García-París M, Alcobendas M, Buckley D, Wake D B
Museo Nacional de Ciencias Naturales, CSIC José Gutiérrez Abascal, 2, 28006 Madrid, Spain.
Evolution. 2003 Jan;57(1):129-43. doi: 10.1111/j.0014-3820.2003.tb00221.x.
We used partial sequences of the cytochrome b mitochondrial DNA (mtDNA) gene, obtained from 76 individuals representing 45 populations of Iberian Salamandra salamandra plus 15 sequences of additional species of Salamandra and related genera, to investigate contact zones. These zones, identified by earlier allozymic and morphological analyses, are between populations of viviparous (S. s. bernardezi and S. s. fastuosa) and ovoviviparous (S. s. gallaica and S. s. terrestris) salamanders. The distribution of mtDNA and nuclear markers is mostly concordant at one contact zone (between S. s. gallaica and S. s. bernardezi), but at another (between S. s. fastuosa and S. s. terrestris) the markers are offset by about 250 km. The observed geographic variation fits a model of mtDNA capture. Among the potential mechanisms responsible for such discordance we favor a combination of range shifts due to climatic fluctuations and biased genetic admixture across moving contact zones. We apply our findings to the issue of possible homoplasy in the evolution of viviparity and conclude that viviparity likely arose only once within S. salamandra.
我们使用了细胞色素b线粒体DNA（mtDNA）基因的部分序列，这些序列来自代表伊比利亚真螈45个种群的76个个体，外加真螈属及相关属其他物种的15个序列，以研究接触带。这些接触带是通过早期的等位酶和形态学分析确定的，位于胎生（S. s. bernardezi和S. s. fastuosa）和卵胎生（S. s. gallaica和S. s. terrestris）真螈种群之间。在一个接触带（S. s. gallaica和S. s. bernardezi之间），mtDNA和核标记的分布大多一致，但在另一个接触带（S. s. fastuosa和S. s. terrestris之间），这些标记偏移了约250公里。观察到的地理变异符合mtDNA捕获模型。在导致这种不一致的潜在机制中，我们倾向于气候波动引起的范围转移与移动接触带中偏向性基因混合的结合。我们将研究结果应用于胎生进化中可能存在的同功性问题，并得出结论，胎生在真螈属中可能仅出现过一次。
