Populations of widely distributed species often exhibit geographic variation in functional traits in response to environmental heterogeneity. Such trait variation may be the result of different adaptive mechanisms, including genetically based differentiation, phenotypic plasticity or a combination of both. Disentangling the genetic and environmental components of trait variation may be particularly interesting in crop wild relatives, since they may provide unique reservoirs of genetic diversity for crop improvement. In this study, we assessed ecotypic differentiation and patterns of plasticity to drought in populations of Lupinus angustifolius, a Mediterranean crop wild relative, from two climatically distinct regions in the Iberian Peninsula. Using an outdoor common garden, we compared phenotypic responses of inbred maternal families to two ecologically meaningful water availability treatments (drought and high-moisture). We measured 18 different functional traits related to growth, morphology, phenology and reproduction. Plants in the drought treatment grew less, had lower leaf chlorophyll content and photochemical efficiency, but also reproduced faster, produced larger seeds and altered leaflet morphology through increased leaflet thickness, higher leaflet dry matter content and lower specific leaf area. We also found significant differences between regions that likely reflect adaptation to climatically distinct environments, with populations from the south showing a faster onset of reproduction, higher leaf thickness and higher seed size, consistent with the drier conditions experienced in southern sites. Plasticity to drought was in most cases in the same direction as quantitative genetic differentiation (i.e. cogradient variation), providing evidence of the adaptive value of the plastic change. Our results show that both genetic differentiation and plasticity can generate adaptive phenotypic variation in L. angustifolius, and help to identify potentially valuable genetic resources to incorporate into breeding programmes.

中文翻译：

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作物野生近缘种种群对干旱的可塑性和生态型分化

响应环境的异质性，分布广泛的物种的种群通常在功能性状上表现出地理差异。这种性状变异可能是不同适应机制的结果，包括基于遗传的分化，表型可塑性或两者的结合。解开性状变异的遗传和环境成分在农作物野生近缘种中可能特别令人感兴趣，因为它们可以为作物改良提供独特的遗传多样性贮藏库。在这项研究中，我们评估了羽扇豆种群的生态型分化和可塑性对干旱的模式是来自伊比利亚半岛两个气候不同地区的地中海作物野生近缘种。我们使用一个室外公共花园，将近交产妇家庭的表型反应与两种具有生态意义的可用水处理（干旱和高湿）进行了比较。我们测量了18个与生长，形态，物候和繁殖相关的不同功能性状。经过干旱处理的植物生长较少，叶片叶绿素含量和光化学效率较低，但繁殖速度更快，产生的种子更大，并且通过增加叶片厚度，增加叶片干物质含量和降低比叶面积来改变叶片形态。我们还发现了地区之间的重大差异，这可能反映了对气候不同环境的适应，来自南部的种群显示出较快的繁殖开始，较高的叶片厚度和较高的种子大小，与南部地区经历的干旱条件一致。在大多数情况下，干旱的可塑性与定量遗传分化（即共梯度变化）的方向相同，这为塑性变化的适应性价值提供了证据。我们的结果表明，遗传分化和可塑性均可产生适应性表型变异。L. angustifolius，并帮助确定潜在有价值的遗传资源以纳入育种计划。