Population structure and recruitment mechanism of Conger myriaster larvae using otolith microsturucture and mitochondrial DNA sequences

根据采自宫崎县延冈（Nobeoka，野冈）的细头海鳗矢状耳石的生长增量，八代（熊本县），安治（香川县），清水（静冈县）和索马（福岛县）在1996年和1998年。所有标本均在变质带前识别出深部裂隙。在本研究中，该检查被称为“海岸前沿标记”，该标记可能是有用的基准研究的生长历史和补充机制的物种。对耳石的观察表明，仔鱼在119.5日龄时已进入近海水域，变态发生在110-210日龄。通过对16个幼斑星天牛（C. myriasterleptocephali）线粒体DNA序列的测定，分析了幼斑星天牛的种群结构，包括细胞色素B基因控制区的前半部分。对产自宫崎县的野冈的16个样本进行了包括细胞色素B基因到对照区前半部分在内的共591个核苷酸位点的测序，八代（熊本县）和索马（福岛县）。在控制区的396个核苷酸位点中，有31个（7.8%）变异，16种单倍型，核苷酸序列间的差异在0.25 ~ 4.55%之间，平均为1.88%，表明该物种线粒体DNA控制区具有高度变异性。用邻接法构建的系统发育树没有显示出明显的地理聚类。这一结果表明，目前的标本可能来自一个单一的群体。

The growth history and recruitment of Conger myriaster were studied, based on growth increments in sagittal otoliths of leptocephali collected from Nobeoka (Miyazaki Pref.), Yatsushiro (Kumamoto Pref.), Aji (Kagawa Pref.), Shimizu (Shizuoka Pref.) and Soma (Fukushima Pref.) in 1996 and in 1998. The deep check was recognized at before metamorphic zone from all specimen. The check was called the "Coastal front mark" in the present study and this mark may be useful as a bench mark in studying the growth history and recruitment mechanism of the species. Examination of otoliths showed that larvae has entered into coastal water at the age of 119.5 days, and metamorphosis occurred at 110-210 days. Hatching dates extended from September to January.Mitochondrial DNA sequences that include a part of the cytochrome b gene to the first half of the control region of 16 C.myriaster leptocephali were determined to evaluate the population structure of the species. A total of 591 nucleotide site, including cytochrome b gene to the first half of the control region, was sequenced from 16 specimens from Nobeoka (Miyazaki Pref.), Yatsushiro (Kumamoto Pref.) and Soma (Fukushima Pref.). Out of 396 nucleotide sites on the control region, 31 (7.8 %) variable, 16 haplotypes being found. Differences between nucleotide sequences ranged between 0.25 and 4.55% with average of 1.88 %, indicating that the control region of the mitochondrial DNA in the species is characterized be high variability. The phylogenetic tree constructed by the neighbor-joining method shows neither significant geographic clusters. This result indicate that the present specimen might come from a single population.