Área de Biodiversidad y Conservación, Universidad Rey Juan Carlos. C/ Tulipán s/n, 28933, Móstoles, Spain.
Department of Biology, Oberlin College, Oberlin, OH, 44074, USA.
Am J Bot. 2021 Mar;108(3):443-460. doi: 10.1002/ajb2.1625. Epub 2021 Mar 19.
Gypsum soils in the Mediterranean Basin house large numbers of edaphic specialists that are adapted to stressful environments. The evolutionary history and standing genetic variation of these taxa have been influenced by the geological and paleoclimatic complexity of this area and the long-standing effect of human activities. However, little is known about the origin of Mediterranean gypsophiles and the factors affecting their genetic diversity and population structure.
Using phylogenetic and phylogeographic approaches based on microsatellites and sequence data from nuclear and chloroplast regions, we evaluated the divergence time, genetic diversity, and population structure of 27 different populations of the widespread Iberian gypsophile Lepidium subulatum throughout its entire geographic range.
Lepidium subulatum diverged from its nearest relatives ~3 million years ago, and ITS and psbA/matK trees supported the monophyly of the species. These results suggest that both geological and climatic changes in the region around the Plio-Pleistocene promoted its origin, compared to other evolutionary processes. We found high genetic diversity in both nuclear and chloroplast markers, but a greater population structure in the chloroplast data. These results suggest that while seed dispersal is limited, pollen flow may be favored by the presence of numerous habitat patches that enhance the movement of pollinators.
Despite being an edaphic endemic, L. subulatum possesses high genetic diversity probably related to its relatively old age and high population sizes across its range. Our study highlights the value of using different markers to fully understand the phylogeographic history of plant species.
地中海盆地的石膏土壤中栖息着大量适应恶劣环境的土壤专家。这些分类群的进化历史和现存遗传变异受到该地区地质和古气候复杂性以及人类活动的长期影响。然而，关于地中海石膏植物的起源以及影响其遗传多样性和种群结构的因素知之甚少。
我们使用基于微卫星和核与质体区域序列数据的系统发育和系统地理方法，评估了广泛分布于伊比利亚半岛的 Gypsophila 属 Lepidium subulatum 在其整个地理范围内的 27 个不同种群的分歧时间、遗传多样性和种群结构。
Lepidium subulatum 与其最近的亲缘种在大约 300 万年前分化，ITS 和 psbA/matK 树支持该物种的单系性。这些结果表明，与其他进化过程相比，上新世-更新世时期该地区的地质和气候变化促进了它的起源。我们在核和质体标记中都发现了高遗传多样性，但在质体数据中种群结构更大。这些结果表明，虽然种子传播受到限制，但花粉流可能受到大量生境斑块的促进，这些斑块增强了传粉媒介的移动。
尽管 Lepidium subulatum 是一种土壤特有种，但它具有高度的遗传多样性，这可能与其相对较老的年龄和在其分布范围内的高种群大小有关。我们的研究强调了使用不同标记来充分了解植物物种系统地理历史的价值。
