镜湖萼花臂尾轮虫种群内不同基因型克隆的生活史特征

应用生命表统计学等方法，比较了15、20、25和30℃4个温度下镜湖萼花臂尾轮虫种群内13个不同基因型克隆的生命表统计学参数和后代混交雌体百分率等生活史特征．结果表明：轮虫的世代时间、平均寿命、出生时的生命期望值、内禀增长率、净生殖率和后代混交雌体百分率对升高温度的反应均因克隆的不同而存在差异；温度、克隆及两者间的交互作用对其也都具有极显著影响．表明水环境在温度等方面所具有的时间异质性可能是镜湖萼花臂尾轮虫种群丰富的遗传变异得以维持的原因之一；自然选择出现在共存的克隆中，但其强度较低或作用时间较短是克隆共存的重要原因；遗传漂变可能在种群的基因型频率变化中起重要作用．不同基因型轮虫克隆的存在对其种群在水环境中的持续存在具有重要意义．

Life history characteristics of different genotype clones of Brachionus calyciflorus (Rotifera) population in Jinghu Lake

By means of life table demographic approach, the life-table demographic parameters and the percentage of mictic females in the offspring of thirteen genetically different Brachionus calyciflorus clones were studied at 15 degrees C, 20 degrees C, 25 degrees C and 30 degrees C. The results showed that the responses of the generation time, average lifespan, life expectancy at hatching, intrinsic rate of population increase, net reproductive rate, and percentage of mictic females in the offspring of B. calyciflorus to increasing temperature differed with rotifer clones. Temperature, clone, and their interaction influenced the life-table demographic parameters and the percentage of mictic females in the offspring of B. calyciflorus significantly. The temporal heterogeneity of water temperature could be one of the reasons for the high genetic diversity in B. calyciflorus population in Jinghu Lake. Natural selection occurred in coexisting clones, and its function might be too weak or too time-limited to make the clonal exclusion occur. Genetic drift might play an important role in genotype frequency variation. The coexistence of different genotype clones of B. calyciflorus population is of significance for the existence of the population in water environment.