Stress load along a gradient of human disturbance in two sympatric lemur species

由于HPA轴以同样的方式对社会、生理和生态挑战做出反应，应激激素水平经常被用作健康的综合指标，特别是长期(慢性)压力与负面健康结果相关。在一个正在进行的关于两个密切相关的狐猴物种保护生理学的项目中，我们重点研究了压力在调节这两个物种对人为变化的敏感性中的关键作用。头发为评估长期压力提供了一个独特的矩阵，因为它综合了几周到几个月的HPA活动。通过使用头发皮质醇水平，我们将通过比较沿人类干扰梯度的压力负荷，来评估这样的假设，即慢速生活的专家C.medius比快速生活的多面手M.Murinus对人为变化更敏感。为了解释我们的发现，从而更有力地评估个人和人群的健康，我们将评估压力水平与另外两个健康指标--身体状况和寄生虫负荷--之间的关系。最后，我们将测试压力负荷的增加是否确实与生存概率的降低有关，并对这两个研究物种的这种关系进行量化。在预测的人口模型中，将敏感性估计与其人口结果相结合，为保护决策提供了可靠的基础。

Because the HPA axis responds in the same way to social, physiological and ecological challenges, stress hormone levels are often used as an integrative indicator of health, whereby especially long-term (chronic) stress is associated with negative health outcomes. Within an on-going project on the conservation physiology of two closely-related lemur species, the fat-tailed dwarf lemur (Cheirogaleus medius), and the grey mouse lemur (Microcebus murinus), we here focus on the pivotal role of stress in mediating the sensitivity of these species to anthropogenic change. Hair provides a unique matrix for assessing long-term stress, because it integrates HPA activity over several weeks to months. Using hair cortisol levels, we will evaluate the hypothesis that the slow-living specialist C. medius is more sensitive to anthropogenic change than the fast-living generalist M. murinus by comparing stress loads along a gradient of human disturbance. To interpret our findings and to thus assess individual and population health more robustly, we will then evaluate the relationship between stress levels and two more indicators of health, body condition and parasite loads. Finally, we will test whether increased stress loads are indeed associated with decreased survival probabilities and quantify this relationship for the two study species. Combining sensitivity estimates with its demographic consequences in predictive population models provides a sound basis for conservation decisions.