Data from: Local adaptation and the evolution of phenotypic plasticity in Trinidadian guppies (Poecilia reticulata)

Divergent selection pressures across environments can result in phenotypic differentiation that is due to local adaptation, phenotypic plasticity, or both. Trinidadian guppies exhibit local adaptation to the presence or absence of predators, but the degree to which predator-induced plasticity contributes to population differentiation is less clear. We conducted common garden experiments on guppies obtained from two drainages containing populations adapted to high- and low-predation environments. We reared full-sibs from all populations in treatments simulating the presumed ancestral (predator-cues present) and derived (predator-cues absent) conditions and measured water column use, head morphology, and size at maturity. When reared in presence of predator cues, all populations had phenotypes that were typical of a high-predation ecotype. However, when reared in the absence of predator cues, guppies from high- and low-predation regimes differed in head morphology and size at maturity; the qualitative nature of these differences corresponded to those that characterize adaptive phenotypes in high- versus low-predation environments. Thus, divergence in plasticity is due to phenotypic differences between high- and low-predation populations when reared in the absence of predator cues. These results suggest that plasticity might initially play an important role during colonization of novel environments, and then evolve as a by-product of adaptation to the derived environment.

不同环境间的歧化选择压力，可引发种群表型分化，此类分化可由本地适应、表型可塑性，或二者共同作用导致。特立尼达花鳉（Trinidadian guppies）已被证实可针对捕食者的存在与否产生本地适应，但捕食者诱导的可塑性对种群分化的贡献程度仍不甚明确。本研究从两个流域采集花鳉样本，这些流域的种群分别适应高捕食压力与低捕食压力环境，并针对这些种群开展了同质园（common garden）实验。我们将所有种群的全同胞家系饲养于两种处理环境中：分别模拟推测的祖先环境（存在捕食者线索（predator-cues））与衍生环境（缺失捕食者线索），并测定了其水层利用、头部形态与成熟体型三项表型指标。当饲养环境存在捕食者线索时，所有种群均表现出高捕食压力生态型的典型表型特征。但当饲养环境缺失捕食者线索时，高、低捕食压力种群在头部形态与成熟体型上出现差异；此类差异的定性特征，恰好对应高捕食与低捕食环境下适应性表型的差异模式。由此可见，可塑性的歧化源于无捕食者线索环境下高、低捕食压力种群间的表型差异。本研究结果表明，表型可塑性或许在物种定居全新环境的初期发挥了重要作用，随后可作为对衍生环境适应的副产品发生演化。