Ecology and Evolution in Microbial Model Systems, EEMiS, Department of Biology and Environmental Science, Linnaeus University, SE-391 82, Kalmar, Sweden.
Swedish University of Agricultural Sciences, Department of Aquatic Resources, SE-702 15, Örebro, Sweden.
Sci Rep. 2018 Jan 8;8(1):22. doi: 10.1038/s41598-017-18413-8.
Environmental heterogeneity is a key determinant of genetic and phenotypic diversity. Stable and homogenous environments tends to result in evolution of specialism and local adaptations, while temporally unpredictable environments may maintain a diversity of specialists, promote generalist strategies, or favour diversified bet hedging strategies. We compared salinity tolerance between two anadromous subpopulations of pike (Esox Lucius) that utilize freshwater spawning sites with different salinity regimes. Eggs from each population were artificially fertilized and incubated in a salinity gradient (0, 3, 5, 7, and 9 psu) using a split-brood design. Effects on embryonic development, hatching success, survival of larvae, and fry body length were compared between populations and families. The population naturally spawning in the stable freshwater habitat showed signs of specialization for freshwater spawning. The population exposed to fluctuating selective pressure in a spawning area with occasional brackish water intrusions tolerated higher salinities and displayed considerable variation in reaction norms. Genetic differences and plasticity of salinity tolerance may enable populations to cope with changes in salinity regimes associated with future climate change. That geographically adjacent subpopulations can constitute separate units with different genetic characteristics must be considered in management and conservation efforts to avoid potentially negative effects of genetic admixture on population fitness and persistence.
环境异质性是遗传和表型多样性的关键决定因素。稳定和同质的环境往往导致特化和局部适应的进化，而时间不可预测的环境可能会维持多种专家，促进通才策略，或有利于多样化的套期保值策略。我们比较了利用不同盐度制度的淡水产卵地的两种洄游性梭子鱼（Esox Lucius）亚种群的盐度耐受性。每个种群的卵都采用分卵设计，在 0、3、5、7 和 9 psu 的盐度梯度中进行人工受精和孵化。比较了种群和家族之间对胚胎发育、孵化成功率、幼虫存活率和鱼苗体长的影响。在稳定的淡水栖息地自然产卵的种群表现出对淡水产卵的特化迹象。在产卵区受到间歇性咸水入侵的选择压力波动的种群，能耐受更高的盐度，并表现出反应规范的显著变化。盐度耐受性的遗传差异和可塑性可能使种群能够应对与未来气候变化相关的盐度变化。在管理和保护工作中，必须考虑到地理上相邻的亚种群可以构成具有不同遗传特征的独立单位，以避免遗传混合对种群适应性和持久性产生潜在的负面影响。
