Understanding which hydraulic traits are under genetic control and/or are phenotypically plastic is essential in understanding how tree species will respond to rapid shifts in climate. We quantified hydraulic traits in Eucalyptus obliqua L'Her. across a precipitation gradient in the field to describe (i) trait variation in relation to long-term climate and (ii) the short-term (seasonal) ability of traits to adjust (i.e., phenotypic plasticity). Seedlings from each field population were raised under controlled conditions to assess (iii) which traits are under strong genetic control. In the field, drier populations had smaller leaves with anatomically thicker xylem vessel walls, a lower leaf hydraulic vulnerability and a lower water potential at turgor loss point, which likely confers higher hydraulic safety. Traits such as the water potential at turgor loss point and ratio of sapwood to leaf area (Huber value) showed significant adjustment from wet to dry conditions in the field, indicating phenotypic plasticity and importantly, the ability to increase hydraulic safety in the short term. In the nursery, seedlings from drier populations had smaller leaves and a lower leaf hydraulic vulnerability, suggesting that key traits associated with hydraulic safety are under strong genetic control. Overall, our study suggests a strong genetic control over traits associated with hydraulic safety, which may compromise the survival of wet-origin populations in drier future climates. However, phenotypic plasticity in physiological and morphological traits may confer sufficient hydraulic safety to facilitate genetic adaptation.

中文翻译：

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表型可塑性和功能性状的遗传适应影响液压效率和安全性的种内变异

了解哪些水力性状处于遗传控制之下和/或在表型上是可塑性的，这对于理解树种将如何对气候的快速变化做出响应至关重要。我们量化了桉树的水力性状L'Her。跨越田间的降水梯度来描述（i）与长期气候相关的性状变化和（ii）性状的短期（季节性）适应能力（即表型可塑性）。在受控条件下饲养每个田间种群的幼苗，以评估（iii）哪些性状处于强大的遗传控制之下。在田间，较干燥的种群的叶片较小，在解剖学上木质部血管壁较厚，叶片的水力脆弱性较低，并且在膨松损失点的水势较低，这可能带来更高的水力安全性。在田间从湿到干条件，在膨松损失点的水势和边材与叶面积的比（Huber值）等特性显示出显着的调节，表明其表型可塑性，重要的是，在短期内提高液压安全性的能力。在苗圃中，干燥种群的幼苗叶片较小，叶片水力脆弱性较低，这表明与水力安全性相关的关键性状处于强大的遗传控制之下。总体而言，我们的研究表明，对与水力安全性相关的性状进行了强有力的遗传控制，这可能会损害湿原种群在较干燥的未来气候中的生存。但是，生理和形态性状的表型可塑性可能赋予足够的水力安全性以促进遗传适应。我们的研究表明，对与水力安全相关的性状进行强有力的遗传控制，这可能会损害在较干燥的未来气候中湿地居民的生存。但是，生理和形态性状的表型可塑性可能赋予足够的水力安全性以促进遗传适应。我们的研究表明，对与水力安全相关的性状进行强有力的遗传控制，这可能会损害在较干燥的未来气候中湿地居民的生存。但是，生理和形态性状的表型可塑性可能赋予足够的水力安全性以促进遗传适应。