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）是生物体适配局部环境条件的两种核心策略。本研究以非洲慈鲷维多利亚朴丽鱼（Pseudocrenilabrus multicolor victoriae）为研究对象，针对其沼泽（低氧，即缺氧（hypoxic））与河流（正常氧，即常氧（normoxic））种群，分析了鳃与脑容量的遗传变异及可塑性差异。低氧环境中，更大的鳃尺寸与更小的脑容量应具备适应性优势；据此我们提出假说：局部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——基因流（gene flow）会对局部遗传适应形成制约。我们开展了实验室饲养实验，将多个种群的繁育家系分别置于高氧与低氧环境下培育。结果显示，鳃尺寸的绝大多数变异源自表型可塑性。但脑重量同时受到可塑性与遗传效应的调控，脑重量的可塑性亦存在遗传差异。来自环境间扩散潜力最高的种群的子一代（F1）个体，其脑容量更小且可塑性更强。若更小的脑容量与增强的可塑性能够提升跨环境类型的平均适合度（fitness），那么这种表型模式或许可在基因流的影响下维持适应性。