Data from: Hidden diversity and phylogeographic history provide conservation insights for the edible seaweed Sargassum fusiforme in the Northwest Pacific

Understanding the evolutionary processes that have created diversity and the genetic potential of species to adapt to environmental change is an important premise for biodiversity conservation. Herein, we used mitochondrial trnW-L and cox3 and plastid rbcL-S data sets to analyze population genetic variation and phylogeographic history of the brown alga Sargassum fusiforme, whose natural resource has been largely exterminated in the Asia-Northwest Pacific in the past decades. Phylogenetic trees and network analysis consistently revealed three major haplotype-groups (A, B and C) in S. fusiforme, with A and B distributed in the Japan-Pacific coast. Group C consisted of three sub-groups (C1, C2 and C3) which were distributed in the Sea of Japan, the Yellow-Bohai Sea and East China Sea, respectively. IMa analysis revealed that the three groups diverged approximately during the mid-Pleistocene (c. 756–1,224 ka). EBSP showed that groups A and B underwent relatively long-term stable population size despite a subsequent rapid demographic expansion. FST and AMOVA analysis detected low population-level genetic variation and high degrees of divergence between groups. These results are essential to understand how environmental shifts and evolutionary processes shaped diversity and distribution of coastal seaweeds, and provide additional insights for conserving and managing seaweed resources.

阐明驱动物种多样性形成的演化进程，以及物种适应环境变化的遗传潜力，是开展生物多样性保护的重要前提。本研究借助线粒体trnW-L、cox3基因与质体rbcL-S数据集，对过去数十年间西北太平洋亚洲海域天然资源遭受大规模破坏的褐藻羊栖菜（Sargassum fusiforme）的种群遗传变异与谱系地理学历史进行解析。系统发育树与网络分析均一致表明，羊栖菜可划分为A、B、C三个主要单倍型类群：类群A与类群B分布于日本太平洋沿岸；类群C包含C1、C2、C3三个亚类群，分别对应分布于日本海、黄渤海及东海海域。IMa分析结果显示，三个类群的分化时间大致处于更新世中期（约75.6万至122.4万年前）。扩展贝叶斯天际线图（EBSP）分析显示，尽管后续经历了快速的种群数量扩张，但类群A与类群B的种群规模长期处于相对稳定状态。FST遗传分化系数与分子方差分析（AMOVA）结果显示，类群间遗传分化程度较高，但种群水平的遗传变异水平较低。本研究结果有助于深入理解环境变迁与演化进程如何塑造沿海海藻的多样性与分布格局，同时为海藻资源的保护与管理提供了新的理论依据。