中国石爬鮡属鱼类的形态变异及物种有效性研究
MORPHOLOGICAL VARIATIONS AND SPECIES VALIDITY OF GENUS EUCHILOGLANIS (SILURIFORMES:SISORIDAE)IN CHINA
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摘要: 石爬(鱼兆)属鱼类的青石爬(鱼兆)和黄石爬(鱼兆)的物种界限一直不清楚.采用形态判别和线粒体16S rRNA基因序列分析相结合的方法,分别研究分析了青石爬(鱼兆)和黄石爬(鱼兆)的物种划分、地理分化及遗传多态性.结果表明:(1)区别青石爬(鱼兆)和黄石爬(鱼兆)的重要特征腹鳍起点至臀鳍起点的距离是否大于至鳃孔下角的距离,腹鳍相对位置,头部相对大小与上颌须的须状延长部分等相互之间有一定的相关性,但是在研究的样本中没有截然的界限,而是有较大的重叠,难以区分;(2)从地埋分布看,金沙江不同支流的样本在上述特征上有一定的区别,但是没有发现青衣江的样本与其他支流的样本有截然的界限和明显的地理变化规律;(3)548 bp序列中,检测出2个多态位点,多态位点的比例为0.365%;(4)青石爬(鱼兆)和黄石爬(鱼兆)间的遗传差异极小,平均遗传距离仅为0.075%;(5)石爬(鱼兆)属鱼类个体间也无明显差异,遗传距离为0-0.381%,平均为0.06%.因此石爬(鱼兆)属鱼类划分为一个种更为客观,黄石爬(鱼兆)为青石爬(鱼兆)的同物异名.Abstract: The delimitation between Euchiloglanis davidi and Euchiloglanis kishinouyei has not been clear all the time. In the present paper, we studied inter specific and intra specific variations of E.davidi and E.kishinouyei by principal component analysis and 548bp mtDNA 16S rRNA sequences analysis. 35 characters were measured and 34 among them were analyzed using multivariate morphometrics for 80 specimens of the genus Euchiloglanis.We amplified and sequenced the mtDNA 16S rRNA gene fragments in 10 individuals of Euchiloglanis. Sequences were read from one strand (L strand) and aligned using Clusta1X 1.8 program and SEAVIEW program. Pairwise sequence comparisons to determine the amount of variation were performed using MEGA 2.1. According to the results of principal component analysis and p distance,the species validties were evaluated. The results showed that: (1)the diagnostic characters between E. davidi and E.kishinouyei,such as anterior position of ventral fins, its origin being always nearer or not to lower angle of gill opening than to anal fin,maxillary barbells extending beyond or not to gill opening,were correlated. However, specimens could not be distinguished definitely according to these differences because of the overlap in characters;(2)there were differences among populations from different localities,but no definite correlation to the tributary of Jinshajiang River could be found;(3)the genetic distance was very small between E.davidi. and E.kishinouye,and it was only 0.075% on average;(4)Only 2 variation loci were detected and the mutation rate was 0.365%;(5)the genetic distance was also small among the genus Euchiloglanis, ranging from 0—0.381% and 0.069% on average.Based on these results, Euchiloglanis species in China is suggested as only one species,and E.kishinouyei is argued as a synonym of E.davidi.