Alpine plant radiations are common across all major mountain systems of the world, and have been regarded as the main explanation for the species diversity found within these areas. To study the mechanisms behind the origin of this diversity, it is necessary to determine phylogenetic relationships and species boundaries in radiating alpine groups. The genus Dendrosenecio (Asteraceae) is an iconic example of a tropical-alpine plant radiation in the East African high mountains. To this date, limited sampling of molecular markers has resulted in insufficient phylogenetic resolution and infrageneric classification, hindering a comprehensive understanding of the drivers of diversification. Here, we used Hyb-Seq and the Compositae1061 probe set to generate targeted nuclear and off-target plastid DNA data for 42 samples representing all currently accepted 11 species. We combined coalescent methods and paralogy analysis to infer phylogenetic relationships, estimate divergence times and evaluate species boundaries. Lineage differentiation in Dendrosenecio seems to have occurred between the Late Miocene and the Pleistocene, starting when the first high elevation habitats became available in East Africa. We retrieved four major clades corresponding to four geographically distant mountain groups, testifying the importance of allopatric speciation in the early diversification of the group. Cytonuclear discordance suggested the occurrence of historical hybridization following occasional long-distance dispersal between mountain groups. The species delimitation analysis favored 10 species, but only five were fully supported, suggesting that population-level studies addressing processes such as ecological speciation and hybridization after secondary contact are needed to determine the current diversity found in the genus.

高山植物辐射在世界所有主要山区系统中都很常见，并被认为是这些地区发现的物种多样性的主要解释。为了研究这种多样性起源背后的机制，有必要确定辐射高山群体的系统发育关系和物种边界。石竹属（菊科）是东非高山热带高山植物辐射的标志性例子。迄今为止，分子标记的有限采样导致系统发育分辨率和属下分类不足，阻碍了对多样化驱动因素的全面了解。在这里，我们使用 Hyb-Seq 和 Comppositae1061 探针组为代表所有当前接受的 11 个物种的 42 个样本生成靶向核和脱靶质体 DNA 数据。我们结合合并方法和旁系分析来推断系统发育关系，估计分歧时间并评估物种边界。Dendrosenecio的谱系分化似乎发生在晚中新世和更新世之间，从东非第一个高海拔栖息地出现时开始。我们检索到了对应于四个地理上遥远的山脉群的四个主要进化枝，证明了异域物种形成在该群体早期多样化中的重要性。细胞核不一致表明，在山地群体之间偶尔进行长距离分散后，历史上发生了杂交。物种界定分析有利于 10 个物种，但只有 5 个物种得到完全支持，这表明需要针对二次接触后的生态物种形成和杂交等过程进行种群水平研究，以确定该属目前的多样性。