title: Joint associations of blood plasma proteins with overwinter survival of a large mammal.
abstract: In many wild animal populations, hosts are at risk of parasites and malnutrition and resource costs of defence may be difficult to afford. We postulate that proteins, important in homeostasis and immunity, play a complex but central role in condition dependence and resource costs of mammalian immune defence. To test this, we measured plasma concentrations of albumin, total proteins. Self-reactive antibodies and parasite-specific IgG in female Soay sheep. Using a principal component analysis, we found a new metric of condition reflecting individual variation in acquisition, assimilation and/or recycling of plasma proteins that predicted overwinter survival. Controlling for this metric, an age-dependent trade-off between antibody titres and protein reserves emerged, indicating costs of mounting an antibody response: younger individuals survived best when prioritising immunity while older individuals fared better when maintaining high-protein nutritional plane. These findings suggest fascinating roles for protein acquisition and allocation in influencing survival in wild animal populations.
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA.
authors.forename: Romain
authors.initials: R
authors.lastname: Garnier
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA.
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Cheung
authors.affiliation: Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Watt
authors.affiliation: Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
authors.forename: Jill G
authors.initials: JG
authors.lastname: Pilkington
authors.affiliation: Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
authors.forename: Josephine M
authors.initials: JM
authors.lastname: Pemberton
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA.
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Graham
mesh_terms: D000418:Albumins / Q000378:metabolism*; D000818:Animals; D001798:Blood Proteins / Q000378:metabolism*; D005260:Female; D007074:Immunoglobulin G / Q000097:blood*; D008136:Longevity; D012621:Seasons; D034561:Sheep, Domestic / Q000097:blood / Q000502:physiology*
chemical_list: D000418:Albumins; D001798:Blood Proteins; D007074:Immunoglobulin G
keywords: 
  Ovis aries
  ; Disease ecology; ecological immunology; nutritional ecology