title: Sexual selection explains more functional variation in the mammalian major histocompatibility complex than parasitism.
abstract: Understanding drivers of genetic diversity at the major histocompatibility complex (MHC) is vitally important for predicting how vertebrate immune defence might respond to future selection pressures and for preserving immunogenetic diversity in declining populations. Parasite-mediated selection is believed to be the major selective force generating MHC polymorphism, and while MHC-based mating preferences also exist for multiple species including humans, the general importance of mate choice is debated. To investigate the contributions of parasitism and sexual selection in explaining among-species variation in MHC diversity, we applied comparative methods and meta-analysis across 112 mammal species, including carnivores, bats, primates, rodents and ungulates. We tested whether MHC diversity increased with parasite richness and relative testes size (as an indicator of the potential for mate choice), while controlling for phylogenetic autocorrelation, neutral mutation rate and confounding ecological variables. We found that MHC nucleotide diversity increased with parasite richness for bats and ungulates but decreased with parasite richness for carnivores. By contrast, nucleotide diversity increased with relative testes size for all taxa. This study provides support for both parasite-mediated and sexual selection in shaping functional MHC polymorphism across mammals, and importantly, suggests that sexual selection could have a more general role than previously thought.
authors: Odum School of Ecology, University of Georgia, Athens, GA 30602, USA. jcwinternitz@gmail.com
authors: J C
authors: JC
authors: Winternitz
authors: S G
authors: SG
authors: Minchey
authors: L Z
authors: LZ
authors: Garamszegi
authors: S
authors: S
authors: Huang
authors: P R
authors: PR
authors: Stephens
authors: S
authors: S
authors: Altizer
mesh_terms: D000818:Animals; D008285:Major Histocompatibility Complex; D008322:Mammals / Q000235:genetics / Q000382:microbiology / Q000469:parasitology / Q000502:physiology*; D052586:Mating Preference, Animal; D011110:Polymorphism, Genetic; D013045:Species Specificity
keywords: major histocompatibility complex; mate choice; meta-analysis; parasite richness; parasite-mediated selection; phylogenetic comparative methods
references: Eur J Immunol. 2004 Jan;34(1):7-17
references: 14971025
references: Mol Biol Evol. 2011 Apr;28(4):1455-68
references: 21183613
references: Front Zool. 2005 Oct 20;2:16
references: 16242022
references: Nature. 2007 Mar 29;446(7135):507-12
references: 17392779
references: Immunogenetics. 2012 Jul;64(7):535-47
references: 22426641
references: PLoS One. 2012;7(5):e37562
references: 22649541
references: Science. 2000 Nov 10;290(5494):1168-70
references: 11073457
references: Evolution. 2013 May;67(5):1406-19
references: 23617917
references: Conserv Biol. 2007 Oct;21(5):1269-79
references: 17883492
references: Annu Rev Genet. 1998;32:415-35
references: 9928486
references: J Mol Evol. 2008 Apr;66(4):384-94
references: 18347751
references: J Evol Biol. 2011 Jan;24(1):184-95
references: 21091566
references: Trends Ecol Evol. 1988 Oct;3(10):254-9
references: 21227241
references: Nat Rev Genet. 2010 Jan;11(1):17-30
references: 19953080
references: Proc Biol Sci. 1997 Dec 22;264(1389):1813-9
references: 9447738
references: Nature. 1993 Jul 1;364(6432):33-9
references: 8316295
references: Evolution. 2003 Aug;57(8):1707-22
references: 14503614
references: Proc Biol Sci. 2010 Apr 7;277(1684):979-88
references: 20071384
references: BMC Evol Biol. 2009 Apr 12;9:73
references: 19361342
references: Proc Natl Acad Sci U S A. 2005 Mar 22;102(12):4414-8
references: 15755811
references: Mol Biol Evol. 2005 May;22(5):1208-22
references: 15703242
references: Mol Biol Evol. 2011 Oct;28(10):2731-9
references: 21546353
references: J Evol Biol. 2003 May;16(3):363-77
references: 14635837
references: J Evol Biol. 2008 Jan;21(1):213-225
references: 18021201
references: Heredity (Edinb). 2001 Apr;86(Pt 4):439-50
references: 11520344
references: Genet Res. 2007 Dec;89(5-6):491-503
references: 18976539
references: Mol Biol Evol. 1986 Sep;3(5):418-26
references: 3444411
references: Nature. 1981 Sep 3;293(5827):55-7
references: 7266658
references: Anim Reprod Sci. 2009 Aug;114(1-3):269-78
references: 18980814
references: Proc Natl Acad Sci U S A. 2004 Mar 9;101(10):3490-4
references: 14990802
references: Ecol Evol. 2013 Jun;3(6):1552-68
references: 23789067
references: Proc Biol Sci. 1997 Oct 22;264(1387):1471-9
references: 9364787
references: Tissue Antigens. 2011 Feb;77(2):118-25
references: 21214524
references: Science. 1982 Oct 22;218(4570):384-7
references: 7123238
references: Proc Natl Acad Sci U S A. 2005 Apr 12;102(15):5460-5
references: 15784743
references: J Evol Biol. 2008 Jul;21(4):1144-50
references: 18462313
references: Bioessays. 2010 Nov;32(11):940-8
references: 20827785
references: Biol Rev Camb Philos Soc. 2007 Nov;82(4):591-605
references: 17944619
references: Trends Ecol Evol. 1990 Jun;5(6):181-7
references: 21232350
references: Genetics. 1992 Oct;132(2):575-81
references: 1427044
references: Bioinformatics. 2004 Jan 22;20(2):289-90
references: 14734327
references: Mol Ecol. 2000 Aug;9(8):1013-27
references: 10964221
references: Mol Ecol. 2009 Aug;18(15):3121-3
references: 19682244
references: Parasitol Today. 1995 Aug;11(8):306-10
references: 15275331
references: Nucleic Acids Res. 2004 Mar 19;32(5):1792-7
references: 15034147
references: Immunol Rev. 1999 Feb;167:169-78
references: 10319259
references: Genome Biol. 2004;5(7):R47
references: 15239832
references: Immunogenetics. 1992;36(3):135-48
references: 1612648
references: Nature. 2002 Dec 5;420(6915):520-62
references: 12466850
references: Am Nat. 2003 Nov;162(5):597-614
references: 14618538