Cornetti Luca, Menegon Michele, Giovine Giovanni, Heulin Benoit, Vernesi Cristiano
Department of Biodiversity and Molecular Ecology - Centre for Research and Innovation, Fondazione Edmund Mach, S. Michele all'Adige, Italy ; Department of Life Sciences and Biotechnology, Università di Ferrara, Ferrara, Italy.
Museo di Scienze, Trento, Italy.
PLoS One. 2014 Jan 17;9(1):e85912. doi: 10.1371/journal.pone.0085912. eCollection 2014.
The European common lizard Zootoca vivipara exhibits reproductive bimodality, with populations being either viviparous or oviparous. In the central-eastern Italian Alps oviparous populations (Z. v. carniolica) and viviparous populations (Z. v. vivipara) partly overlap geographically. Studying the evolutionary relationship between these taxa presents an interesting opportunity to gain insight into the evolution of this trait. We aim to: i) test whether Z. v. carniolica, which is endangered, constitutes an ESU (Evolutionary Significant Unity); ii) infer mtDNA divergence time between the Z. v. carniolica clade and all the other Z. vivipara subspecies with the aid of an external calibration point; and iii) describe the phylogeographical and demographic scenarios in the area. To do so we sequenced about 200 individuals for mitochondrial variation; 64 of them were also analysed for three nuclear genes. Furthermore, we analysed the same nuclear markers in 17 individuals from the other oviparous subspecies Z. v. louislantzi and 11 individuals of Z. v. vivipara from widespread geographical origins. The mtDNA and nDNA loci that we examined supported the monophyly of Z. v. carniolica. The mtDNA-based estimate of divergence time between Z. v. carniolica and all the other subspecies indicated a separation at 4.5 Mya (95% CI 6.1-2.6), with about 5% of sequence divergence. Considering that Z. v. carniolica harbours higher genetic diversity, while Z. v. vivipara from central-eastern Alps shows a signature of recent population and spatial expansion, we argue that Z. v. carniolica represents a distinct evolutionary unit, with a presumably long-term evolutionary history of separation. Z. v. carniolica populations, occurring at higher latitudes and altitudes than insofar supposed, live in peat bogs, a seriously threatened habitat: taking into account also its evolutionary distinctness, specific conservation measures should be considered.
欧洲普通蜥蜴（Zootoca vivipara）表现出繁殖方式的双峰性，其种群要么是胎生的，要么是卵生的。在意大利阿尔卑斯山脉中东部，卵生种群（Z. v. carniolica）和胎生种群（Z. v. vivipara）在地理上有部分重叠。研究这些分类单元之间的进化关系为深入了解这一性状的进化提供了一个有趣的机会。我们的目标是：i）测试濒危的Z. v. carniolica是否构成一个进化显著单元（ESU）；ii）借助一个外部校准点推断Z. v. carniolica分支与所有其他Z. vivipara亚种之间的线粒体DNA分歧时间；iii）描述该地区的系统地理学和种群动态情况。为此，我们对约200个个体的线粒体变异进行了测序；其中64个个体还被分析了三个核基因。此外，我们对来自另一个卵生亚种Z. v. louislantzi的17个个体以及来自广泛地理起源的11个Z. v. vivipara个体的相同核标记进行了分析。我们检测的线粒体DNA和核DNA位点支持了Z. v. carniolica的单系性。基于线粒体DNA的Z. v. carniolica与所有其他亚种之间的分歧时间估计表明，它们在450万年前发生了分化（95%置信区间为610 - 260万年前），序列分歧约为5%。鉴于Z. v. carniolica具有更高的遗传多样性，而来自阿尔卑斯山脉中东部的Z. v. vivipara显示出近期种群和空间扩张的特征，我们认为Z. v. carniolica代表一个独特的进化单元，可能具有长期的独立进化历史。Z. v. carniolica种群出现在比之前认为的更高的纬度和海拔地区，生活在泥炭沼泽中，这是一个受到严重威胁的栖息地：考虑到其进化独特性，应考虑采取特定的保护措施。
