Data from: Asynchronous diversification of snakes in the North American warm deserts

Aim: We quantify the degree to which co-distributed snakes across the Cochise Filter Barrier (CFB) have a shared history of population divergence and estimate the timing of divergence for each taxon pair. Location: North America. Methods: A single locus dataset was collected (n = 747 individuals) for 12 snake taxon pairs. Phylogeographical structure was estimated for each taxon. Redundancy analyses were used to assess the importance of geographical distance, climate and putative barriers to gene flow in structuring genetic diversity. Hierarchical approximate Bayesian computation was used to estimate the magnitude of synchronicity in divergence times across a well-documented phylogeographical barrier. Lastly, gene divergence and population divergence times were estimated using multiple methods. Results: There is substantial phylogeographical structure in many of the snake taxa, particularly at the CFB. A model containing distance, climate and barriers explained the greatest amount of genetic variation in nearly all taxa. When each variable was examined separately, climate explained the most variation. The hABC model testing indicates that there is overwhelming support for asynchronous phylogeographical histories within these co-distributed taxa. Estimated divergence times range throughout the Quaternary and Neogene. Main Conclusions: We demonstrate that the 12 snake taxon pairs studied here have diversified within the desert Southwest forming distinct Sonoran and Chihuahuan populations, illustrating the importance of this region in driving diversification in North American taxa. Although these groups exhibit the same pattern of lineage formation, there is strong support for asynchronous diversification and little concordance in divergence time estimates.研究目的：我们量化了分布于科奇斯过滤屏障（Cochise Filter Barrier, CFB）的同分布蛇类类群间共享种群分化历史的程度，并估算了每一类群对的分化时间。 研究区域：北美洲。 研究方法：本研究采集了12对蛇类类群的单基因座数据集，共包含747个个体（n=747）。我们首先对每个类群的系统地理结构（phylogeographical structure）进行了估算；随后采用冗余分析（redundancy analyses）评估地理距离、气候及潜在基因流障碍对遗传多样性结构的影响权重；使用分层近似贝叶斯计算（hierarchical approximate Bayesian computation, hABC）估算这一被充分研究的系统地理屏障的分化时间同步性程度；最后通过多种方法估算了基因分化与种群分化时间。 研究结果：多数蛇类类群存在显著的系统地理结构，尤以科奇斯过滤屏障区域最为突出。同时纳入地理距离、气候与障碍因子的模型在几乎所有类群中都解释了最多的遗传变异；当单独检验各变量时，气候对遗传变异的解释度最高。分层近似贝叶斯计算模型检验结果显示，这些同分布类群的系统地理历史存在显著的异步性。估算得到的分化时间跨度覆盖第四纪（Quaternary）与新近纪（Neogene）时期。 主要结论：本研究证实，本次研究的12对蛇类类群在北美西南部沙漠区域发生分化，形成了特征鲜明的索诺兰（Sonoran）与奇瓦瓦（Chihuahuan）种群，阐明了该区域在驱动北美类群分化过程中的关键作用。尽管这些类群呈现出相似的谱系形成模式，但研究结果强烈支持其分化过程具有异步性，且不同类群对的分化时间估算结果一致性极低。