Ecophysiology of boreal small mammals: physiological variation and environmental change

为了生存和繁殖，所有生物都必须在一定的时间尺度上平衡能量的摄入和输出。因此，影响能量平衡的因素将对进化乃至所有生态过程产生强烈影响。我的项目的长期目标是了解小型、自由生活的哺乳动物在面对环境变化时维持能量平衡的机制变化。这对于理解生理特征的进化以及预测气候变化对野生动物和生态系统的影响非常重要。在短期内，我的团队将专注于两组相关机制的变异性：a)与全动物能量消耗相关的性状，如代谢率和体温调节；b)所谓的“压力轴”的活动，它有助于调节能源使用的可预测的季节性变化，以及通过压力激素对急性环境压力源（如捕食风险）的反应。我们将在低繁殖率的长寿哺乳动物（蝙蝠、翼翅目）和高繁殖率的短寿命哺乳动物（鼩鼱、鼩鼱科）中测试这些性状对环境变化的反应假设，以评估生活史对生理变化的影响。理论预测，长寿的物种在应对环境变化时应该更灵活，因为选择压力有利于适应它们一生中经历的广泛条件。短命物种的个体应该不那么灵活，但这些物种可能由于更短的世代时间而受到更快速的进化变化的影响。我们将通过测量野生捕获动物的氧气消耗率、二氧化碳产生率和体温来研究全动物代谢，并通过分析血液或粪便中的应激激素来研究应激轴活动。从长期来看，我们将测试这样一个假设，即在蝙蝠和鼩鼱种群中，这些特征的年际变化与气候变化的直接和间接影响有关。

All organisms must balance energy intake against output on some timescale to survive and reproduce. Therefore, factors affecting energy balance will exert strong influence on evolution and, indeed, all ecological processes. The long-term goal of my program is to understand variation in mechanisms used by small, free-living mammals to maintain energy balance in the face of environmental change. This is important for understanding the evolution of physiological traits, and predicting consequences of climate change for wildlife and ecosystems. In the short-term, my group will focus on variability in two related sets of mechanisms: a) traits associated with whole-animal energy expenditure, such as metabolic rate and thermoregulation; and b) activity of the so-called "stress axis", which helps mediate predictable seasonal changes in energy use, and responses to acute environmental stressors (such as predation risk) via stress hormones. We will test hypotheses about responses of these traits to environmental change in long-lived mammals with low reproductive rates (bats, Chiroptera) vs. short-lived species with high reproductive rates (shrews, Soricidae) to assess the influence of life history on physiological variation. Theory predicts that long-lived species should be more flexible in response to environmental change because of selection pressure favouring adaptation to the broad range of conditions experienced during their lives. Individuals of short-lived species should be less flexible but these species may be subject to more rapid evolutionary change because of shorter generation times. We will study whole-animal metabolism by measuring rates of O2 consumption, CO2 production and body temperature in wild-captured animals, and stress axis activity by assaying stress hormones in blood or feces. Over the long-term we will test the hypothesis that inter-annual variation in these traits, within populations of bats and shrews, is correlated with both direct and indirect effects of climate change.