Rhabdomys ecophysiology in natura

Understanding how organisms respond to seasonal variations in their environment can be a window to their potential adaptability, a classical problem in evolutionary ecology. In the context of climate change, inducing increased aridity and disruption of seasonality, it is crucial to study the extent and limits of species responsiveness.Here, the physiological response to food and water shortage during seasonally dry conditions were investigated. We studied populations of two rodent species of the genus <i>Rhabdomys</i>, one arid and one mesic, in a semi- arid zone where their range overlap in South Africa. We measured blood concentrations of markers of kidney and liver function, as well as body condition, at the onset and the end of the dry season.We found similar shifts in blood metabolite levels in the semi-arid populations of the two species, indicating malnutrition consistent with the observed degradation of habitat quality between the start and the end of the dry season. Furthermore, regardless of the period, differences between the two species in blood metabolite concentrations (ex: amylase, sodium, alkaline phosphatase) were observed, suggesting contrasting diets and water conservation abilities.Overall, we show that, as seasonal dry conditions worsen, organisms are increasingly affected by reduced food availability, and local adaptation to arid conditions may provide the arid species with an advantage to cope with semi- arid conditions. Our study suggests that even mild arid conditions could have a negative impact and questions resilience of animals to harsher arid conditions.探究生物如何响应环境季节变化，是洞悉其潜在适应性的重要窗口，亦是进化生态学领域的经典研究课题。在气候变化引发干旱加剧、季节节律紊乱的背景下，研究物种响应能力的范围与极限具有至关重要的意义。本研究聚焦于季节性干旱环境下生物对食物与水资源匮乏的生理响应展开探究。我们针对南非境内分布重叠的半干旱区域内，攀鼠属（Rhabdomys）的两个啮齿动物物种开展研究：其一为适旱物种，其二为湿生物种。我们于旱季初始与末期分别测定了二者的肝肾功能标志物血液浓度以及体况指标。研究发现，两个物种的半干旱种群血液代谢物水平均呈现相似变化趋势，这与旱季始末生境质量观测到的退化情况一致，提示二者均存在营养不良状况。此外，无论处于旱季的哪个阶段，两个物种的血液代谢物浓度（如淀粉酶、钠离子、碱性磷酸酶）均存在显著差异，这暗示二者的饮食策略与保水能力存在分化。综合来看，本研究表明：随着季节性干旱程度加剧，生物受到食物资源匮乏的影响愈发严重；而适旱物种对干旱环境的本地适应性，使其在半干旱生境中具备更强的应对能力。本研究同时提示，即便轻度干旱环境也可能对生物产生负面影响，这也引发了学界对动物应对极端干旱环境的恢复力的质疑。