Data from: Pliocene-Pleistocene ecological niche evolution shapes the phylogeography of a Mediterranean plant group

Estimating species ability to adapt to environmental changes is crucial to understand their past and future response to climate change. The Mediterranean basin has experienced remarkable climatic changes since the Miocene, which have greatly influenced the evolution of the Mediterranean flora. Here we examine the evolutionary history and biogeographic patterns of two sedge sister species (Carex, Cyperaceae) restricted to the western Mediterranean basin, but with Pliocene fossil record in central Europe. In particular, we estimated the evolution of climatic niches through time and its influence in lineage differentiation. We carried out a dated phylogenetic-phylogeographic study based on seven DNA regions (nDNA and ptDNA) and fingerprinting data (AFLPs), and modelled ecological niches and species distributions for the Pliocene, Pleistocene, and present. Phylogenetic and divergence time analyses revealed that both species form a monophyletic lineage originated in the late Pliocene-early Pleistocene. We detected clear genetic differentiation between both species with distinct genetic clusters in disjunct areas, indicating the predominant role of geographic barriers limiting gene flow. We found a remarkable shift in the climatic requirements between Pliocene and extant populations, although the niche seems to have been relatively conserved since the Pleistocene split of both species. This study highlights how an integrative approach combining different data sources and analyses, including fossils, allows solid and robust inferences about the evolutionary history of a plant group since the Pliocene.

评估物种适应环境变化的能力，是理解其过去与未来对气候变化响应的核心要务。地中海盆地自中新世（Miocene）以来经历了显著的气候变化，这些变化极大地影响了地中海植物区系的演化。本研究聚焦于两类局限于西地中海盆地的薹草姊妹物种（薹草属Carex，莎草科Cyperaceae），该类群在中欧曾发现有上新世（Pliocene）的化石记录。具体而言，我们估算了气候生态位随时间的演化过程及其对谱系分化的影响。本研究基于7个DNA区域（核DNA nDNA与质体DNA ptDNA）及指纹图谱数据（扩增片段长度多态性AFLPs）开展了带年代校准的系统发育-系统地理学研究，并针对上新世、更新世（Pleistocene）及现代三个时期构建了生态位与物种分布模型。系统发育与分化时间分析结果显示，这两个物种构成一个单系谱系，其起源时间可追溯至上新世晚期-更新世早期。我们在两个物种的间断分布区内检测到了清晰的遗传分化与显著的遗传聚类结构，表明地理屏障在限制基因流方面发挥了主导作用。研究发现，上新世种群与现存种群的气候需求发生了显著变化；不过自两个物种于更新世发生分化以来，其气候生态位始终保持相对保守。本研究凸显了整合包括化石数据在内的多源数据与分析手段的研究路径，可为某一植物类群自上新世以来的演化历史提供可靠且稳健的推论。