中文摘要：

自2011年7月16日起，通过每周1次的轮虫采集、实验室克隆培养、DNA提取、C01基因扩增、序列测定和分析，研究了九莲塘水体中萼花臂尾轮虫种复合体结构的快速变化，并在28℃和32℃及1．0x10。、3．0x10。和5．0×10%-1cells·mL。斜生栅藻密度下研究了轮虫两姊妹种的适合度特征．结果表明：所得4批35条C01基因部分序列共定义22个单倍型，其中共享单倍型3个．基于C01基因部分序列构建的系统发生树将22个单倍型聚合为2个支系（支系I和支系II）；支系I和支系Ⅱ间的序列差异百分比为14．8％～15．6％，它们应属不同的姊妹种（姊妹种I和姊妹种Ⅱ）．姊妹种Ⅱ的相对丰度较低（仅占1／35），出现时间较短（仅在第2批次出现）；姊妹种1种群内，3个共享单倍型所代表的克隆均存在重叠现象，而其他克隆存在替代现象．三因素方差分析表明，温度对轮虫的净生殖率、种群内禀增长率和后代混交率有显著影响，食物密度对轮虫的平均寿命、净生殖率和种群内禀增长率有显著影响，姊妹种对轮虫的平均寿命、种群内禀增长率和后代混交率有显著影响，温度和姊妹种的交互作用对轮虫的净生殖率和种群内禀增长率有显著影响，温度和食物密度的交互作用对轮虫的后代混交率有极显著影响，食物密度和姊妹种的交互作用对轮虫种群内禀增长率有显著影响．姊妹种I的种群内禀增长率显著高于姊妹种Ⅱ，平均寿命和后代混交率均显著短于或低于姊妹种Ⅱ．

英文摘要：

In order to investigate the rapid variation in the structure of Brachionus calyciflorus com- plex and the fitness traits of the two sibling species, the rotifers were collected once a week from Jiulian Pond during 16 July and 6 August, their CO1 genes were sequenced and analyzed, and their fitness parameters （average lifespan, net reproductive rate, intrinsic rate of population increase and proportion of sexual offspring） were calculated at 28 ℃ and 32 ℃ with 1.0-106, 3.0-106 and 5.0 ×106 cells · mL-1 of Scenedesmus obliquus as food. In total of 35 samples, 22 haplotypes were de- fined, among which two distinct lineages （Lineage I and 11 ） were revealed by phylogenetic analy- sis. Sequence divergence was 14.8%-15.6% between the two lineages, indicating the occurrence of two sibling species （ sibling species I and I[ ）. Sibling species I1 occurred only in the second event of sample collection, and its relative abundance in the density of the species complex was low- er （1/35）. In the population of sibling species I , the clones of three shared haplotypes showed overlap, while the others showed displacement. Three-way ANOVA indicated that temperature af- fected the net reproductive rate, the intrinsic rate of population increase and the proportion of sexual offspring, food level affected the average lifespan, the net reproductive rate and the intrinsic rate of population increase, sibling species affected the average lifespan, the intrinsic rate of population increase and the proportion of sexual offspring. The interaction between temperature and sibling spe- cies affected the net reproductive rate and the intrinsic rate of population increase （P〈0.05）, the interaction between temperature and food level affected the proportion of sexual offspring （P 〈 0. 01 ）, and the interaction between food level and sibling species affected the intrinsic rate of popu- lation increase of the rotifers （P〈0.05）. Sibling species I had a higher intrinsic rate of population increase, a shorter a