Parallel signatures of selection at genomic islands of divergence and the major histocompatibility complex in ecotypes of sockeye salmon across Alaska

Understanding the genetic mechanisms that facilitate adaptive radiation is an important component of evolutionary biology. Here, we genotyped 82 neutral SNPs, seven SNPs in islands of divergence identified in a previous study (island SNPs), and a region of the major histocompatibility complex (MHC) in 32 populations of sockeye salmon to investigate whether conserved genes and genomic regions are involved in adaptive radiation. Populations representing three ecotypes were sampled from seven drainages with differing habitats and colonization histories spanning a range of 2,000 km. We found strong signatures of parallel selection across drainages at the island SNPs and MHC, suggesting that the same loci undergo divergent selection during adaptive radiation. However, patterns of differentiation at most island SNPs and the MHC were not associated with ecotypes, suggesting that these loci are responding differently to a mosaic of selective pressures. Our study provides some of the first e...

阐明促进适应性辐射（adaptive radiation）的遗传机制，是进化生物学研究的重要组成部分。
本研究对32个红大麻哈鱼（sockeye salmon）种群开展基因分型检测，涵盖82个中性单核苷酸多态性（Single Nucleotide Polymorphism, SNP）、既往研究中鉴定出的分化岛（islands of divergence）区域内的7个SNP（以下简称分化岛SNP），以及一段主要组织相容性复合体（major histocompatibility complex, MHC）序列，旨在探究保守基因与基因组区域是否参与适应性辐射过程。研究从覆盖2000公里范围、生境与定殖历史各异的7个水系中采集了代表3种生态型（ecotypes）的种群样本。
我们在分化岛SNP与MHC区域中检测到了跨水系的强平行选择（parallel selection）信号，表明在适应性辐射过程中，相同的基因座（loci）经历了趋异选择（divergent selection）。
然而，多数分化岛SNP与MHC区域的分化模式与生态型并无关联，提示这些基因座对镶嵌式选择压力（mosaic of selective pressures）的响应模式存在差异。
本研究提供了适应性辐射研究领域的首批（部分）e...