Diplonemea (diplonemids) is one of the most abundant and species-rich protist groups in marine environments; however, their community structures among local and seasonal samples have not yet been compared. In the present study, we analyzed four diplonemid community structures around the Izu Peninsula, Japan using barcode sequences amplified from environmental DNA. These sequences and the results of statistical analyses indicated that communities at the same site were more similar to each other than those in the same season. Environmental variables were also measured, and their influence on diplonemid community structures was examined. Salinity, electrical conductivity, and temperature, and their correlated variables, appeared to influence the structures of diplonemid communities, which was consistent with previous findings; however, since the results obtained did not reach statistical significance, further studies are required. A comparison of each diplonemid community indicated that some lineages were unique to specific samples, while others were consistently detected in all samples. Members of the latter type are cosmopolitan candidates and may be better adapted to the environments of the studied area. Future studies that focus on the more adaptive members will provide a more detailed understanding of the mechanisms by which diplonemids are widely distributed in marine environments and will facilitate their utilization as indicator organisms to monitor environmental changes.

中文翻译：

---

日本伊豆半岛周边双龙群落的结构比较。


Diplonemea (diplonemids) 是海洋环境中数量最多、物种最丰富的原生生物类群之一；然而，尚未对当地和季节性样本中的群落结构进行比较。在本研究中，我们使用从环境 DNA 中扩增的条形码序列分析了日本伊豆半岛周围的四个双线虫群落结构。这些序列和统计分析结果表明，同一地点的群落彼此比同一季节的群落更加相似。还测量了环境变量，并检查了它们对双氯脲群落结构的影响。盐度、电导率和温度及其相关变量似乎影响双螺酰胺群落的结构，这与之前的发现一致；然而，由于获得的结果未达到统计学显着性，因此需要进一步研究。对每个双线虫群落的比较表明，某些谱系是特定样品所独有的，而其他谱系在所有样品中都一致检测到。后一类型的成员是国际化的候选人，可能更好地适应所研究地区的环境。未来的研究重点关注更具适应性的成员，将更详细地了解双克隆动物在海洋环境中广泛分布的机制，并将促进它们作为指示生物来监测环境变化。