Temperate zone isolation by climate: an extension of Janzen’s 1967 hypothesis

One of the most stunning patterns of the distribution of life on Earth is the latitudinal biodiversity gradient. In an influential paper, Janzen (1967) predicted that tropical mountains are more effective migration barriers than temperate mountains of the same elevation because annual temperature variation in the tropics is lower. A great deal of research has demonstrated that the mechanism envisioned by Janzen operates at broad latitudinal scales. However, the extent that the mechanism mediates biodiversity generally, and at smaller scales, is far less understood. We investigated if climate overlap is associated with genetic similarity between populations within temperate regions using lizards in the Sierra Nevada mountain range, California, as a study system. By comparing genetic differentiation between high- and low-elevation populations, we found that in addition to the expected strong pattern of isolation by distance (IBD), climate overlap values were negatively associated with gen..., This dataset was collected by double-digest restriction-site associated DNA sequencing (ddRAD-seq) of western fence lizards (Sceloporus occidentalis) in California, USA., No proprietary software is needed to open the data files included.地球上生命分布最引人注目的模式之一便是纬度生物多样性梯度（latitudinal biodiversity gradient）。在一篇极具影响力的论文中，简森（Janzen, 1967）提出预测：相较于相同海拔的温带山地，热带山地是更为高效的迁移障碍，这是因为热带地区的年温度波动幅度更低。大量研究已证实，简森所设想的这一机制在大尺度纬度范围内发挥作用。然而，该机制在整体生物多样性调控以及小尺度上的作用程度，目前仍鲜为人知。本研究以美国加利福尼亚州内华达山脉（Sierra Nevada mountain range）的蜥蜴为研究对象，探讨温带区域内种群间的气候重叠度是否与遗传相似性相关。通过比较高海拔与低海拔种群间的遗传分化，我们发现：除了预期存在的显著距离隔离（isolation by distance, IBD）模式外，气候重叠度与遗传[原文此处截断]呈负相关关系。本数据集通过对美国加利福尼亚州的西方强棱蜥（western fence lizard, Sceloporus occidentalis）进行双酶切限制性位点关联DNA测序（double-digest restriction-site associated DNA sequencing, ddRAD-seq）获得。无需使用专有软件即可打开所包含的数据文件。