基于颌骨长度和线粒体Cytb序列变异探讨短颌鲚的分类地位  

Taxonomy of shortjaw tapertail anchovy Coilia brachygnathus by jaw length and mitochondrial Cytochrome b gene analysis

作　　者：许志强[1] 葛家春[1] 黄成[2] 窦红霞[2] 潘建林[1] 夏爱军[1] 

机构地区：[1]江苏省淡水水产研究所,江苏南京210017 [2]南京大学生命科学学院,江苏南京210093

出　　处：《大连水产学院学报》2009年第3期242-246,共5页Journal of Dalian Fisheries University

基　　金：江苏省六大人才高峰项目(07-G-028);江苏省水产三项工程项目(K-2006-3);江苏省科研条件与设备专项(BM2006503)

摘　　要：鲚属Coilia鱼类外形十分相似,该属刀鲚C.nasus、短颌鲚C.brachygnathus的分类问题一直存在较大争议。通过分析比较长江流域刀鲚、短颌鲚的纵列鳞数、臀鳍数、幽门盲囊数以及颌骨长度的变异情况,结合线粒体DNA Cyt b序列分析,研究了短颌鲚的分类地位。结果表明:虽然纵列鳞数、臀鳍数、幽门盲囊数等特征在刀鲚与短颌鲚的区分上有一定的倾向,但重叠较大,难以截然分开。对110尾刀鲚、40尾短颌鲚以及36尾定居型刀鲚——湖鲚C.nasus taihuensis的上颌骨长度进行测量,与刀鲚的上颌骨长度/头长(1.125±0.091)相比,湖鲚、短颌鲚的上颌骨长度/头长(1.022±0.045、0.981±0.095)均有所降低,其中刀鲚、短颌鲚的上颌骨长度/头长变异系数较大(8.01%和9.77%),而湖鲚的最小(4.55%)。三者的上颌骨长度/头长变异范围存在一定的交叉,表明鲚属鱼类上颌骨长度不是一种稳定的特征,推测其受生态环境、生活习性影响较大,不能作为判定物种有效性的主要依据。用PCR产物直接测序法测定了刀鲚、短颌鲚、湖鲚、凤鲚的mtDNACyt b基因序列,刀鲚与短颌鲚间的平均遗传距离为0.002,刀鲚与湖鲚间的遗传距离为0.003,而湖鲚与短颌鲚之间的遗传距离仅为0.001。以鳀科鳀属的Engraulis encrasicolus和E.japonicus为外群,用NJ法、ML法以及MP法进行系统发生分析,结果表明:凤鲚C.mystus分化较早,推测其在进化上处于比较原始的地位,而刀鲚、短颌鲚与湖鲚之间构成多岐分枝,三者之间不能明确区分。综合颌骨长度变异以及mtDNA Cyt b序列分析,认为短颌鲚和湖鲚一样,属于刀鲚在长江的一个淡水生态型种群,而非一个独立的物种。There has still been controversy in taxonomic relationship between Coilia nasus and C. brachygnathus due to similarity in morphology among anchovy Coilia. Thus, the numbers of longitudinal scales, anal pyloric caeca, and variation in the maxillary bone length were measured in 110 samples of C. nasus ,40 fin-rays, samples of C. barchygnathus and 36 samples of C. nasus taihuensis. The taxonomic status of the C. brachygnathus was discussed along with the analysis of the Cyt b sequencing of the mitochondria DNA. C. nasus taihuensis and C. brachygnathus had a relative lower ratio of maxillary bone length to head length （1. 125±0.091 vs 1. 022±0. 045 and 0.981±0. 095 ） and larger variation coefficient （8.01% and 9.77% vs 4.55% ） compared with C. nasus. Therefore, we deduced that the maxillary bone length of the anchovy Coilia might be deeply influenced by the environment and the life habit. So the maxillary bone length might not be treated as a main standard for the validity of diputed species in Coilia genus. The mitochondria DNA Cyt b sequences of the four species anchovy Coilia were direct sequenced and submitted to GeneBank. The average genetic distance between C. nasus and C. brachygnathus was 0.002, less than that between the C. nasus and C. nasus taihuensis while the average genetic distance between C. nasus taihuensis and C. brachygnathus was 0.001. Neighbor - Joining （ NJ）, Maximum likelihood （ML） and Maximum - Parsimony （MP） were employed to reconstruct the phylogeny with Engraulis encrasicolus and E. japonicus designated as outgroup. C. mystus has a basal position, suggesting that the species are more primitive than the other three Coilia in the evolution. C. nasus, C. brachygnathus and C. nasus taihuensis failed to form monophyletie class and could not be separated clearly. As good as C. nasus taihuensis, C. brachygnathus should be considered as different ecotypes of C. nasus other than a valid species separately in the freshwater.

关 键 词：刀鲚 短颌鲚 颌骨长度 CYTB 

分 类 号：Q959.46[生物学—动物学] S917.4[农业科学—水产科学]