Physical and ecological isolation contribute to maintain genetic differentiation between fire salamander subspecies

Landscape features shape patterns of gene flow among populations, ultimately determining where taxa lay along the continuum between panmixia to complete reproductive isolation. Gene flow can be restricted leading to population differentiation in two non-exclusive ways: “physical isolation”, in which geographic distance in combination with the landscape features restricts movement of individuals promoting genetic drift, and “ecological isolation”, in which adaptive mechanisms constrain gene flow between different environments via divergent natural selection. In central Iberia, two fire salamander subspecies occur in parapatry across elevation gradients along the Iberian Central System mountains, while in adjacent Mountains of Toledo Region only one of them occurs. By integrating population and landscape genetic analyses, we show a ubiquitous role of physical isolation between and within mountain ranges, with unsuitable landscapes increasing differentiation between populations. However, a...

景观特征塑造了种群间的基因流（gene flow）模式，最终决定了类群在泛交（panmixia）至完全生殖隔离的连续谱系上所处的位置。基因流可通过两种非互斥的方式受限，进而导致种群分化：一是“物理隔离（physical isolation）”，即地理距离与景观特征共同限制个体移动，推动遗传漂变（genetic drift）的发生；二是“生态隔离（ecological isolation）”，即适应机制通过歧化自然选择（divergent natural selection），约束不同环境间的基因流。在伊比利亚半岛中部，两种火蝾螈（fire salamander）亚种沿伊比利亚中央山脉系（Iberian Central System）的海拔梯度呈邻域分布（parapatry）；而在相邻的托莱多山脉区域（Mountains of Toledo Region），仅分布有其中一种亚种。本研究通过整合种群遗传学与景观遗传学分析，证实了山脉内部及山脉间的物理隔离普遍存在：不适生境会加剧种群间的遗传分化。然而，