Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
Instituto del Agua, Universidad de Granada, 18003 Granada, Spain.
J Exp Biol. 2020 Apr 1;223(Pt 7):jeb209676. doi: 10.1242/jeb.209676.
Organisms with wide environmentally induced morphological plasticity and cosmopolitan distribution, e.g. the common freshwater rotifer , are ideal models to study the evolution of plastic polymorphisms and the capacity of zooplankton to adapt to local selection conditions. We investigated population-level differences (population-by-environment interaction) in sensitivity to food availability and temperature-induced phenotypic plasticity between two clones of isolated from neighboring populations in Ruidera Natural Park (Spain) with different trophic statuses: Tinaja lake (mesotrophic) and Cueva Morenilla lake (eutrophic). Using common-garden experiments, each clone proved to have a different sensitivity to food availability, with substantial phenotypic differences between them. When rotifers grew at moderate temperature (15.6°C), low food levels were more efficiently used by the Tinaja versus Cueva Morenilla clone, whereas high food levels were more efficiently used by the Cueva Morenilla versus Tinaja clone. The posterior spine was much longer and the lorica wider in the Tinaja versus Cueva Morenilla clone, with no difference in lorica length. Phylogenetic analysis based on cytochrome oxidase subunit I (COI) gene sequences showed that the two populations have the same haplotype. This is the first study to show possible local adaptation by a rotifer species to habitats that consistently differ in food availability. We also detected an intriguing deviation from the expected negative relationship between posterior spine length and temperature. Our experimental results indicate that intermediate temperatures may activate the gene responsible for spine elongation in This suggests that rotifers in nature could use water temperature as proxy signal of a change in predation risk before defense is needed.
具有广泛环境诱导形态可塑性和世界性分布的生物，例如常见的淡水轮虫，是研究可塑性多态性进化和浮游动物适应当地选择条件能力的理想模型。我们研究了来自西班牙 Ruidera 自然公园（西班牙）两个相邻种群的两个克隆体在对食物可用性和温度诱导表型可塑性的敏感性方面的种群水平差异（种群与环境相互作用）：Tinaja 湖（中营养）和 Cueva Morenilla 湖（富营养）。通过常见的花园实验，每个克隆体都证明对食物可用性具有不同的敏感性，它们之间存在着显著的表型差异。当轮虫在中等温度（15.6°C）下生长时，Tinaja 与 Cueva Morenilla 克隆体相比，低食物水平的利用效率更高，而高食物水平的利用效率则更高Cueva Morenilla 与 Tinaja 克隆体。Tinaja 与 Cueva Morenilla 克隆体的后刺长得更长，壳宽得更宽，壳长没有差异。基于细胞色素氧化酶亚基 I（COI）基因序列的系统发育分析表明，这两个种群具有相同的单倍型。这是第一项表明轮虫物种可能对食物可用性持续存在差异的栖息地进行局部适应的研究。我们还检测到一个有趣的偏离，即后刺长度与温度之间的预期负相关。我们的实验结果表明，中间温度可能会激活负责轮虫后刺伸长的基因。这表明，在需要防御之前，自然中的轮虫可能会将水温用作捕食风险变化的代理信号。
