This study provides evidence of fine-grained genetic structuring in Mediterranean mussels (Mytilus galloprovincialis) from the Strait of Istanbul, caused by barriers to gene flow via contaminant-mediated selection. In this study, mitochondrial D-loop sequences were analyzed in mussels from 8 localities, all less than 30 kilometers apart, with differing contaminant loads. The results were: 1) Intra-population genetic differentiation (Φ_ST) between sites with high and low contaminant loads was high (up to 0.459), even at distances of only a few kilometers. 2) Genetic diversity was negatively correlated with the contaminant load (“genetic erosion”). 3) There was evidence of selection, based on haplotype frequencies and neutrality tests (Tajima’s D), with purifying selection at the most contaminated site and balancing selection at the least contaminated. 4) Genetic distance was not correlated with geographic distance (no isolation-by-distance), but was correlated with contaminant load at each site. 5) Population dendrograms and Bayesian estimators of migration indicated that gene flow between sites was affected by contamination. For the dendrograms of the sampling sites, the clades clustered according to contaminant load more than geographic distance. Overall, these results suggest that 1) contamination may serve as a genotype-dependent dispersal barrier (i.e., contamination may not affect total number of migrants, just the relative proportions of the haplotypes in the established immigrants), leading strong population differentiation over short distances, and 2) genetic erosion may occur by a combination of selection and altered patterns of haplotype-specific gene flow. These effects may be more pronounced in the Strait of Istanbul than in other locations because of the riverine nature and strong, uni-directional current of the strait.

这项研究提供了来自伊斯坦布尔海峡的地中海贻贝（ Mytilus galloprovincialis ）细粒度遗传结构的证据，该结构是由污染物介导的选择对基因流动的障碍造成的。在这项研究中，对来自 8 个地点的贻贝的线粒体 D 环序列进行了分析，这些地点相距不到 30 公里，污染物负荷不同。结果是： 1)即使距离只有几公里，污染物负荷高和低的地点之间的群体内遗传分化 (Φ _{ST ) 也很高（高达 0.459）。}2）遗传多样性与污染物负荷（“遗传侵蚀”）呈负相关。3）有选择的证据，基于单倍型频率和中性测试（Tajima's D），在污染最严重的地点进行净化选择，在污染最轻的地点进行平衡选择。4）遗传距离与地理距离无关（无距离隔离），但与每个地点的污染物负荷相关。5) 种群树状图和迁移的贝叶斯估计量表明位点之间的基因流动受到污染的影响。对于采样点的树状图，进化枝根据污染物含量而不是地理距离进行聚类。总体而言，这些结果表明：1）污染可能作为基因型依赖性扩散屏障（即污染可能不会影响移民总数，只影响已建立的移民中单倍型的相对比例），导致短距离内的强烈种群分化，2) 遗传侵蚀可能是通过选择和单倍型特异性基因流模式改变的结合而发生的。由于伊斯坦布尔海峡的河流性质和强大的单向水流，这些影响在伊斯坦布尔海峡可能比其他地方更为明显。