水蕨的生境及其遗传多样性分析

Analyses for Habitat and Genetic Diversity of Ceratopteris thalictroides in China

对分布在中国的24个现存水蕨种群和历史记载曾经分布但现已绝迹的22个水蕨种群原产地进行了广泛调查,发现绝迹种群所在地的原生境已遭到严重破坏,其水体pH值和电导率的平均值都高于现存种群所在地(p<0.05).结果表明水蕨的濒危与水生生境破坏和丧失密切相关.用inter-简单重复序列(ISSR)标记分析了13个水蕨种群遗传多样性.总的多态位点百分率(PPB)为65.19%.分子变异分析(AMOVA)表明种群间的遗传变异为33.91%.结果显示水蕨在物种水平具有一个中间水平的遗传多样性和种群间低的遗传变异.孢子扩散引起的高的基因流可能是导致水蕨种群间低的遗传变异的主要原因.

In this study, twenty-four present locations of Ceratopteris thalictroides populations and twenty-two locations where the species had been previously recorded but is now extinct were investigated in China. These sites of the extinct populations currently have higher water pH and conductivity values than the current sites of remaining populations. The results indicate that the geographic distribution and occurrence of C. thalictroides were associated with the destruction and loss of aquatic habitats. The genetic diversity within and among thirteen populations of C. thalictroides was investigated using ISSR markers. The percentage of polymorphic bands （PPB） was 65.19%. Analysis of Molecular Variance （AMOVA） showed that 33.91% of variability was partitioned among populations. The results indicate C. thalictroides possesses an intermediate level of genetic diversity at species level and lower genetic differentiation between populations. High gene flow via spore dispersal in an earlier period when C. thalictroides was widely distributed in China is a plausible reason for the low genetic differentiation among populations.