DOI: 10.5061/dryad.7926
title: Data from: Putative causes and consequences of MHC variation within and between locally adapted stickleback demes

description: Genes of the major histocompatibility complex have been a source of
 considerable research interest, owing in large part to the growing body of
 evidence that they may be subject to both natural and sexual selection.
 However, much remains to be learned about the dynamics of MHC genes in
 subdivided populations, particularly those characterized by divergent
 ecological pressures. In this study, we attempt to disentangle the
 relative roles of both parasite-mediated selection, and MHC-mediated mate
 choice in an open estuarine system inhabited by two parapatric, adaptively
 divergent threespine stickleback (Gasterosteus aculeatus) demes. We
 sequenced the putative peptide binding region (PBR) of an estimated four
 Class IIβ loci from 127 individuals, identifying 329 sequence variants
 (276 translated amino acid sequences). Demes differed significantly based
 on the frequency of MHC distributions, and in the communities of helminth
 parasites infecting resident sticklebacks. Strong signatures of natural
 selection were inferred from analyses of codon substitutions, particularly
 in the derived (freshwater) rather than the ancestral (marine) deme.
 Relationships between parasite load and MHC diversity were indicative of
 balancing selection, but only within the freshwater deme. Signals of
 MHC-mediated mate choice were weak, and differed significantly between
 demes. Moreover, MHC-mediated mate choice was significantly influenced by
 environmental salinity, and appeared of secondary importance to tendencies
 towards assortative mating. We discuss the implications of these findings
 in respect to ecological adaptation and the potential demographic
 consequences of possible outcomes of MHC-mediated mate choice.
description: ind_seqsIndividual sequence data. Columns include the code used to define individuals in the datasets (Ind), the MHC sequence identifier (Seq.ID) and the GenBank accession numbers of the respective sequences (Accession).parasitesParasite data. Ind denontes the individual identifier. Deme and Pop denote the deme and site of origin, respectively, of each individual. SL denotes standard length, in mm, from snout to caudal peduncle. Wt denotes weight, in grams, and k denotes Fulton's condition factor. Parasite taxa follow: larval digeneans (Blk.Spt), gill copepods (Gill.Cop), monogenean (Monogen) and digenean (Digen) trematodes, nematodes (Nem), acanthocephalans (Acanth), cestodes (Cest), plerocercoids (Pler). Total parasite infection of each individual are described via the Shannon-Wiener diversity index (H) and total parasite load (Load). No.AA denotes the number of unique MHC peptides, inferred from sequence data. AA.Dist denotes the average intra-individual protein distance.matingMate-choice data. The Male and Female columns contain identifiers for individuals used in the trials. Pairing denotes whether a potential couple in a given trial belong to the same or different demes. Rep.Suc denotes which male mated with the female in a given trial, and Suc.Mate denotes whether the successful male was from the same deme as the female. M.Pop and F.Pop denote the site of origin of the male and female, respectively. Env denotes the salinity of the test environment. M.Env and F.Env denote whether the test environment was representative of the native salinity of the male and female, respectively. TL and SL denote total and standard length, in mm, of each meal. Wt denotes the weight, in grams, of each male; whereas k denotes condition factor. M.AA and F.AA denote the number of unique MHC peptides for each male and female, respectively. Shared.AA denotes the number of MHC peptides in common between a potential couple in a given trial. M.Uniq.AA denotes the number of MHC peptides a male posses which differ from the female in a given trial. Comb.AA denotes the total number of unique MHC peptides between a male and female in a given trial. M.AA.Dist denotes the average intra-individual protein distance of each male. Pair.AA.Dist denotes the average pair-wise protein distance between a potential couple in a given trial.