Abstract：
Adaptive responses to climate change, based on heritable variation in stress tolerance, may be important for plant population persistence. It is unclear which populations will mount the strongest future adaptive responses. It may be fruitful to identify populations that have escaped trade-offs among performance traits, which can hinder adaptation. Barring strong genetic constraints, the extent of trade-offs may depend on spatial relationships among climate variables shaping different traits. Here, we test for climate-driven ecotypic variation and trade-offs among drought and freezing sensitivity, and growth, for Lemmon\'s willow (Salix lemmonii) in a common garden study of 90 genotypes from 38 sites in the Sierra Nevada, USA. Salix lemmonii exhibits ecotypic variation in leaf turgor loss point, a measure of drought sensitivity, from -0.95 to -0.74 MPa along a gradient of spring snowpack. We also find variation in spring freezing sensitivity with minimum May temperature. However, we find no trade-off, as the climatic gradients shaping these traits are spatially uncorrelated in our study region, despite being negatively correlated across the Sierra Nevada. Species may escape adaptive trade-offs in geographic regions where climate variables are spatially decoupled. These regions may represent valuable reservoirs of heritable adaptive phenotypic variation.
摘要：
对气候变化的适应性反应，基于胁迫耐受性的可遗传变化，可能对植物种群的持久性很重要。目前尚不清楚哪些人群将在未来产生最强的适应性反应。识别出逃避了绩效特征之间权衡取舍的人群可能是富有成果的，这可能会阻碍适应。除非有强烈的遗传限制，权衡的程度可能取决于塑造不同特征的气候变量之间的空间关系。这里,我们测试了气候驱动的生态型变异以及干旱和冰冻敏感性之间的权衡，和增长，对于来自内华达山脉38个地点的90种基因型的普通花园研究中的Lemmon柳树（Salixlemmonii），美国。柳树在叶片膨胀损失点表现出生态型变异，衡量干旱敏感性，从-0.95到-0.74MPa沿弹簧积雪梯度。我们还发现了春季冰冻敏感性随5月最低温度的变化。然而,我们找不到任何权衡,因为在我们的研究区域中，形成这些特征的气候梯度在空间上是不相关的，尽管在整个内华达山脉之间呈负相关。在气候变量在空间上解耦的地理区域，物种可能会逃避适应性权衡。这些区域可能代表有价值的可遗传适应性表型变异库。
