Institute for Environmental Sciences, University Koblenz-Landau, Fortstraße 7, 76829, Landau in der Pfalz, Germany.
Biodiversity and Climate Research Centre, Georg-Voigt-Straße 14-16, 60325, Frankfurt/Main, Germany.
J Exp Zool A Ecol Integr Physiol. 2017 Jan;327(1):53-65. doi: 10.1002/jez.2070.
Altering thermal environments impose strong selection pressures on organisms, whose local persistence depends on adaptive phenotypic plastic and genetic responses. Thus far, adaptive change is monitored using phenotypic shifts or molecular markers, although inevitable obstacles are inherent in both methods. In order to circumvent these, it is necessary to find a causal link between adaptive alleles and fitness. Combining both approaches by linking genetic analyses and life-history measurements, a potential genotype-phenotype relationship can be assessed and adaptation at the molecular level demonstrated. For our study, clonal lineages of the freshwater keystone species D. galeata from seven different populations distributed along a latitudinal gradient across Europe were tested for local thermal adaptation in common garden experiments. Fitness-related life-history responses were quantified under different thermal regimes and experimental clones were genotyped at three candidate gene marker loci to investigate a potential genotype-phenotype association. The analyses of the life-history data showed a significant temperature effect on several fitness-related life-history traits recorded in our experiments. However, we could not detect evidence for a direct association at neither candidate gene locus between genotypes and life-history traits. The observed phenotypic shifts might therefore not be based on the tested marker loci EA, M and TF, or in general not coding sequence-based and thus rather reveal phenotypic plasticity in response to thermal variation. Nonetheless, we revealed significant genotype by environment (GxE) interactions at all tested loci, potentially reflecting a contribution of marker loci to certain life-history trait values and contribution of multiple genetic loci to phenotypic traits.
改变热环境对生物施加了强大的选择压力，其局部生存取决于适应性表型可塑性和遗传反应。到目前为止，适应性变化是通过表型变化或分子标记来监测的，尽管这两种方法都存在不可避免的障碍。为了规避这些障碍，有必要找到适应性等位基因与适应性之间的因果关系。通过将遗传分析和生活史测量相结合，结合这两种方法，可以评估潜在的基因型-表型关系，并证明分子水平的适应性。在我们的研究中，对来自欧洲七个不同纬度分布的淡水关键物种 D. galeata 的七个不同种群的克隆谱系进行了常见花园实验，以测试其对当地热适应的能力。在不同的热环境下，对与适应性相关的生活史反应进行了量化，并对三个候选基因标记位点的实验克隆进行了基因型分析，以研究潜在的基因型-表型相关性。对生活史数据的分析表明，温度对我们实验中记录的几个与适应性相关的生活史特征有显著影响。然而，我们在候选基因座 EA、M 和 TF 之间既没有检测到基因型和生活史特征之间的直接关联，也没有检测到直接关联的证据。因此，观察到的表型变化可能不是基于所测试的标记基因座 EA、M 和 TF，或者不是基于一般的编码序列，而是对热变化的表型可塑性。尽管如此，我们在所有测试的基因座上都发现了显著的基因型与环境（GxE）相互作用，这可能反映了标记基因座对某些生活史特征值的贡献以及多个遗传基因座对表型特征的贡献。
