Tecot Stacey R, Irwin Mitchell T, Raharison Jean-Luc
School of Anthropology, University of Arizona, Tucson AZ, USA.
Laboratory for the Evolutionary Endocrinology of Primates, School of Anthropology, University of Arizona, Tucson AZ, USA.
Conserv Physiol. 2019 Feb 6;7(1):coz001. doi: 10.1093/conphys/coz001. eCollection 2019.
Glucocorticoids are metabolic byproducts of animals' physiological responses to ecological or social challenges and are thought to represent an adaptive response allowing beneficial responses to short-term challenges. Glucocorticoid metabolites (GCs) can be assayed non-invasively through faeces and therefore can be a useful tool to gauge the health of populations experiencing natural and/or anthropogenic stressors. However, the response of GCs to anthropogenic stressors varies, with both higher and lower GC levels reported. Here, we describe variation in GC secretion within eight diademed sifaka () groups across 1 year. These groups span a gradient of anthropogenic habitat disturbance, including groups in continuous forest ('CONT') and disturbed fragments ('FRAG'), and indicators of health suggest that FRAG groups are negatively impacted by habitat disturbance. We monitored phenology, used focal animal follows to quantify diet and collected faeces ( = 547) from which we quantified GC content using enzyme immunoassay. All groups showed elevated lean-season GCs, but with a single, brief peak. GCs were inversely correlated with feeding time. No overall effect of habitat (CONT vs. FRAG) was found, but the lean-season peak was significantly higher in CONT groups. There was a significant season*age-sex interaction; adult females had an attenuated lean-season response compared with groupmates. The observed lean-season 'challenge' is consistent with previous lemur studies, as well as mammals in general. Low and largely invariable GC levels in FRAG, within the context of observed health and nutritional declines, suggest that FRAG groups employ a strategy whereby the adrenal response to stressors is downregulated. More research is needed to contextualize our observations of GC variation and health on an individual level, both in terms of corroborating evidence for ecological and social stressors, and longer-term quantification of reproductive success and fitness.
糖皮质激素是动物对生态或社会挑战的生理反应的代谢副产物，被认为是一种适应性反应，能对短期挑战产生有益反应。糖皮质激素代谢物（GCs）可通过粪便进行非侵入性检测，因此可作为衡量受自然和/或人为压力源影响的种群健康状况的有用工具。然而，GCs对人为压力源的反应各不相同，有报道称其水平有高有低。在此，我们描述了8个冕狐猴群体在1年中的GC分泌变化。这些群体跨越了人为栖息地干扰的梯度，包括连续森林中的群体（“CONT”）和受干扰的片段中的群体（“FRAG”），健康指标表明FRAG群体受到栖息地干扰的负面影响。我们监测了物候，通过对焦点动物的跟踪来量化饮食，并收集粪便（n = 547），从中使用酶免疫测定法量化GC含量。所有群体在淡季时GCs水平都升高，但只有一个短暂的峰值。GCs与进食时间呈负相关。未发现栖息地（CONT与FRAG）的总体影响，但CONT群体在淡季的峰值显著更高。存在显著的季节*年龄-性别交互作用；成年雌性与同组其他成员相比，淡季反应减弱。观察到的淡季“挑战”与之前对狐猴的研究以及一般哺乳动物的情况一致。在观察到的健康和营养下降的背景下，FRAG群体中GCs水平较低且基本不变，这表明FRAG群体采用了一种下调肾上腺对应激源反应的策略。需要更多研究来将我们对GC变化和个体层面健康的观察置于具体情境中，这既包括对生态和社会压力源的确证证据，也包括对生殖成功和适应性的长期量化。
