怒江扎那纹胸鮡的遗传多样性和遗传分化

怒江水电开发将对扎那纹胸鮡产生不利的影响。为了解扎那纹胸鮡遗传多样性和遗传分化情况,文章测定了采自怒江中下游怒江州地区的贡山、古登和泸水及保山市地区的道街、勐糯和木城6个扎那纹胸鮡群体共102个个体的线粒体Cyt b基因序列。结果显示,在1137bp序列中共检测到87个变异位点,定义了36个单元型。总样品的单元型多样性(h)和核苷酸多样性(π)分别为0.851±0.028和0.01356±0.0008。扎那纹胸鮡的遗传多样性相对较低,但怒江州种群遗传多样性显著高于保山市种群。群体间分化指数(FST)(0.475~0.846)明显高于群体内分化指数(0.002~0.108),且各群体间分化指数和地理距离呈线性正相关。利用AMOVA(Analysis of molecular variance)对遗传分化进行分割,群体间和群体内分别占53.65%和46.35%,群体间遗传分化指数(FST)为0.5365(P0.01),扎那纹胸鮡在怒江州和保山种群分化显著。单元型分子系统树和简约网络图显示,扎那纹胸鮡单元型聚为两个独立的支系:怒江州支系和保山市支系。这些鱼类至少代表一个管理单位,但也可能是一个进化显著单位。因此,建议保护扎那纹胸鮡种群,在水电工程建设时应充分考虑扎那纹胸鮡种群结构现状,避免不同区域的种群之间发生基因交流。

Genetic diversity and differentiation between populations of Glyptothorax zanaensis in the middle and lower reaches of the Nujiang River

The development of hydroelectricity in the Nujiang River would have adverse impacts on the populations of Glyptothorax zanaensis. In order to assess the genetic diversity and differentiation of this species, we sequenced the cytochrome b gene of the mitochondria in 102 individuals of the fish collected from 6 sampling sites (Gongshan, Gudeng and Lushui in the Nujiang Prefectural District and Daojie, Mengnuo and Mucheng in the Baoshan Municipal District). A total of 87 variation sites were detected in the fragment of 1 137 bp in length, with which the 102 samples were defined as 36 haplotypes. The haplotype diversity (h) and the nucleotide diversity (π) of total samples were 0.851±0.028 and 0.01356±0.0008, respectively. Therefore, the genetic diversity of G. zanaensis was relatively low. However, the genetic diversity of the Nujiang population was significantly higher than that of the Baoshan population. The pairwise F_st value between the populations (0.475–0.846) was higher than that within the population (0.002–0.108), which implied that the F_st value was positively related to geographic distance. Analysis of molecular variance (AMOVA) showed that the genetic differentiation between the populations and within the populations were 53.65% and 46.35%, respectively. The fixation index (F_st value) was 0.5365, indicating that there existed significant differentiation between the Nujiang population and the Baoshan population. The phylogentic tree and networks of the haplotypes of G. zanaensis showed that there were two separate lineages: the Nujiang lineage and the Baoshan lineage. Each lineage represents at least one separated management unit, or belongs to an evolutionary significant unit. It was suggested that in the construction of hydroelectric projects the measures for protecting G. zanaensis should be adopted in fully considering the populations of G. zanaensis and the status quo of their population structure to avoid the occurrence of gene exchange among populations.