Nonparallelism in MHCIIβ diversity accompanies nonparallelism in pathogen infection of lake whitefish (Coregonus clupeaformis) species pairs as revealed by next‐generation sequencing
Nonparallelism in MHCIIβ diversity accompanies nonparallelism in pathogen infection of lake whitefish (Coregonus clupeaformis) species pairs as revealed by next‐generation sequencing
复制标题
下一代测序揭示，MHCIIβ 多样性的非平行性伴随着湖白鱼 (Coregonus clupeaformis) 物种对病原体感染的非平行性
DOI：
10.1111/mec.12358
复制
发表时间：
2013
影响因子：
4.9
通讯作者：
L. Bernatchez
中科院分区：
文献类型：
--
作者：
S. Pavey;Maelle Sevellec;W. Adam;É. Normandeau;F. Lamaze;P. Gagnaire;M. Filteau;F. Hebert;Halim Maaroufi;L. Bernatchez
主要组织相容性 (MHC) 免疫系统基因可能会响应环境中的病原体而进化。因为它们也可能影响配偶选择，所以它们是在生态物种形成中具有重要意义的候选者。在这里，我们使用下一代测序来测试五个侏儒和正常白鲑同域对的 MHCIIβ 多样性和细菌感染模式的平行性一般假设。第二个目标是评估自然条件下特定 MHCIIβ 等位基因与病原体之间的功能关系。每个个体都有一到四个等位基因，表明有两个旁系同源基因座。在悬崖湖，矮化生态型对于最常见的等位基因是单态的。在韦伯斯特湖中，等位基因分布的偏向是朝向相同的等位基因，但在正常的生态型中，强调了湖泊之间的非平行分歧。我们的平衡选择信号在某些情况下与假定的肽结合区残基相匹配，但在其他情况下则不然，这支持了鱼类 MHCIIβ 与哺乳动物相比的重大功能差异的其他最新发现。等位基因较少的个体被感染的可能性较小；因此，我们没有发现杂合子优势假说的证据。 MHCIIβ等位基因和病原菌在多变量分析中形成不同的簇，并且某些等位基因的簇与病原体簇相关，或者有时与病原体的缺失相关，表明个体水平上的功能关系。鉴于矮化和正常白鱼对中 MHCIIβ 和细菌的模式不平行，我们得出结论，驱动 MHCIIβ 进化的病原体在其平行表型进化中并未发挥直接作用。
Major histocompatibility (MHC) immune system genes may evolve in response to pathogens in the environment. Because they also may affect mate choice, they are candidates for having great importance in ecological speciation. Here, we use next‐generation sequencing to test the general hypothesis of parallelism in patterns of MHCIIβ diversity and bacterial infections among five dwarf and normal whitefish sympatric pairs. A second objective was to assess the functional relationships between specific MHCIIβ alleles and pathogens in natural conditions. Each individual had between one and four alleles, indicating two paralogous loci. In Cliff Lake, the dwarf ecotype was monomorphic for the most common allele. In Webster Lake, the skew in the allelic distribution was towards the same allele but in the normal ecotype, underscoring the nonparallel divergence among lakes. Our signal of balancing selection matched putative peptide binding region residues in some cases, but not in others, supporting other recent findings of substantial functional differences in fish MHCIIβ compared with mammals. Individuals with fewer alleles were less likely to be infected; thus, we found no evidence for the heterozygote advantage hypothesis. MHCIIβ alleles and pathogenic bacteria formed distinct clusters in multivariate analyses, and clusters of certain alleles were associated with clusters of pathogens, or sometimes the absence of pathogens, indicating functional relationships at the individual level. Given that patterns of MHCIIβ and bacteria were nonparallel among dwarf and normal whitefish pairs, we conclude that pathogens driving MHCIIβ evolution did not play a direct role in their parallel phenotypic evolution.