title: Sex-biased immunity is driven by relative differences in reproductive investment.
abstract: Sex differences in immunity are often observed, with males generally having a weaker immune system than females. However, recent data in a sex-role-reversed species in which females compete to mate with males suggest that sexually competitive females have a weaker immune response. These findings support the hypothesis that sexual dimorphism in immunity has evolved in response to sex-specific fitness returns of investment in traits such as parental investment and longevity, but the scarcity of data in sex-reversed species prevents us from drawing general conclusions. Using an insect species in which males make a large but variable parental investment in their offspring, we use two indicators of immunocompetence to test the hypothesis that sex-biased immunity is determined by differences in parental investment. We found that when the value of paternal investment was experimentally increased, male immune investment became relatively greater than that of females. Thus, in this system, in which the direction of sexual competition is plastic, the direction of sex-biased immunity is also plastic and appears to track relative parental investment.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada M5S 3G5 crystal.vincent@utoronto.ca.
authors.forename: Crystal M
authors.initials: CM
authors.lastname: Vincent
authors.affiliation: Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada L5L 1C6.
authors.forename: Darryl T
authors.initials: DT
authors.lastname: Gwynne
mesh_terms: D000222:Adaptation, Physiological / Q000276:immunology; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D005260:Female; D007121:Immunocompetence / Q000502:physiology*; D008297:Male; D014442:Monophenol Monooxygenase / Q000276:immunology; D009987:Orthoptera / Q000276:immunology* / Q000502:physiology; D010641:Phenotype; D012098:Reproduction / Q000502:physiology*; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal / Q000502:physiology
chemical_list: D014442:Monophenol Monooxygenase
keywords: Kawanaphila nartee; immunocompetence; sexually dimorphic immunity