Humoral immune response in relation to senescence, sex and sexual ornamentation in the barn swallow (Hirundo rustica)

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.

Female collared flycatchers adjust yolk testosterone to male age, but not to attractiveness

“…Moreover, older males are likely to be of higher genetic quality (Brooks and Kemp, 2001) although this may depend on the trade-off between mating effort and survival. Hence, females mating with such males may either obtain direct fitness benefits, if older males have territories of high quality (Alatalo et al, 1986a), provide superior parental care through improved foraging or defense against predators (Alatalo et al, 1986b;Marchetti and Price, 1989;Yasukawa, 1981) or pathogens (Saino et al, 2003), or provide genetic benefits, if viability is heritable (Brooks and Kemp, 2001;Trivers, 1972). As a result, females would benefit from differential allocation depending on the age of their mate.…”

Avian immunosenescence

“…Barn swallows were immunized with Newcastle disease virus (NDV) vaccine twice in successive breeding seasons. Females of one to 3 years old showed an age-related decline in anti-NDV response during the first year, and both females (2 to 4 years old) and males (2 to 6 years old) showed an age-related decline in secondary anti-NDV response in the second year (Saino et al 2003). Female collared flycatchers of three age groups (young: 1 year, middle-aged: 3 years and old: 5Y6 years) were immunized with sheep red blood cells (SRBC) while feeding their nestlings.…”

“…Measurements of age-related changes in immunity have been made in at least four bird species: barn swallows (Hirundo rustica), collared flycatchers (Ficedula albicollis), common terns (Sterna hirundo) and ruffs (Philomachus pugnax) (Saino et al 2002;Apanius and Nesbit 2003;Cichón et al 2003;Lozano and Lank 2003;Saino et al 2003). The studies on barn swallows, flycatchers and ruffs were made in relation to ecological questions.…”

Senescence in Animals: Why Evolutionary Theories Matter

“…In fact, in recent years, several studies have demonstrated demographic senescence (Austad, 1993;Bronikowski et al, 2002;Ericsson et al, 2001;Orell & Belda, 2002) and reproductive senescence in mammals and birds in their habitats (Austad, 1993;Broussard et al, 2003;Ericsson et al, 2001;Reid et al, 2003;Saino et al, 2003).…”