镜湖萼花臂尾轮虫夏季种群等位酶分析以及克隆间的生殖差异

Allozyme analysis on the summer population of Brachionus calyciflorus (Rotifera) in Lake Jinghu and reproductive variation among clones

应用聚丙烯酰胺凝胶垂直板电泳技术和特异性染色方法,对采自芜湖市镜湖的萼花臂尾轮虫(Brachionuscalyciflorus)夏季种群内的16个克隆进行了等位酶分析。在检测的6种等位酶系统中,依据葡萄糖磷酸异构酶(GPI)和苹果酸脱氢酶(MDH)的酶谱在克隆间所存在的明显差异,将镜湖萼花臂尾轮虫夏季种群内的16个克隆划分为4个互不相同的克隆群。对由4个克隆群中分别随机选取的1个克隆(共4个克隆,分别命名为克隆A、克隆B、克隆C和克隆D)在4种斜生栅藻(Scenedesmusobliquus)密度(1.0,2.0,4.0和8.0×106cells/ml)下的孤雌生殖和有性生殖所作的研究发现,食物密度、克隆以及两者间的交互作用对轮虫的种群瞬时增长率、种群中的混交雌体百分率、混交雌体受精率和休眠卵产量等4项指标均有显著影响。4克隆中,克隆D的这4项指标均最高,而克隆B的种群瞬时增长率以及克隆A的其他3项指标均最低。克隆B的种群瞬时增长率、种群中的混交雌体百分率和混交雌体受精率均与食物密度间无显著的相关性;克隆A和C的种群瞬时增长率与食物密度间呈曲线相关,而其种群中的混交雌体百分率和混交雌体受精率均与食物密度间无显著的相关性;克隆D的种群瞬时增长率、种群中的混交雌体百分率和混交雌体受精率均与食物密度间呈曲线相关。这些结果表明:镜湖萼花臂尾轮虫夏季种群内存在“克隆共存”现象。

Patterns of genetic variation among Brachionus calyciflorus clones collected during summer from Lake Jinghu, Wuhu （China） were determined using vertical polyacrylamide gel electrophoresis of isoenzymes. Two of the six enzymes assayed-malic dehydrogenase （MDH） and glucose phosphate isomerase （GPI） —were variable, and were selected to screen the 16 clones obtained from field collections. Four composite electromorphs formed by combining isozymes variants were found in the 16 clones. The asexual and sexual reproductions of the four clones （clone A, B, C and D）, each of which was randomly selected from the four composite electromorphs respectively, were compared under four concentrations （ 1.0, 2.0, 4.0, 8.0×10^6 cells/ml） of alga Scenedesmus obliquus. The results showed that there were significant effects of food concentration, clone and their interaction on the instantaneous rate of population increase, mixis rate, fertilization rate and resting egg production of B. calyciflorus. Among the four clones, instantaneous rate of population growth, mixis rate, fertilization rate and resting egg production of Clone D were all the largest, but the growth rate of Clone B as well as the mixis rate, fertilization rate and resting egg production of Clone A were the smallest. There were no significant correlations between food concentration and the rate of population increase of Clone B as well as the mixis rate and fertilization rate of Clone A, B and C. However, the relationships between food concentration and the rate of population increase of Clone A and C were significantly curvilinear, with the regression equation Y=0.019X^2-0.209X＋0.638 and Y=0.042X^2-0.402X＋0.852, respectively. The relationships between the food concentration and the instant rate of population increase, the mixis rate and the fertilization rate of clone D were all significantly curvilinear, with the following regression equations Y=-0.052X^2＋0.609X-0.667, Y=0.994X^2-15.763X＋73.424 and Y=-0.251X^2＋15.940X-15.446, respectively. We conclude that the phenomenon of “clonal coexistence” exits in the summer population of B. calyciflorus from Jinghu Lake, and some clones display significant variation genetically and ecologically [ Acta Zoologica Sinica 51（4） ： 678-684, 2005].