DNA barcoding of a tropical anguillid eel, Anguilla bicolor (Actinopterygii: Anguilliformes), in Indo-Pacific region and notes on its population structure

ABSTRACT The tropical anguillid eel, Anguilla bicolor McCelland, 1844, includes two subspecies, Anguilla bicolor bicolor McCelland, 1844 and Anguilla bicolor pacifica Schmidt, 1928, and is distributed across the Indo-Pacific region. Although A. bicolor is widely distributed and recognized as an important fish resource in the Indo-Pacific region, few studies have been conducted on its genetic variation and population structure. DNA barcoding of A. bicolor specimens collected in the Indo-Pacific region was carried out in this study using mitochondrial cytochrome c oxidase subunit I. Anguilla bicolor was found to diverge genetically, which supported its classification into two different subspecies. In addition, our study showed that A. bicolor bicolor had two genetically distinct populations/groups, and these different populations co-occur geographically in Indonesia and Malaysia in the eastern Indian Ocean. Our findings suggest that the eel larvae might be transported from at least two geographically different spawning grounds in the Indian Ocean, and then recruited to and settled in the same habitats in Indonesian and Malaysian waters. The molecular evidence calls for further research on the life history, stock assessment and protection of the populations of A. bicolor bicolor in Indonesia and Malaysia.摘要 1844年由McClelland命名的热带双色鳗鲡（Anguilla bicolor McClelland, 1844）包含两个亚种：1844年命名的双色鳗鲡指名亚种（Anguilla bicolor bicolor McClelland, 1844）与1928年由Schmidt命名的双色鳗鲡太平洋亚种（Anguilla bicolor pacifica Schmidt, 1928），其分布范围覆盖印度-太平洋海域。尽管双色鳗鲡分布广泛，且被视为印度-太平洋地区重要的渔业资源，但针对其遗传变异与种群结构的研究仍较为匮乏。本研究针对印度-太平洋海域采集的双色鳗鲡标本，采用线粒体细胞色素c氧化酶亚基I（mitochondrial cytochrome c oxidase subunit I）开展DNA条形码（DNA barcoding）分析。结果显示，双色鳗鲡存在遗传分化，这一结果支持将其划分为两个独立亚种的分类观点。此外，本研究发现双色鳗鲡指名亚种存在两个遗传分化显著的种群/类群，且这些不同种群在东印度洋的印度尼西亚与马来西亚海域呈现地理同域分布。本研究结果表明，该鳗鲡幼体可能源自印度洋至少两处地理隔离的产卵场，随后被输送并定居于印度尼西亚与马来西亚海域的相同栖息地。本研究提供的分子生物学证据，呼吁针对印度尼西亚及马来西亚海域双色鳗鲡指名亚种的生活史、资源评估与种群保护开展进一步研究。