Gutiérrez-Rodríguez Jorge, Barbosa A Márcia, Martínez-Solano Íñigo
Museo Nacional de Ciencias Naturales, CSIC, c/ José Gutiérrez Abascal, 2, 28006 Madrid, Spain.
Centro de Investigação em Biodiversidade e Recursos Genéticos (CIBIO/InBIO) - Universidade de Évora, 7004-516 Évora, Portugal.
Mol Phylogenet Evol. 2017 Jul;112:122-137. doi: 10.1016/j.ympev.2017.04.022. Epub 2017 Apr 25.
Inference of population histories from the molecular signatures of past demographic processes is challenging, but recent methodological advances in species distribution models and their integration in time-calibrated phylogeographic studies allow detailed reconstruction of complex biogeographic scenarios. We apply an integrative approach to infer the evolutionary history of the Iberian ribbed newt (Pleurodeles waltl), an Ibero-Maghrebian endemic with populations north and south of the Strait of Gibraltar. We analyzed an extensive multilocus dataset (mitochondrial and nuclear DNA sequences and ten polymorphic microsatellite loci) and found a deep east-west phylogeographic break in Iberian populations dating back to the Plio-Pleistocene. This break is inferred to result from vicariance associated with the formation of the Guadalquivir river basin. In contrast with previous studies, North African populations showed exclusive mtDNA haplotypes, and formed a monophyletic clade within the Eastern Iberian lineage in the mtDNA genealogy. On the other hand, microsatellites failed to recover Moroccan populations as a differentiated genetic cluster. This is interpreted to result from post-divergence gene flow based on the results of IMA2 and Migrate analyses. Thus, Moroccan populations would have originated after overseas dispersal from the Iberian Peninsula in the Pleistocene, with subsequent gene flow in more recent times, implying at least two trans-marine dispersal events. We modeled the distribution of the species and of each lineage, and projected these models back in time to infer climatically favourable areas during the mid-Holocene, the last glacial maximum (LGM) and the last interglacial (LIG), to reconstruct more recent population dynamics. We found minor differences in climatic favourability across lineages, suggesting intraspecific niche conservatism. Genetic diversity was significantly correlated with the intersection of environmental favourability in the LIG and LGM, indicating that populations of P. waltl are genetically more diverse in regions that have remained environmentally favourable through the last glacial cycle, particularly southern Iberia and northern Morocco. This study provides novel insights into the relative roles of geology and climate on the biogeography of a biodiversity hotspot.
从过去人口动态过程的分子特征推断种群历史具有挑战性，但物种分布模型的最新方法进展及其在时间校准系统地理学研究中的整合，使得详细重建复杂的生物地理情景成为可能。我们采用综合方法来推断伊比利亚肋突螈（Pleurodeles waltl）的进化历史，这是一种伊比利亚 - 马格里布地区的特有物种，其种群分布在直布罗陀海峡南北两侧。我们分析了一个广泛的多基因座数据集（线粒体和核DNA序列以及十个多态微卫星位点），发现伊比利亚种群中存在一个可追溯到上新世 - 更新世的东西向深层系统地理间断。这种间断被推断是由与瓜达尔基维尔河流域形成相关的地理隔离造成的。与之前的研究不同，北非种群显示出独特的线粒体DNA单倍型，并在mtDNA系统发育树中伊比利亚东部谱系内形成一个单系分支。另一方面，微卫星未能将摩洛哥种群识别为一个分化的遗传簇。根据IMA2和Migrate分析结果，这被解释为是分歧后基因流的结果。因此，摩洛哥种群可能起源于更新世从伊比利亚半岛的海外扩散之后，随后在更近的时期有基因流，这意味着至少有两次跨海洋扩散事件。我们对该物种及其每个谱系的分布进行了建模，并将这些模型回溯到过去，以推断全新世中期、末次盛冰期（LGM）和末次间冰期（LIG）期间气候适宜的区域，从而重建更近时期的种群动态。我们发现不同谱系在气候适宜性方面存在微小差异，这表明种内生态位保守性。遗传多样性与LIG和LGM期间环境适宜性的交集显著相关，这表明在过去冰川周期中环境一直适宜的地区，特别是伊比利亚南部和摩洛哥北部，伊比利亚肋突螈的种群在遗传上更加多样化。这项研究为地质和气候在生物多样性热点地区生物地理学中的相对作用提供了新的见解。
