A single genomic region involving a putative chromosome rearrangement in flat oyster (Ostrea edulis) is associated with differential host resilience to the parasite Bonamia ostreae

European flat oyster (Ostrea edulis) is an ecologically and economically important marine bivalve, that has been severely affected by the intracellular parasite Bonamia ostreae. In this study, a flat oyster SNP array (~14,000 SNPs) was used to validate previously reported outlier loci for divergent selection associated with B. ostreae exposure in the Northeast Atlantic Area. A total of 134 wild and hatchery individuals from the North Sea, collected in naïve (NV) and long-term affected (LTA) areas, were analysed. Genetic diversity and differentiation were related to the sampling origin (wild vs hatchery) when using neutral markers, and to bonamiosis status (NV vs LTA) when using outlier loci for divergent selection. Two genetic clusters appeared intermingled in all sampling locations when using outlier loci and their frequency was associated with their bonamiosis status. When both clusters were compared, outlier datasets showed high genetic divergence (FST > 0.25) unlike neutral loci ...欧洲扁牡蛎（Ostrea edulis）是兼具生态与经济重要性的海洋双壳类动物，曾遭受胞内寄生虫牡蛎包拉米虫（Bonamia ostreae）的严重侵害。本研究采用一款包含约14000个单核苷酸多态性（single nucleotide polymorphism, SNP）的扁牡蛎SNP芯片，对东北大西洋海域中此前报道的、与牡蛎包拉米虫暴露相关的歧化选择离群位点进行验证。研究共分析了采自北海未暴露（naïve, NV）与长期受感染（long-term affected, LTA）区域的134份野生及育苗场个体样本。借助中性标记开展分析时，遗传多样性与遗传分化与采样来源（野生 vs 育苗场）相关；而使用歧化选择离群位点分析时，则与包拉米虫病感染状态（NV vs LTA）相关。当采用离群位点进行分析时，所有采样区域均出现两种相互混杂的遗传聚类簇，且其频率与包拉米虫病感染状态相关。对这两类聚类簇进行比较时，离群位点数据集展现出极高的遗传分化水平（固定指数FST > 0.25），这与中性标记的分析结果截然不同。