Ecological immunology proposes that the optimal immune defence, and the costs coming with it, vary across environments. In environments with higher pathogen load, the immune system should experience greater challenges and, therefore, investment in maintaining it should be higher. The biomarker neopterin allows monitoring of innate immune responses, and is therefore an ideal tool to investigate the effects of ecological variables on the immune system. Here, we compared urinary neopterin levels of apparently healthy chimpanzees without acute symptoms of sickness across two environments: in captivity (22 zoos) and in the wild (two populations). Our results revealed that urinary neopterin levels were nearly twice as high in wild compared to captive chimpanzees, independent of chimpanzee subspecies. We conclude that wild chimpanzees experience more frequent immune challenges in comparison to captive individuals. Therefore, wild individuals have to allocate more energy to immune function and away from reproduction and growth. Our data indicate that the generally delayed development of wild animals in comparison to captive individuals might not only be related to lower energy intake but might result from greater energy allocations to immune function. Finally, our data highlight the importance of understanding immune costs for accurate characterization of energy budgets in animals.

中文翻译：

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野生，健康的黑猩猩中的新蝶呤水平升高表明对非特异性免疫系统的不断投资

生态免疫学认为，最佳的免疫防御及其成本会因环境而异。在病原体负荷较高的环境中，免疫系统应面临更大的挑战，因此，维护免疫系统的投资应更高。生物标志物新蝶呤可以监测先天免疫反应，因此是研究生态变量对免疫系统影响的理想工具。在这里，我们比较了在两种环境中圈养（22个动物园）和野生环境（两个种群）中看似健康的黑猩猩（没有急性疾病症状）的尿新蝶呤水平。我们的结果表明，与圈养黑猩猩相比，独立于黑猩猩亚种的野生尿中新蝶呤水平几乎是野生黑猩猩的两倍。我们得出的结论是，与圈养的个体相比，野生黑猩猩经历的免疫挑战更为频繁。因此，野生个体必须分配更多的能量用于免疫功能，并远离繁殖和生长。我们的数据表明，与圈养个体相比，野生动物普遍发育迟缓不仅可能与能量摄入减少有关，而且可能是由于对免疫功能分配更多能量所致。最后，我们的数据强调了了解免疫成本对动物能量预算的准确表征的重要性。我们的数据表明，与圈养个体相比，野生动物普遍发育迟缓不仅可能与能量摄入减少有关，而且可能是由于对免疫功能分配更多能量所致。最后，我们的数据强调了了解免疫成本对动物能量预算的准确表征的重要性。我们的数据表明，与圈养个体相比，野生动物普遍发育迟缓不仅可能与能量摄入减少有关，而且可能是由于对免疫功能分配更多能量所致。最后，我们的数据强调了了解免疫成本对动物能量预算的准确表征的重要性。