Influence of a climatic gradient on genetic exchange between two oak species

Premise of the study. In plant groups with limited intrinsic barriers to gene flow, it is thought that environmental conditions can modulate interspecific genetic exchange. Oaks are known for limited barriers to gene flow among closely related species. Here, we use Quercus as a living laboratory in which to pursue a fundamental question in plant evolution: do environmental gradients restrict or promote genetic exchange between species? Methods. We focused on two North American oaks, the rare Q. dumosa and the widespread Q. berberidifolia. We sampled intensively along a contact zone in California. We sequenced restriction site associated DNA markers and measured vegetative phenotype. We tested for genetic exchange, the association with climate, and the effect on phenotype. Key results. There is evidence for genetic exchange between the species. Admixed plants are found in areas of intermediate climate, while less admixed plants are found at the extremes of the climatic gradient. Genetic ...研究前提：在基因流内在屏障有限的植物类群中，学界普遍认为环境条件可调控种间遗传交换。栎属（Quercus）植物以其近缘物种间基因流屏障有限为典型特征。本研究以栎属作为活体实验体系，旨在解答植物演化领域的核心问题：环境梯度是否会限制或促进物种间的遗传交换？ 研究方法：本研究聚焦于两种北美栎属植物：珍稀的Q. dumosa（*Quercus dumosa*）与广布的Q. berberidifolia（*Quercus berberidifolia*）。我们在加利福尼亚州的物种接触带开展了高密度采样，对限制性酶切位点关联DNA（restriction site associated DNA, RAD）标记进行测序，并测定其营养体表型。本研究分别检验了物种间的遗传交换现象、其与气候的关联以及对表型的影响。 主要研究结果：本研究发现两物种间存在遗传交换的证据。遗传混合个体分布于气候中等的区域，而遗传混合程度较低的个体则分布于气候梯度的两端。遗传……