Phylogeographic structure and historical demography of tarakihi (<i>Nemadactylus macropterus</i>) and king tarakihi (<i>Nemadactylus</i> n.sp.) in New Zealand

Tarakihi (Nemadactylus macropterus) is a demersal fish that supports valuable commercial, recreational, and customary fisheries in New Zealand. However, little is known about its stock structure. The population genetic structure, genetic diversity, and demographic history of N. macropterus were investigated using the hypervariable region one of the mitochondrial control region. 370 samples from 14 locations around New Zealand were collected. While weak genetic breaks were detected between Hawke’s Bay and East Northland and between the west and east coasts of South Island, no clear genetic structure was detected for the overall New Zealand area (ФST = 0.002, P = 0.18), indicative of a panmictic genetic structure. N. macropterus display a high level of genetic diversity and appear to have a historically large and stable population with a long evolutionary history. Bayesian skyline analysis indicates that the historic population has gone through two expansions, likely caused by repeated glacial cycles during the second half of the Pleistocene. The addition of 15 king tarakihi samples (Nemadactylus n.sp.) collected from the Three Kings Islands showed a clear genetic differentiation between the two morphotypes. These findings can inform the future management of N. macropterus and N. n.sp. to ensure a sustainable harvest.塔拉克希鱼（Nemadactylus macropterus）是一种底栖鱼类，支撑着新西兰极具价值的商业、休闲及传统渔业。目前学界对其种群结构的认知仍较为有限。本研究利用线粒体控制区（mitochondrial control region）的高变区I，对Nemadactylus macropterus的种群遗传结构、遗传多样性及种群历史动态展开了调查。研究共采集了新西兰周边14个采样点的370份样本。尽管在霍克斯湾（Hawke’s Bay）与北岛东部区域、南岛东西海岸之间检测到了微弱的遗传分化，但在新西兰全域范围内未发现显著的遗传结构（ФST=0.002，P=0.18），表明其种群具有随机交配型的遗传结构。Nemadactylus macropterus具有较高水平的遗传多样性，其历史种群规模庞大且稳定，演化历程悠久。贝叶斯天际线分析（Bayesian skyline analysis）结果显示，该物种的历史种群曾经历两次扩张事件，这大概率由更新世中后期反复出现的冰期循环所导致。本次研究补充纳入了从三王群岛（Three Kings Islands）采集的15份国王塔拉克希鱼（Nemadactylus n.sp.）样本，分析结果表明两种形态型之间存在显著的遗传分化。上述研究成果可为Nemadactylus macropterus及Nemadactylus n.sp.的后续渔业管理提供科学依据，以保障渔业资源的可持续捕捞。