Badás E P, Martínez J, Rivero de Aguilar Cachafeiro J, Miranda F, Figuerola J, Merino S
Department of Evolutionary Ecology, National Museum of Natural Sciences, Madrid, Spain.
J Evol Biol. 2015 Apr;28(4):896-905. doi: 10.1111/jeb.12615. Epub 2015 Mar 28.
Reproduction is inherently costly. Environmental stressors, such as infection and limited food resources, can compromise investment at each breeding attempt. For example, recent data on captive birds showed that increased reproductive effort accelerates ageing. However, the effects of nutritional status and infection on ageing remain unknown. Telomeres function as protective caps at the ends of eukaryotic chromosomes, and changes in telomere length is a commonly used proxy for ageing. To partially address the mechanisms of ageing following reproduction, we supplemented, medicated or administered a combined treatment to wild blue tits (Cyanistes caeruleus) breeding in central Spain during 2012. The nutritional supplement consisted of two different antioxidants, whereas the medication was an antimalarial treatment against blood parasites. We evaluated the effect of these manipulations on reproductive success and parasite loads in the first breeding season, and on changes in telomere length between two consecutive breeding seasons. Supplemented birds showed no reduction in blood parasite infections in 2012, although they exhibited higher body mass and fledging success. The antimalarial drugs reduced infections by several parasite species, but this had no effect on fitness parameters. In the following season, telomeres from supplemented birds had shortened less. Altogether, we found that supplementation with antioxidants provided fitness benefits in the short term and reduced telomere loss a year following treatment. Our results provide indirect empirical support for accelerated telomere loss as a cost of reproduction.
繁殖本身成本高昂。环境压力因素，如感染和食物资源有限，会影响每次繁殖尝试时的投入。例如，最近关于圈养鸟类的数据表明，增加繁殖努力会加速衰老。然而，营养状况和感染对衰老的影响仍不清楚。端粒在真核染色体末端起到保护帽的作用，端粒长度的变化是常用的衰老指标。为了部分阐明繁殖后衰老的机制，我们在2012年对西班牙中部野生蓝山雀（Cyanistes caeruleus）进行繁殖时，进行了补充营养、药物治疗或联合治疗。营养补充剂包含两种不同的抗氧化剂，而药物治疗是针对血液寄生虫的抗疟疾治疗。我们评估了这些操作对第一个繁殖季节繁殖成功率和寄生虫负荷的影响，以及对两个连续繁殖季节之间端粒长度变化的影响。补充营养的鸟类在2012年血液寄生虫感染率没有降低，尽管它们表现出更高的体重和 fledging success（此处原文可能有误，推测为 fledgling success，即雏鸟成活率）。抗疟疾药物减少了几种寄生虫物种的感染，但这对健康参数没有影响。在接下来的季节，补充营养的鸟类的端粒缩短得较少。总的来说，我们发现补充抗氧化剂在短期内提供了健康益处，并在治疗一年后减少了端粒损失。我们的结果为端粒加速损失作为繁殖成本提供了间接的实证支持。
