额尔齐斯河2种类型雌性银鲫的形态特征及D-loop基因序列比较

2008年5月调查发现,在额尔齐斯河主河道(185团)的雌性银鲫(Carassius auratus gibelio)群体中存在2种形态类型,按照体长比体高的形态学性状区分,分别为高背型(1.78~2.14)和低背型(2.18~2.39)。形态学分析表明,高背型和低背型的侧线鳞分别为31和30,侧线上(下)鳞为分别7和6,两者在体高、头高、尾柄高、体宽、头宽等性状上存在显著差异(P<0.01),高背型比低背型具有明显的体型优势。生长特性分析表明,在相同体长或年龄的雌性群体中,高背型的平均体质量约为低背型的1.3~1.9倍,而表现出更为优越的生长性能。线粒体控制区序列分析表明,高背型和低背型群体各自独享1个单倍型(分别为EG1和ED1),为2个不同的遗传谱系类群,遗传分化仅为0.004,远低于属内种间的0.020~0.045,两者尚属群体内变异;在分子系统关系中,高背型和低背型分别与方正银鲫的2个单倍型(FZ1和FZ13)共享并聚为单系,推测额尔齐斯河银鲫源自于黑龙江(方正银鲫)。与国内其他地方群体或品种比较表明,额尔齐斯河2种类型雌性银鲫,特别是高背型具有更为突出的生长优势,可作为优良的开发养殖品种和更具潜力的鱼类育种材料。

Comparative analysis between two types of female silver crucian carp Carassius auratus gibelio in the Irtysh River using morphology and mitochondrial control regions

Two types of female silver crucian carp Carassius auratus gibelio were discovered in the main stem of the Irtysh Rive (the Crop 185) in May 2008. We defined them as high-dorsal silver crucian carp (1.78-2.14) and low-dorsal silver crucian carp (2.18-2.39) based on differences in their morphology (body length/body depth). The number of lateral line scales in the high and low-dorsal silver crucian carp is 31 and 30, respectively. The number of scales above (or below) the lateral line is 7 (6), the number of scales above (or below) the lateral line in the caudal peduncle is 3 (2). High-dorsal silver crucian carp exhibit a size advantage based on the significant difference in body depth and width, head depth and width, and caudal peduncle depth (P<0.01) between high and low-dorsal silver crucian carp. The mean weight of high-dorsal silver crucian carp is 1.3-1.9 times that of low-dorsal silver crucian carp. A comparison of the mitochondrial control region sequences of the two types revealed that each has one haplotype, thus representing intraspecific variation with a low genetic diversity value (0.004). The two types and Fangzheng silver crucian carp in the Heilongjiang River are monophylic, and share the same haplotype with Fangzheng silver crucian carp. Accordingly, we speculate that the Irtysh silver crucian carps are derived from the Heilongjiang River basin. Our observations suggest the two types of C. a. gibelio, particularly the high-dorsal silver crucian carp, have a growth advantage over other crucian carps. Given this, they offer greater potential as breeding stock. Our results provide a theoretical basis for better conservation and utilization of the unique varieties of Irtysh River silver crucian carp.