Data from: A hypervariable mitochondrial protein coding sequence associated with geographical origin in a cosmopolitan bloom-forming alga, Heterosigma akashiwo

Geographic distributions of phytoplankton species can be defined by events on both evolutionary time and shorter scales, e.g., recent climate changes. Additionally, modern industrial activity, including the transport of live fish and spat for aquaculture and aquatic microorganisms in ship ballast water, may aid the spread of phytoplankton. Obtaining a reliable marker is key to gaining insight into the phylogeographic history of a species. Here, we report a hypervariable mitochondrial gene in the cosmopolitan bloom-forming alga, Heterosigma akashiwo. We compared the entire mitochondrial genome sequences of seven H. akashiwo strains from Japanese and North American coastal waters and identified a hypervariable segment. The region codes for a hypothetical protein with no defined function, and its variations between Japanese and North American isolates, were prominent, while the sequences were more conserved among Japanese strains and North American isolates. Comparison of the sequence in isolates obtained from different geographical points in the Northern Hemisphere revealed that the sequence variations largely correlated with latitude and longitude (i.e. Pacific/Atlantic oceans). Our results demonstrate the usefulness of the sequence in determining the phylogeographic history of H. akashiwo.

浮游植物物种的地理分布可由进化时间尺度与更短时间尺度下的事件共同决定，例如近期的气候变化。此外，现代工业活动——包括水产养殖所用活鱼及幼体的运输、船舶压载水中携带的水生微生物——可能促进浮游植物的扩散。获取可靠的分子标记，是解析物种系统地理（phylogeographic）历史的关键所在。本研究报道了广布性水华藻类赤潮异弯藻（Heterosigma akashiwo）中的一段高变线粒体基因。我们比对了采自日本及北美近岸海域的7株赤潮异弯藻的完整线粒体基因组序列，成功鉴定出一段高变区域。该区域编码一种功能尚未明确的假定蛋白（hypothetical protein）；日美分离株间的序列变异十分显著，而日本菌株内部与北美菌株内部的序列则更为保守。对北半球不同地理点位分离株的序列比对结果显示，序列变异与纬度、经度（即太平洋/大西洋海域分布）存在显著相关性。本研究结果证实了该序列在解析赤潮异弯藻系统地理历史方面的应用价值。