Immune response of nestling warblers varies with extra-pair paternity and temperature.
Extra-pair mating is widespread in birds, but its adaptive function remains unclear. It is often suggested that females obtain superior genes for their offspring as a consequence of extra-pair mating, but the evidence is limited. In this study, we examined the hypothesis that extra-pair mating provides females with offspring that have superior immune responses. We found that the T-cell-mediated immune response of extra-pair young was stronger than that of within-pair young in common yellowthroats (Geothlypis trichas). This paternity effect occurred when we compared all nestlings in the population, as well as in comparisons of both paternal and maternal half-siblings. Paternal half-siblings had a stronger immune response when they were produced with extra-pair females than with the male's social mate, which suggests that the greater immune response of extra-pair young was caused by nonadditive (compatible) genetic effects. However, these patterns were only significant in the colder of 2 years. Immune response was related positively to air temperature and nestlings had a stronger immune response in the warmer year. We suggest that such environmental variation could obscure the genetic benefits of extra-pair mating.
Garvin
Julia C
JC
Department of Biological Sciences, PO Box 413, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA.
Abroe
Betsy
B
Pedersen
Marc C
MC
Dunn
Peter O
PO
Whittingham
Linda A
LA
D000818:Animals; D005260:Female; D008297:Male; D012726:Sexual Behavior, Animal; D020308:Songbirds / Q000033:anatomy & histology / Q000276:immunology* / Q000502:physiology; D013601:T-Lymphocytes / Q000276:immunology; D013696:Temperature