Saino N, Ferrari R P, Romano M, Rubolini D, Møller A P
Dipartimento di Biologia, Università degli Studi di Milano, Milano, Italy.
J Evol Biol. 2003 Nov;16(6):1127-34. doi: 10.1046/j.1420-9101.2003.00616.x.
Performance of animals may decline with age. The effects of senescence, however, may differ between the sexes because of differences in physiology and behaviour. Acquired immunity provides hosts with efficient mechanisms of anti-parasite defence, but the effect of senescence on immunocompetence has never been studied in natural populations. In the barn swallow (Hirundo rustica), primary antibody response to an antigen during one breeding season declined with age in females, while secondary response during the following breeding season declined with age in both sexes. Parasite-mediated sexual selection theory posits that male secondary sexual characters reveal resistance to parasites. Males with large tail ornaments had stronger primary response, retained larger antibody levels until the following year, but did not differ in secondary response compared with short-tailed males, as predicted if ornamentation reflects resistance to parasites. This is the first study showing that immunocompetence declines with age in any vertebrate under natural conditions.
动物的表现可能会随着年龄的增长而下降。然而，由于生理和行为上的差异，衰老的影响在两性之间可能有所不同。获得性免疫为宿主提供了有效的抗寄生虫防御机制，但衰老对免疫能力的影响从未在自然种群中进行过研究。在家燕（Hirundo rustica）中，雌性在一个繁殖季节对抗抗原的初次抗体反应随年龄下降，而在随后的繁殖季节，两性的二次反应均随年龄下降。寄生虫介导的性选择理论认为，雄性第二性征显示出对寄生虫的抵抗力。正如装饰反映对寄生虫的抵抗力所预测的那样，具有大尾饰的雄性有更强的初次反应，直到次年仍保持较高的抗体水平，但与短尾雄性相比，二次反应没有差异。这是第一项表明在自然条件下任何脊椎动物的免疫能力都会随年龄下降的研究。
