Strumia Sandro, Santangelo Annalisa, Galise Teresa Rosa, Cozzolino Salvatore, Cafasso Donata
Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania "Luigi Vanvitelli", Caserta, Italy.
Department of Biology, University of Naples Federico II, Naples, Italy.
Front Plant Sci. 2021 Nov 10;12:737111. doi: 10.3389/fpls.2021.737111. eCollection 2021.
Several past and recent climatic and geological events have greatly influenced the current distribution of coastal species around the Mediterranean Basin. As a consequence, the reconstruction of the distributional history of these species is challenging. In this study, we used both chloroplast and nuclear SNPs to assess the levels of genetic differentiation, contemporary/historical levels of gene flow, and demographic history for the three only known (one mainland and two insular) populations of , a rare Mediterranean coastal rocky halophyte. Plastid genome analysis revealed very low intraspecific haplotype variation and partial admixture among Capri and Palinuro populations with at least two independent colonization events for the Strombolicchio islet. Nuclear SNPs variation consistently identified three distinct genetic clusters corresponding to our sampling localities. Furthermore, strong genetic isolation was confirmed by both historical and contemporary levels of migration among the three populations. The DIYABC analysis identified two introductions temporally separated from Palinuro to Capri (ca.25 Mya) and subsequently to Strombolicchio (ca.09 Mya) as the most likely hypothesis for the current distribution of . Regardless of their small population sizes, all study sites supported high-genetic diversity maintained by outcrossing and random mating between individuals owing largely to wind pollination, an exclusive trait among Mediterranean narrow endemics. In conclusion, the patterns observed confirm that some Mediterranean endemics are not necessarily "evolutionary dead-ends" but rather represent species that have extensive demographic stability and a strong evolutionary legacy.
过去和近期的一些气候和地质事件极大地影响了地中海盆地周边沿海物种的当前分布。因此，重建这些物种的分布历史具有挑战性。在本研究中，我们使用叶绿体和核单核苷酸多态性（SNP）来评估一种稀有的地中海沿海岩石盐生植物的三个已知种群（一个大陆种群和两个岛屿种群）的遗传分化水平、当代/历史基因流水平以及种群历史。质体基因组分析显示种内单倍型变异极低，卡普里岛和帕利努罗种群之间存在部分混合，斯特龙博利基奥小岛至少有两次独立的定殖事件。核SNP变异一致地识别出对应于我们采样地点的三个不同遗传簇。此外，三个种群之间的历史和当代迁移水平均证实了强烈的遗传隔离。DIYABC分析确定了从帕利努罗到卡普里岛（约2500万年前）以及随后到斯特龙博利基奥岛（约900万年前）的两次时间上相隔的引入是该物种当前分布的最可能假设。尽管种群规模较小，但所有研究地点都支持由异交和个体间随机交配维持的高遗传多样性，这主要归因于风媒授粉，这是地中海狭域特有植物的一个独特特征。总之，观察到的模式证实，一些地中海特有植物不一定是“进化死胡同”，而是代表具有广泛种群稳定性和强大进化遗产的物种。
