Data from: Geographic variation in phenotypic plasticity in response to dissolved oxygen in an African cichlid fish

Genetic adaptation and phenotypic plasticity are two ways in which organisms can adapt to local environmental conditions. We examined genetic and plastic variation in gill and brain size among swamp (low oxygen; hypoxic) and river (normal oxygen; normoxic) populations of an African cichlid fish, Pseudocrenilabrus multicolor victoriae. Larger gills and smaller brains should be advantageous when oxygen is low, and we hypothesized that the relative contribution of local genetic adaptation versus phenotypic plasticity should be related to potential for dispersal between environments (due to gene flow's constraint on local genetic adaptation). We conducted a laboratory-rearing experiment, with broods from multiple populations raised under high- and low-oxygen conditions. We found that most of the variation in gill size was due to plasticity. However, both plastic and genetic effects on brain mass were detected, as were genetic effects on brain mass plasticity. F1 offspring from populations with the highest potential for dispersal between environments had characteristically smaller and more plastic brains. This phenotypic pattern might be adaptive in the face of gene flow, if smaller brains and increased plasticity confer higher average fitness across environment types.遗传适应（genetic adaptation）与表型可塑性（phenotypic plasticity）是生物体适应局域环境条件的两种核心途径。本研究以非洲慈鲷维多利亚多朴丽鱼（Pseudocrenilabrus multicolor victoriae）的沼泽（低氧，即缺氧hypoxic）种群与河流（正常氧，即常氧normoxic）种群为研究对象，探究其鳃部与脑部大小的遗传变异及可塑性变异。低氧环境下，更大的鳃部与更小的脑部应具备适应性优势。据此我们提出假说：局域遗传适应与表型可塑性的相对贡献，应与种群在不同环境间的扩散潜力相关——这是因为基因流（gene flow）会对局域遗传适应产生约束作用。我们开展了实验室饲养实验，将多个种群的子代幼鱼分别置于高氧与低氧环境中饲养。研究结果显示，鳃部大小的绝大多数变异均由表型可塑性导致。但脑部重量同时受到可塑性与遗传效应的共同影响，脑部重量的可塑性亦存在遗传效应。在不同环境间扩散潜力最高的种群，其F1子代的脑部呈现出体积更小、可塑性更强的典型特征。若更小的脑部与更强的可塑性能够使生物体在各类环境中获得更高的平均适合度（fitness），则该表型特征在基因流存在的情境下具备适应性意义。