Ben-Menni Schuler Samira, Picazo-Aragonés Jesús, Rumsey Fred J, Romero-García Ana Teresa, Suárez-Santiago Víctor N
Department of Botany, Faculty of Sciences, University of Granada, 18071 Granada, Spain.
Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK.
Plants (Basel). 2021 Nov 10;10(11):2425. doi: 10.3390/plants10112425.
Macaronesia has been considered a refuge region of the formerly widespread subtropical lauroid flora that lived in Southern Europe during the Tertiary. The study of relict angiosperms has shown that Macaronesian relict taxa preserve genetic variation and revealed general patterns of colonization and dispersal. However, information on the conservation of genetic diversity and range dynamics rapidly diminishes when referring to pteridophytes, despite their dominance of the herbaceous stratum in the European tropical palaeoflora. Here we aim to elucidate the pattern of genetic diversity and phylogeography of , a hypothesized species of the Tertiary Palaeotropical flora and currently with its populations restricted across Macaronesia and disjunctly in the Sierras de Algeciras (Andalusia, southern Iberian Peninsula). We analysed 12 populations across the species range using eight microsatellite loci, sequences of a region of plastid DNA, and carry out species-distribution modelling analyses. Our dating results confirm the Tertiary origin of this species. The Macaronesian archipelagos served as a refuge during at least the Quaternary glacial cycles, where populations of preserved higher levels of genetic variation than mainland populations. Our data suggest the disappearance of the species in the continent and the subsequent recolonization from Macaronesia. The results of the AMOVA analysis and the indices of clonal diversity and linkage disequilibrium suggest that is a species in which inter-gametophytic outcrossing predominates, and that in the Andalusian populations there was a shift in mating system toward increased inbreeding and/or clonality. The model that best explains the genetic diversity distribution pattern observed in Macaronesia is, the initial and recurrent colonization between islands and archipelagos and the relatively recent diversification of restricted area lineages, probably due to the decrease of favorable habitats and competition with lineages previously established. This study extends to ferns the concept of Macaronesia archipelagos as refugia for genetic variation.
马卡罗尼西亚被认为是第三纪时期生活在南欧的曾经广泛分布的亚热带樟科植物区系的一个避难区域。对残遗被子植物的研究表明，马卡罗尼西亚残遗类群保留了遗传变异，并揭示了殖民化和扩散的一般模式。然而，尽管蕨类植物在欧洲热带古植物区系的草本层中占主导地位，但当涉及到蕨类植物时，关于遗传多样性保护和分布范围动态的信息迅速减少。在这里，我们旨在阐明一种假设的第三纪古热带植物区系物种的遗传多样性模式和系统地理学，该物种目前的种群分布在马卡罗尼西亚各地，并在阿尔赫西拉斯山脉（伊比利亚半岛南部的安达卢西亚）呈间断分布。我们使用八个微卫星位点、叶绿体DNA区域序列分析了该物种分布范围内的12个种群，并进行了物种分布建模分析。我们的年代测定结果证实了该物种起源于第三纪。至少在第四纪冰川周期期间，马卡罗尼西亚群岛充当了一个避难所，该物种的种群在那里保留了比大陆种群更高水平的遗传变异。我们的数据表明该物种在大陆上消失，随后从马卡罗尼西亚重新定殖。AMOVA分析结果以及克隆多样性和连锁不平衡指数表明，该物种以配子体间异交为主，而在安达卢西亚种群中，交配系统向近亲繁殖和/或克隆性增加的方向转变。最能解释在马卡罗尼西亚观察到的遗传多样性分布模式的模型是，岛屿和群岛之间的初始和反复定殖以及受限区域谱系相对较新的多样化，这可能是由于适宜栖息地的减少以及与先前建立的谱系的竞争。这项研究将马卡罗尼西亚群岛作为遗传变异避难所的概念扩展到了蕨类植物。
