title: Selection on MHC class II supertypes in the New Zealand endemic Hochstetter's frog.
abstract: BACKGROUND
  The New Zealand native frogs, family Leiopelmatidae, are among the most archaic in the world. Leiopelma hochstetteri (Hochstetter's frog) is a small, semi-aquatic frog with numerous, fragmented populations scattered across New Zealand's North Island. We characterized a major histocompatibility complex (MHC) class II B gene (DAB) in L. hochstetteri from a spleen transcriptome, and then compared its diversity to neutral microsatellite markers to assess the adaptive genetic diversity of five populations ("evolutionarily significant units", ESUs).
  
  
  RESULTS
  L. hochstetteri possessed very high MHC diversity, with 74 DAB alleles characterized. Extremely high differentiation was observed at the DAB locus, with only two alleles shared between populations, a pattern that was not reflected in the microsatellites. Clustering analysis on putative peptide binding residues of the DAB alleles indicated four functional supertypes, all of which were represented in 4 of 5 populations, albeit at different frequencies. Otawa was an exception to these observations, with only two DAB alleles present.
  
  
  CONCLUSIONS
  This study of MHC diversity highlights extreme population differentiation at this functional locus. Supertype differentiation was high among populations, suggesting spatial and/or temporal variation in selection pressures. Low DAB diversity in Otawa may limit this population's adaptive potential to future pathogenic challenges.
authors.affiliation: Faculty of Veterinary Science, University of Sydney, Sydney, Australia. mette.lillie@sydney.edu.au.
authors.forename: Mette
authors.initials: M
authors.lastname: Lillie
authors.affiliation: Faculty of Veterinary Science, University of Sydney, Sydney, Australia. catherine.grueber@sydney.edu.au.|San Diego Zoo Global, San Diego, USA. catherine.grueber@sydney.edu.au.
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Grueber
authors.affiliation: Department of Biology, University of Hawai'i at Mānoa, Honolulu, USA. jolene.sutton@gmail.com.
authors.forename: Jolene T
authors.initials: JT
authors.lastname: Sutton
authors.affiliation: Landcare Research, Auckland, New Zealand. howittr@landcareresearch.co.nz.
authors.forename: Robyn
authors.initials: R
authors.lastname: Howitt
authors.affiliation: Department of Biology, University of Otago, Dunedin, New Zealand. phil.bishop@otago.ac.nz.
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Bishop
authors.affiliation: Landcare Research, Auckland, New Zealand. Dianne.Gleeson@canberra.edu.au.|Institute for Applied Ecology, University of Canberra, Bruce, Australia. Dianne.Gleeson@canberra.edu.au.
authors.forename: Dianne
authors.initials: D
authors.lastname: Gleeson
authors.affiliation: Faculty of Veterinary Science, University of Sydney, Sydney, Australia. kathy.belov@sydney.edu.au.
authors.forename: Katherine
authors.initials: K
authors.lastname: Belov
mesh_terms: D000595:Amino Acid Sequence; D029845:Amphibian Proteins / Q000235:genetics*; D000818:Animals; D001001:Anura / Q000235:genetics* / Q000276:immunology*; D056727:Endangered Species; D014644:Genetic Variation; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D009520:New Zealand; D016415:Sequence Alignment
chemical_list: D029845:Amphibian Proteins; D000949:Histocompatibility Antigens Class II