Niche specialization influences adaptive phenotypic plasticity in threespine stickleback

Phenotypic plasticity may be favored in generalist populations if it increases niche width, even in temporally constant environments. Phenotypic plasticity can increase the frequency of extreme phenotypes in a population and thus allow it to make use of a wide resource spectrum. Here we test the prediction that generalist populations should be more plastic than specialists. In a common-garden experiment, we show that solitary, generalist populations of threespine sticklebacks inhabiting small coastal lakes of British Columbia have a higher degree of morphological plasticity than the more specialized sympatric limnetic and benthic species. The ancestral marine stickleback showed low levels of plasticity similar to those of sympatric sticklebacks, implying that the greater plasticity of the generalist population has evolved recently. Measurements of wild populations show that those with mean trait values intermediate between the benthic and limnetic values indeed have higher morphological...表型可塑性（phenotypic plasticity）若能拓宽生态位宽度，即便在环境恒定的情况下，也可能在泛化种群中受到青睐。表型可塑性可提升种群内极端表型的出现频率，从而使其能够利用更为宽泛的资源谱。本研究验证了"泛化种群的可塑性应高于特化种群"这一预测。在同质园实验（common-garden experiment）中，我们发现栖息于不列颠哥伦比亚省小型沿海湖泊的独居性泛化三棘刺鱼（threespine sticklebacks）种群，其形态可塑性程度高于特化程度更高的同域分布浮游型（limnetic）与底栖型（benthic）物种。其祖先类群海洋刺鱼的可塑性水平较低，与同域分布刺鱼的可塑性水平相近，这表明泛化种群的高可塑性是近期演化而来的。对野生种群的测定结果显示，性状均值介于底栖型与浮游型之间的种群，其形态可塑性确实更高……