Abstract
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.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
