我国近海星康吉鳗群体的形态学、遗传学比较研究

结合形态学、遗传学的方法,分别对青岛近海(黄海)、舟山近海(东海)的星康吉鳗群体做了相关系统的研究。通过单因素方差分析、判别分析、主成分分析方法对两个星康吉鳗地理群体的9个可量性状进行形态学比较研究;基于线粒体DNA (mtDNA)序列进行遗传学分析研究。形态学研究结果显示,舟山海域的星康吉鳗肌肉中含有"I"形硬肌间骨,青岛海域星康吉鳗的肌肉中无硬肌间骨;单因素方差分析结果显示,两个群体的7个可量指标:肛长、头宽、吻长、口裂长、眼径长、背鳍前长和胸鳍长存在显著差异;在主成分分析中,基于前两个主成分绘制的散点图基本能够将两个星康吉鳗群体区分开来;判别分析结果显示,青岛、舟山两群体的判别准确率分别为100%和94.7%。3种多元统计分析结果均表明青岛、舟山两个星康吉鳗群体在外部形态上存在一定程度差异,但根据75%识别与划分规则,认为两组群体的形态学差异尚未达到亚种水平。遗传学研究表明,在所检测的mtDNA水平上两个星康吉鳗群体遗传多样性无明显差异,邻接系统发育树未呈现明显的谱系关系,遗传分化指数FST也显示两群体遗传差异小,遗传分化不显著,属同一种群。

Comparison of morphological and genetic characteristics of Conger myriaster populations in China

Conger myriaster is a commercially important species in China. The population structure of C. myriaster remains a mystery and the spawning activities of C. myriaster are not well known because larvae and adults of this species have separate habitats and its spawning grounds have not been discovered. Several hypotheses on the population structure and spawning grounds of C. myriaster have been proposed. Takai described that this species has a single population with a single spawning site. On the other hand, there are also some indications of the possibility of multiple spawning populations. So it is important to clarify the population structure of C. myriaster to provide basics for future detailed examination on its life history. If this species has multiple populations, there may be some morphological and genetic differences in the samples collected from different sea areas at the same time. In the present study, we combined morphological and genetic methods to understand the morphological and genetic differences of C. myriaster in the two different localities of Zhoushan (East China Sea) and Qingdao (Yellow Sea). The morphological studies were conducted by using one-way ANOVA, discriminant analysis and principal component analysis. Genetic analysis of the mitochondrial DNA (mtDNA) sequence was carried out. Results from morphological studies indicated that there were intermuscular bones of "I" type in the muscle of the C. myriaster from Zhoushan group but not in Qingdao group. The results of multivariate statistical analysis showed that there were significant differences in seven morphological measurements (preanal length, head width, snout length, rictus length, eye diameter, predorsal length) of C. myriaster from different groups, and these measurements were all over the body. In principal component analysis, C. myriaster from different groups could be distinguished by a scatter plot based on the first two principal components. Discriminant analysis results showed that the correct diserimi-nation rates of Qingdao and Zhoushan groups were 100% and 94.7%, respectively. The results of multivariate statistical analysis methods showed that there were significant differences in morphology between the two groups. But according to the Mayr''s 75% rule, most differences in morphology between the two groups were characterized under-subspecies. Genetic results suggested that there was no significant difference in genetic diversity between samples collected from different locations on the level of mtDNA. The neighbor-joining tree showed no genealogical clade. The pairwise fixation index F_ST revealed no significant genetic difference between the two groups. The present study provides morphological and genetic basis for the taxonomic status of the C. myriaster population in China. It also provides useful information for the population assessment, management and conservation of C. myriaster.