Altitude- and Sex-Specific Telomere Dynamics in the Montane Salamander Pachytriton cheni

Environmental stressors and sex-specific life-history strategies synergistically shape senescence patterns in ectotherms, yet their interactive effects on telomere dynamics remain poorly understood. This study investigates how altitude-related environmental factors and sexual dimorphism drive telomere length variation in the montane salamander Pachytriton cheni across an elevational gradient (850-1350 m) in Qingliangfeng Nature Reserve, China. Using qPCR, skeletochronology and physiological assays, we analysed telomere length, age, oxidative damage markers and environmental parameters in 100 individuals. Results revealed a significant positive correlation between altitude and relative telomere length (RTL), with males exhibiting stronger elevational dependence than females. Multivariate models identified divergent environmental effects: higher flow velocity promoted telomere maintenance, whereas elevated water temperature, dissolved oxygen and dietary diversity accelerated attrition. Despite lower mobility, females maintained longer telomeres than males, suggesting sex-specific trade-offs favouring somatic maintenance over reproductive investment. Oxidative damage markers (malondialdehyde and protein carbonyls) were elevated at lower altitudes, aligning with free radical theory predictions. These findings highlight the interplay of environmental stressors (e.g., thermal and oxidative pressures) and sex-driven energy allocation in shaping telomere dynamics. Our work underscores the importance of integrating climate resilience into conservation strategies for high-altitude amphibians, particularly as habitat degradation and climate change threaten montane ecosystems. Our findings on the genotype-environment-sex interactions in P. cheni provide a conceptual framework for predicting how ectotherms may senesce in rapidly changing environments.