Ge Y L, Xi Y L, Ma J, Xu D D
Provincial Key Laboratory of Biotic Environment and Ecological Safety in Anhui, College of Life Sciences, Anhui Normal University, Wuhu, Anhui, China.
Genet Mol Res. 2012 Mar 22;11(1):765-74. doi: 10.4238/2012.March.22.7.
Morphological variation in rotifers is affected by environmental conditions, making it hard to identify some rotifer taxa. We examined the rDNA ITS sequences of 10 unspined (KCU1-KCU10) and 17 spined (KCS1-KCS17) Keratell cochlearis clones, 26 two-spined (KQT1-KQT26), 18 single-spined (KQS1-KQS18) and 9 unspined (KQU1-KQU9) K. quadrata clones, and 17 long-spined (BL1-BL17) and 11 short-spined (BS1-BS11) Brachionus forficula clones collected from Lake Tingtang in Wuhu city, China. Molecular phylogenetic trees were constructed by neighbor-joining, maximum-likelihood, maximum parsimony, and Bayesian inference methods using B. calyciflorus as an outgroup. The K. cochlearis clones included 20 haplotypes, the K. quadrata clones included 37 haplotypes, and the B. forficula clones included 25 haplotypes. Different morphotypes of each rotifer species had shared haplotypes. Sequence divergences were 0.1-8.9% among different K. cochlearis haplotypes, and 8.1-8.9% between KCHAP1 (KCU1 and KCU10), KCU3, KCU4 and KCU6, and the other haplotypes. Sequence divergences were 0.1-14.5% among different K. quadrata haplotypes, and 11.9-14.5% between KQS17 and the other haplotypes. Sequence divergences were 0.1-11.7% among different B. forficula haplotypes, 11.0-11.7% between BL15 and the other haplotypes, 9.3-10.1% between BS3 and the other haplotypes, and 11.7% between BL15 and BS3. The four phylogenetic trees all supported that KCHAP1, KCU3, KCU4, KCU6 and the other 16 haplotypes among the 20 K. cochlearis haplotypes, KQS17 and the other 36 haplotypes among the 37 K. quadrata haplotypes, and BL15, BS3 and the other 23 haplotypes among the 25 B. forficula haplotypes all belonged to their own isolated clades. The morphological variation of the three rotifer species was attributed mainly to phenotypic plasticity.
轮虫的形态变异受环境条件影响，这使得一些轮虫分类单元难以鉴定。我们检测了从中国芜湖市汀棠湖采集的10个无棘（KCU1 - KCU10）和17个有棘（KCS1 - KCS17）的耳蜗环轮虫克隆、26个双棘（KQT1 - KQT26）、18个单棘（KQS1 - KQS18）和9个无棘（KQU1 - KQU9）的方形环轮虫克隆，以及17个长棘（BL1 - BL17）和11个短棘（BS1 - BS11）的剪形臂尾轮虫克隆的rDNA ITS序列。以萼花臂尾轮虫作为外类群，采用邻接法、最大似然法、最大简约法和贝叶斯推断法构建分子系统发育树。耳蜗环轮虫克隆包含20个单倍型，方形环轮虫克隆包含37个单倍型，剪形臂尾轮虫克隆包含25个单倍型。每个轮虫物种的不同形态型具有共享单倍型。不同耳蜗环轮虫单倍型之间的序列差异为0.1 - 8.9%，KCHAP1（KCU1和KCU10）、KCU3、KCU4和KCU6与其他单倍型之间的序列差异为8.1 - 8.9%。不同方形环轮虫单倍型之间的序列差异为0.1 - 14.5%，KQS17与其他单倍型之间的序列差异为11.9 - 14.5%。不同剪形臂尾轮虫单倍型之间的序列差异为0.1 - 11.7%，BL15与其他单倍型之间的序列差异为11.0 - 11.7%，BS3与其他单倍型之间的序列差异为9.3 - 10.1%，BL15与BS3之间的序列差异为11.7%。这四棵系统发育树均支持耳蜗环轮虫20个单倍型中的KCHAP1、KCU3、KCU4、KCU6和其他16个单倍型，方形环轮虫37个单倍型中的KQS17和其他36个单倍型，以及剪形臂尾轮虫25个单倍型中的BL15、BS3和其他23个单倍型均属于各自独立的分支。这三种轮虫物种的形态变异主要归因于表型可塑性。
