School of Biological Sciences, Monash University, Clayton, VIC, 3800, Australia.
J Comp Physiol B. 2012 Jan;182(1):139-55. doi: 10.1007/s00360-011-0598-7. Epub 2011 Jun 28.
Although the vertebrate stress response is essential for survival, frequent or prolonged stress responses can result in chronic physiological stress, which is associated with a suite of conditions that can impair survivorship and reproductive output. Anthropogenic habitat fragmentation and degradation are potential stressors of free-living vertebrates, and in theory could result in chronic stress. To address this issue, we compared haematological indicators of stress and condition in agile antechinus (Antechinus agilis) populations in 30 forest fragments and 30 undisturbed, continuous forest sites (pseudofragments) in south-eastern Australia over 2 years. In peripheral blood, the total leucocyte count was lower and the neutrophil/lymphocyte ratio and percentage of eosinophils in the total leucocyte population was higher in fragment than pseudofragment populations, indicating that fragment populations were probably experiencing higher levels of stress hormone-mediated and/or parasite infection-related chronic physiological stress. The total erythrocyte count and haematocrit were higher and mean erythrocyte haemoglobin content was lower in fragment than pseudofragment populations. This suggests that fragment populations showed possible signs of regenerative anaemia, a syndrome associated with elevated hypothalamus-pituitary-adrenal axis mediated stress. However, mean erythrocyte volume was also lower in fragments, and red blood cell distribution width did not differ between the study populations, findings which were not consistent with this diagnosis. Whole blood and mean cell haemoglobin concentrations were similar in fragment and pseudofragment populations. We suggest that where anthropogenic activity results in habitat fragmentation and degradation, chronic stress could contribute to a decline in agile antechinus populations. The broader implication is that chronic stress could be both symptomatic of, and contributing to, decline of some vertebrate populations in anthropogenically fragmented and degraded habitats.
尽管脊椎动物的应激反应对生存至关重要，但频繁或长期的应激反应会导致慢性生理应激，从而导致一系列可能影响生存和繁殖的情况。人为的生境破碎化和退化是自由生活的脊椎动物的潜在应激源，从理论上讲，它们可能导致慢性应激。为了解决这个问题，我们在澳大利亚东南部比较了 30 个森林片段和 30 个未受干扰的连续森林（伪片段）中的敏捷负鼠（Antechinus agilis）种群的应激和健康指标，为期 2 年。在外周血液中，白细胞总数在片段种群中低于伪片段种群，中性粒细胞/淋巴细胞比值和白细胞总数中的嗜酸性粒细胞百分比在片段种群中较高，表明片段种群可能经历了更高水平的应激激素介导和/或寄生虫感染相关的慢性生理应激。红细胞总数和血细胞比容在片段种群中高于伪片段种群，平均红细胞血红蛋白含量在片段种群中较低。这表明片段种群可能出现再生性贫血的迹象，这是一种与下丘脑-垂体-肾上腺轴介导的应激有关的综合征。然而，片段中的平均红细胞体积也较低，并且红细胞分布宽度在研究种群之间没有差异，这与该诊断不一致。片段和伪片段种群中的全血和平均细胞血红蛋白浓度相似。我们认为，在人为活动导致生境破碎化和退化的地方，慢性应激可能导致敏捷负鼠种群减少。更广泛的意义是，慢性应激可能是某些脊椎动物种群在人为破碎和退化栖息地中减少的症状和原因。
