orientallactaga sibirica (O. sibirica) exhibited a 30.3% reduction in body mass and a 68.1% decrease in food intake relative to the baseline level. DEE during the peak activity period at the end of the experiment was 12.6% lower in the WS group compared to the control group. In lung tissue, structural integrity-related genes (Mybl2, Ccnb1) were downregulated. A key finding was that circ_0015576 exhibits a significant positive correlation with the potassium channel gene Kcnk15 and a robust negative correlation with miR-503-5p—suggesting that circ_0015576 functions as a competing endogenous RNA (ceRNA) to sequester miR-503-5p and thereby derepress Kcnk15 expression. Core regulatory genes (ApoA4, Dusp15 etc.) were also coordinately downregulated. Collectively, these results indicate that O. sibirica reduces overall energy expenditure, which may be associated with lung gene expression plasticity, such as those related with lung cell proliferation, pulmonary function, and gas exchange efficiency. This metabolic downregulation facilitates energy conservation under severe water scarcity.

Rodents, as a core component of desert ecosystems and an important indicator of environmental changes, are ideal subjects for studying the impacts of fluctuations in climatic conditions on wildlife. Based on field data from the southern Alxa Desert (2014–2020), this study constructed an ecosystem structure network integrating local/metacommunities, climate, soil, and plant communities. Combined with structural equation modeling, we explored the response mechanisms of rodent communities to climatic conditions across multiple scales. The results showed the following: the α-diversity of local and metacommunities exhibited convergent seasonal patterns, with greater impacts from human disturbances than interannual effects, as well as coexisting species turnover and nesting in metacommunities. Precipitation directly affected metacommunity abundance and diversity and indirectly influenced both community types via vegetation, while temperature directly regulated community characteristics; metacommunities were formed via the coupling of local communities through species migration and habitat filtering, reflecting complex links between local and regional processes. This research provides scientific support for predicting desert ecosystem dynamics and guiding conservation management.

Organisms living in desert habitats face multiple simultaneous pressures, such as high temperatures and arid, and the population dynamics and community diversity of small rodents are strongly affected by climate extremes. However, the potential mechanisms by which desert rodents adapt to arid remain largely unexplored. Here, we assembled a 3.18 Gb genome, including 25,812 protein-encoding genes, for Orientallactaga sibirica, which is widely distributed across both arid and semihumid environments in Eurasia. O. sibirica has longer ears and hind limbs to enhance heat dissipation, which may be related with the positively selected genes, such as Fgf10, Fgf11, Hoxc4, Hoxd1, and Bmp4. The renal transcriptome revealed increased fat and carbohydrate metabolism for metabolic water production in O. sibirica residing in arid habitats. Pathways such as material metabolism, oxidative stress response, osmoregulation, and water and salt reabsorption were enriched in candidate genes, such as Avp, Ang, and Ace, under positive selection in O. sibirica. Moreover, amino acid replacement was observed in the protein sequences of seven candidate genes, including Aldh7a1, Lnpep, Wnk4, C1qc, and Awat2, and these specific amino acid replacements of genes such as Umod and Scnn1a were related to unique osmoregulation, osmotic protection and water retention compensation mechanisms. Water deprivation under laboratory conditions induced the upregulation of Umod and Aldh7a1 expression, further supporting the results observed in the wild population. These findings demonstrate that the positively selected genes related to limb development and specific amino acid replacements in the genes Umod and Scnn1a for unique osmoregulation in the renal vascular system may contribute to arid adaptation in the desert rodent species O. sibirica. This study provides novel insights into the adaptive evolution of desert small mammals and can serve as a reference for future research on renal damage-related diseases such as human kidney stones and salt-sensitive hypertension.