Eawag, Swiss Federal Institute of Aquatic Science and Technology , Department of Aquatic Ecology, 133 Überlandstrasse, 8600 Dübendorf, Switzerland.
Institute of Biological Research , Branch of the National Institute of Research and Development for Biological Sciences, 48 Republicii, 400015 Cluj-Napoca, Romania.
Environ Sci Technol. 2016 Apr 5;50(7):3416-24. doi: 10.1021/acs.est.5b05973. Epub 2016 Mar 10.
Zooplankton communities can be strongly affected by cyanobacterial blooms, especially species of genus Daphnia, which are key-species in lake ecosystems. Here, we explored the effect of microcystin/nonmicrocystin (MC/non-MC) producing cyanobacteria in the diet of experimental Daphnia galeata populations composed of eight genotypes. We used D. galeata clones hatched from ephippia 10 to 60 years old, which were first tested in monocultures, and then exposed for 10 weeks as mixed populations to three food treatments consisting of green algae combined with cyanobacteria able/unable of producing MC. We measured the expression of nine genes potentially involved in Daphnia acclimation to cyanobacteria: six protease genes, one ubiquitin-conjugating enzyme gene, and two rRNA genes, and then we tracked the dynamics of the genotypes in mixed populations. The expression pattern of one protease and the ubiquitin-conjugating enzyme genes was positively correlated with the increased fitness of competing clones in the presence of cyanobacteria, suggesting physiological plasticity. The genotype dynamics in mixed populations was only partially related to the growth rates of clones in monocultures and varied strongly with the food. Our results revealed strong intraspecific differences in the tolerance of D. galeata clones to MC/non-MC-producing cyanobacteria in their diet, suggesting microevolutionary effects.
浮游动物群落可能会受到蓝藻水华的强烈影响，特别是水蚤属的物种，它们是湖泊生态系统中的关键物种。在这里，我们研究了含有微囊藻毒素/非微囊藻毒素（MC/non-MC）的蓝藻在由 8 种基因型组成的实验性大型溞种群饮食中的作用。我们使用了从 10 到 60 年的休眠卵孵化的大型溞克隆体，这些克隆体首先在纯培养物中进行了测试，然后作为混合种群暴露于 10 周，接受三种食物处理，包括与能够/不能够产生 MC 的蓝藻混合的绿藻。我们测量了九个可能参与大型溞对蓝藻适应的基因的表达：六个蛋白酶基因、一个泛素连接酶基因和两个 rRNA 基因，然后跟踪了混合种群中基因型的动态。一种蛋白酶和泛素连接酶基因的表达模式与竞争克隆在蓝藻存在下适应性的提高呈正相关，表明存在生理可塑性。混合种群中的基因型动态与克隆在纯培养物中的生长速率只有部分相关，并且强烈依赖于食物。我们的研究结果揭示了大型溞克隆体对其饮食中含有 MC/non-MC 的蓝藻的耐受性存在强烈的种内差异，这表明存在微观进化效应。
