title: Increased extra-pair paternity in broods of aging males and enhanced recruitment of extra-pair young in a migratory bird.
abstract: Despite keen interest in extra-pair mating in birds, its adaptive significance remains unresolved. Here, we use a multi-year dataset to test whether traits of a female's social mate influence her propensity to produce extra-pair offspring in a population of house wrens, and whether producing extra-pair young has consequences for a female's fitness through effects on offspring survival. Females were most likely to produce extra-pair offspring when paired with old males and when paired with males on poor-quality territories, although this latter effect was marginally nonsignificant. Among offspring, the cutaneous immunity of within-pair young decreased as the age of their sires increased, but cutaneous immunity of extra-pair young was not affected by the age of their extra-pair sires or by the age of the males rearing them. Extra-pair offspring were more likely than within-pair offspring to return as breeding adults to the local population, with extra-pair sons being more likely to return as a breeder for multiple years. Our findings support the hypothesis that females produce extra-pair offspring to enhance their inclusive fitness beyond what they are capable of given the male with which they are socially paired.
authors.affiliation: Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, Illinois, 61790-4120. ekbowers@ilstu.edu.
authors.forename: E Keith
authors.initials: EK
authors.lastname: Bowers
authors.affiliation: Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, Illinois, 61790-4120.|Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, 14853.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Forsman
authors.affiliation: Department of Biological Sciences, Towson University, Towson, Maryland, 21252.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Masters
authors.affiliation: Department of Biological Sciences, Towson University, Towson, Maryland, 21252.
authors.forename: Bonnie G P
authors.initials: BG
authors.lastname: Johnson
authors.affiliation: Department of Biological Sciences, Towson University, Towson, Maryland, 21252.
authors.forename: L Scott
authors.initials: LS
authors.lastname: Johnson
authors.affiliation: Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, Illinois, 61790-4120.
authors.forename: Scott K
authors.initials: SK
authors.lastname: Sakaluk
authors.affiliation: Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, Illinois, 61790-4120.
authors.forename: Charles F
authors.initials: CF
authors.lastname: Thompson
mesh_terms: D000375:Aging; D025041:Animal Migration; D000818:Animals; D001522:Behavior, Animal; D005260:Female; D008297:Male; D052586:Mating Preference, Animal; D010835:Phytohemagglutinins / Q000276:immunology; D012098:Reproduction / Q000502:physiology*; D012867:Skin / Q000276:immunology; D020308:Songbirds / Q000276:immunology / Q000502:physiology*
chemical_list: D010835:Phytohemagglutinins
keywords: Extra-pair mating; Troglodytes aedon; house wren; life history; sex allocation