Abstract：
In order to determine the influence of geographical distance, depth, and Longhurstian province on bacterial community composition and compare it with the composition of photosynthetic micro-eukaryote communities, 382 samples from a depth-resolved latitudinal transect (51°S-47°N) from the epipelagic zone of the Atlantic ocean were analyzed by Illumina amplicon sequencing. In the upper 100 m of the ocean, community similarity decreased toward the equator for 6000 km, but subsequently increased again, reaching similarity values of 40-60% for samples that were separated by ~12,000 km, resulting in a U-shaped distance-decay curve. We conclude that adaptation to local conditions can override the linear distance-decay relationship in the upper epipelagial of the Atlantic Ocean which is apparently not restrained by barriers to dispersal, since the same taxa were shared between the most distant communities. The six Longhurstian provinces covered by the transect were comprised of distinct microbial communities; ~30% of variation in community composition could be explained by province. Bacterial communities belonging to the deeper layer of the epipelagic zone (140-200 m) lacked a distance-decay relationship altogether and showed little provincialism. Interestingly, those biogeographical patterns were consistently found for bacteria from three different size fractions of the plankton with different taxonomic composition, indicating conserved underlying mechanisms. Analysis of the chloroplast 16S rRNA gene sequences revealed that phytoplankton composition was strongly correlated with both free-living and particle associated bacterial community composition (R between 0.51 and 0.62, p < 0.002). The data show that biogeographical patterns commonly found in macroecology do not hold for marine bacterioplankton, most likely because dispersal and evolution occur at drastically different rates in bacteria.
摘要：
为了确定地理距离的影响,深度,研究了Longhurstian省的细菌群落组成，并将其与光合微真核生物群落组成进行了比较，通过Illumina扩增子测序分析了来自大西洋上层带的深度分辨纬度样带（51°S-47°N）的382个样品。在海洋的100米上，群落相似性向赤道下降了6000公里，但随后又增加了，对于间隔约12,000公里的样本，相似度值达到40-60%，产生U形的距离衰减曲线。我们得出的结论是，适应当地条件可以覆盖大西洋上表层的线性距离-衰减关系，这显然不受扩散障碍的限制，因为相同的类群在最遥远的社区之间共享。样带覆盖的六个Longhurstian省由不同的微生物群落组成；约30％的群落组成变化可以由省解释。属于上层带（140-200m）较深层的细菌群落完全缺乏距离衰减关系，几乎没有地方主义。有趣的是,这些生物地理模式是一致发现的细菌来自三个不同大小的部分的浮游生物具有不同的分类组成，表明保守的潜在机制。对叶绿体16SrRNA基因序列的分析表明，浮游植物的组成与自由生活和颗粒相关的细菌群落组成密切相关（R在0.51和0.62之间，p<0.002）。数据表明，宏观生态学中常见的生物地理模式不适用于海洋浮游细菌，很可能是因为细菌的扩散和进化速度截然不同。
