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.

理解生物如何响应环境中的季节性变化，是洞察其潜在适应性的窗口——这是进化生态学（evolutionary ecology）中的经典问题。在气候变化导致干旱度增加和季节性紊乱的背景下，研究物种响应能力的范围与限度至关重要。本研究探讨了季节性干旱条件下生物对食物和水资源短缺的生理响应。我们研究了南非半干旱地区两种<em>Rhabdomys</em>属啮齿动物的种群——一种适应干旱环境，另一种适应湿润环境——它们的分布范围在此区域重叠。我们在旱季初期和末期测量了它们的肾功能与肝功能标志物的血液浓度，以及身体状况。我们发现两种物种的半干旱种群血液代谢物水平发生了相似变化，这表明营养不良，与旱季始末观察到的栖息地质量退化一致。此外，无论时期如何，两种物种在血液代谢物浓度（如淀粉酶、钠、碱性磷酸酶）上均存在差异，这表明它们的饮食结构和保水能力有所不同。总体而言，我们的研究表明，随着季节性干旱条件加剧，生物受食物可获得性降低的影响日益显著，而对干旱环境的局部适应可能使干旱物种在应对半干旱条件时具有优势。本研究还指出，即使是轻度干旱条件也可能产生负面影响，并对动物在更严酷干旱条件下的恢复力（resilience）提出了疑问。