Data from: Choosy wolves? Heterozygote advantage but no evidence of MHC-based disassortative mating

A variety of nonrandom mate choice strategies, including disassortative mating, are used by vertebrate species to avoid inbreeding, maintain heterozygosity and increase fitness. Disassortative mating may be mediated by the major histocompatibility complex (MHC), an important gene cluster controlling immune responses to pathogens. We investigated the patterns of mate choice in 26 wild-living breeding pairs of gray wolf (Canis lupus) that were identified through noninvasive genetic methods and genotyped at 3 MHC class II and 12 autosomal microsatellite (STR) loci. We tested for deviations from random mating and evaluated the covariance of genetic variables at functional and STR markers with fitness proxies deduced from pedigree reconstructions. Results did not show evidences of MHC-based disassortative mating. Rather we found a higher peptide similarity between mates at MHC loci as compared with random expectations. Fitness values were positively correlated with heterozygosity of the breeders at both MHC and STR loci, whereas they decreased with relatedness at STRs. These findings may indicate fitness advantages for breeders that, while avoiding highly related mates, are more similar at the MHC and have high levels of heterozygosity overall. Such a pattern of MHC-assortative mating may reflect local coadaptation of the breeders, while a reduction in genetic diversity may be balanced by heterozygote advantages.

多种非随机交配策略（包括异型交配（disassortative mating））被脊椎动物用于规避近交、维持群体杂合性并提升个体适合度。异型交配可能由主要组织相容性复合体（MHC）介导——这是一类调控病原体免疫应答的重要基因簇。本研究针对26个通过非侵入性遗传方法鉴定的野外灰狼（Canis lupus）繁殖配对展开交配模式分析，并对其在3个MHC II类位点与12个常染色体微卫星（STR，短串联重复序列）位点完成基因分型。我们检验了种群是否偏离随机交配模式，并评估了功能遗传标记与STR标记的遗传变量，以及通过谱系重建推导得到的适合度替代指标间的协方差关系。研究结果未发现基于MHC的异型交配证据。相反，与随机交配的预期相比，配对个体在MHC位点上的肽段相似性更高。繁殖个体的适合度与其在MHC与STR位点上的杂合性均呈正相关，而适合度则随STR位点上的亲缘关系升高而降低。上述研究结果表明，繁殖个体若在避免与高度亲缘个体交配的同时，MHC位点相似性更高且整体杂合性水平较高，则可获得适合度优势。这种MHC选型交配模式可能反映了繁殖个体的局部共适应现象，而遗传多样性的降低可通过杂合子优势得到平衡。