赤水河外来鱼类尖[鱼岁]和董氏须鳅的引种溯源及生态适应性分析

Analysis of Introduction Source and Ecological Adaptability of Exotic Fishes Rhynchocypris oxycephalus and Barbatula toni in Chishui River

历史上,赤水河流域干流及支流的鱼类物种组成中未曾出现过尖头[鱼岁](Rhynchocypris oxycephalus)和董氏须鳅(Barbatula toni)。但是,近年来在赤水河支流白沙河的鱼类资源调查中发现了这两个物种的分布,其来源及未来的生存可能性受到关注。本研究比较了尖头[鱼岁]赤水河野外种群与养殖种群形态上的差异;基于线粒体Cyt b基因序列,分析了赤水河流域尖头[鱼岁]和董氏须鳅的来源,并通过生态位模型分析了这两种鱼在赤水河流域的生态适应性。形态数据结果表明,尖头[鱼岁]在赤水河的野外种群与养殖种群的个体大小存在显著差异,养殖种群的体长、尾柄长、尾柄高3个形态数据均高于野外种群。分子系统发育分析结果显示,尖头[鱼岁]赤水河流域野外种群及养殖种群与辽宁杨运种群聚为一支,董氏须鳅则与来自内蒙古、辽宁和河北的种群聚为一支。生态位模型分析表明,赤水河支流白沙河具有尖头[鱼岁]的中度适生区,其适生性概率为0.620;而董氏须鳅在该区域的适生性概率较低,仅为0.025,这可能与该物种已有分布数据较少有关。采样中发现白沙河实际采样点的水温较低,与北方分布点的水温接近,推测该区域仍具备尖头[鱼岁]和董氏须鳅生存的条件。综上所述,赤水河流域的尖头[鱼岁]和董氏须鳅均为来自东北地区的外来种,且能适应赤水河的生态环境。这与现场访问结果一致,未来需要加强种群监测以防成为外来入侵种。

Rhynchocypris oxycephalus and Barbatula toni were not present in the Chishui River before. However, in recent years, both two species has be found in the Baisha River, a tributary of the Chishui River. Therefore, their sources and future survival possibilities should be paying more attention. We analyed their morphological characters and mitochondrial Cyt b gene sequences tracing where the two fish species R. oxycephalus and B. toni came from and built the ecological model to predict their ecological adaptability in the Chishui River. We got the the following results: 1) the individual size between wild and cultivated population was significantly different;2) three morphological characters got from the cultivated population are higher than those of the wild population. Based on Bayesian inferences, maximum likelihood and neighbor-joining methods for all haplotypes, phylogenetic analyses revealed that samples of R. oxycephalus from Chishui River including both cultivated and wild individuals firstly clustered with samples from Yangyun population Liaoning province, Northeast China(Fig. 2);samples of B. toni from Chishui River firstly clustered with those from Inner Mongolia, Liaoning and Hebei province(Fig. 3). Moreover, the results from the ecological niche model, MaxEnt, showed that the Baisha River, a tributary of the Chishui River, has a moderately suitable area for R. oxycephalus(the suitability probability was 0.620, Fig. 4), while the suitability probability for B. toni in this area was rather low(the suitability probability was 0.025), which with probably due to the little distribution information of this species(Fig. 4). The water temperature at the sampling site was relatively low, which was close to the water temperature of the northern sampling sites. It could be inferred that this area has suitable conditions for the survival of R. oxycephalus and B. toni. To sum up, these two exotic species in the Chishui River were from the northeastern of China, and adapted well to the local environment. This result was consistent with the survey of the local farmer. In the future, population monitoring needs to be strengthened to prevent them becoming invasive species.