Stojilkovič Valentina, Záveská Eliška, Frajman Božo
Department of Botany, University of Innsbruck, Innsbruck, Austria.
Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.
Front Plant Sci. 2022 Jun 23;13:815379. doi: 10.3389/fpls.2022.815379. eCollection 2022.
The Mediterranean Basin is an important biodiversity hotspot and one of the richest areas in the world in terms of plant diversity. Its flora parallels in several aspects that of the Eurasian steppes and the adjacent Irano-Turanian floristic region. The alliance spans this immense area from the western Mediterranean to Central Asia. Using an array of complementary methods, ranging from phylogenomic and phylogenetic data through relative genome size (RGS) estimation to morphometry, we explored relationships and biogeographic connections among taxa of this group. We identified the main evolutionary lineages, which mostly correspond to described taxa. However, despite the use of highly resolving Restriction Site Associated DNA (RAD) sequencing data, relationships among the main lineages remain ambiguous. This is likely due to hybridisation, lineage sorting triggered by rapid range expansion, and polyploidisation. The phylogenomic data identified cryptic diversity in the Mediterranean, which is also correlated with RGS and, partly, also, morphological divergence, rendering the description of a new species necessary. Biogeographic analyses suggest that Western Asia is the source area for the colonisation of the Mediterranean by this plant group and highlight the important contribution of the Irano-Turanian region to the high diversity in the Mediterranean Basin. The diversification of the alliance in the Mediterranean was triggered by vicariance in isolated Pleistocene refugia, morphological adaptation to divergent ecological conditions, and, to a lesser extent, by polyploidisation.
地中海盆地是一个重要的生物多样性热点地区，也是世界上植物多样性最丰富的地区之一。其植物区系在几个方面与欧亚草原和相邻的伊朗 - 图兰植物区系相似。该植物类群分布于从地中海西部到中亚的广阔区域。我们运用了一系列互补方法，从系统基因组学和系统发育数据到相对基因组大小（RGS）估计，再到形态测量学，来探究该类群各分类单元之间的关系和生物地理联系。我们确定了主要的进化谱系，它们大多与已描述的分类单元相对应。然而，尽管使用了高分辨率的限制性位点相关DNA（RAD）测序数据，主要谱系之间的关系仍然不明确。这可能是由于杂交、快速范围扩张引发的谱系分选以及多倍体化造成的。系统基因组学数据揭示了地中海地区存在隐秘的多样性，这也与RGS相关，并且在一定程度上与形态差异相关，因此有必要描述一个新物种。生物地理分析表明，西亚是该植物类群在地中海殖民的源区，并突出了伊朗 - 图兰地区对地中海盆地高度多样性的重要贡献。该植物类群在地中海的多样化是由更新世孤立避难所中的地理隔离、对不同生态条件的形态适应以及在较小程度上由多倍体化引发的。
