Data from: Evidence for concerted movement of nuclear and mitochondrial clines in a lizard hybrid zone

Moving hybrid zones provide compelling examples of evolution in action, yet long-term studies that test the assumptions of hybrid zone stability are rare. Using replicated transect samples collected over a 10 year interval from 2002 to 2012, we find evidence for concerted movement of genetic clines in a plateau fence lizard hybrid zone (Sceloporus tristichus) in Arizona. Cline-fitting analyses of SNP and mtDNA data both provide evidence that the hybrid zone shifted northward by approximately two kilometres during the 10 year interval. For each sampling period, the mtDNA cline centre is displaced from the SNP cline centre and maintaining an introgression distance of approximately 3 km. The northward expansion of juniper trees into the Little Colorado River Basin in the early 1900s provides a plausible mechanism for hybrid zone formation and movement, and a broad-scale quantification of recent land cover change provides support for increased woody species encroachment at the southern end of the hybrid zone. However, population processes can also contribute to hybrid zone movement, and the current stability of the ecotone habitats in the centre of the hybrid zone suggests that movement could decelerate in the future.

动态杂交带为正在进行的进化过程提供了极具说服力的实例，但验证杂交带稳定性假设的长期研究却较为罕见。本研究采用2002至2012年十年间采集的重复样带样本，在美国亚利桑那州的高原栅栏蜥蜴（Sceloporus tristichus）杂交带中发现了遗传梯度协同移动的证据。对单核苷酸多态性（Single Nucleotide Polymorphism, SNP）与线粒体DNA（mitochondrial DNA, mtDNA）数据进行梯度拟合分析后，均证实该杂交带在十年间向北移动了约2公里。在每个采样周期中，线粒体DNA梯度中心均偏离单核苷酸多态性梯度中心，并维持约3公里的基因渐渗距离。20世纪初杜松向北扩张进入小科罗拉多河流域，为杂交带的形成与移动提供了合理的机制；而近期大范围的土地覆盖变化量化结果也证实，杂交带南端的木本植物侵占现象有所加剧。不过，种群过程同样可能推动杂交带移动；当前杂交带中部的生态交错带生境仍保持稳定，这表明未来杂交带的移动速度可能会放缓。