PDF(Pubmed)
Abstract：
OBJECTIVE: The geographical origin and evolutionary mechanisms underpinning the rich and distinctive New Caledonian flora remain poorly understood. This is attributable to the complex geological past of the island and to the scarcity of well-resolved species-level phylogenies. Here, we infer phylogenetic relationships and divergence times of New Caledonian palms, which comprise 40 species. We use this framework to elucidate the biogeography of New Caledonian palm lineages and to explore how extant species might have formed.
METHODS: A phylogenetic tree including 37 New Caledonian palm species and 77 relatives from tribe Areceae was inferred from 151 nuclear genes obtained by targeted sequencing. Fossil-calibrated divergence times were estimated and ancestral ranges inferred. Ancestral and extant ecological preferences in terms of elevation, precipitation and substrate were compared between New Caledonian sister species to explore their possible roles as drivers of speciation.
RESULTS: New Caledonian palms form four well-supported clades, inside which relationships are well resolved. Our results support the current classification but suggest that Veillonia and Campecarpus should be resurrected and fail to clarify whether Rhopalostylidinae is sister to or nested in Basseliniinae. New Caledonian palm lineages are derived from New Guinean and Australian ancestors, which reached the island through at least three independent dispersal events between the Eocene and Miocene. Palms then dispersed out of New Caledonia at least five times, mainly towards Pacific islands. Geographical and ecological transitions associated with speciation events differed across time and genera. Substrate transitions were more frequently associated with older events than with younger ones.
CONCLUSIONS: Neighbouring areas and a mosaic of local habitats shaped the palm flora of New Caledonia, and the island played a significant role in generating palm diversity across the Pacific region. This new spatio-temporal framework will enable population-level ecological and genetic studies to unpick the mechanisms underpinning New Caledonian palm endemism.
METHODS: A phylogenetic tree including 37 New Caledonian palm species and 77 relatives from tribe Areceae was inferred from 151 nuclear genes obtained by targeted sequencing. Fossil-calibrated divergence times were estimated and ancestral ranges inferred. Ancestral and extant ecological preferences in terms of elevation, precipitation and substrate were compared between New Caledonian sister species to explore their possible roles as drivers of speciation.
RESULTS: New Caledonian palms form four well-supported clades, inside which relationships are well resolved. Our results support the current classification but suggest that Veillonia and Campecarpus should be resurrected and fail to clarify whether Rhopalostylidinae is sister to or nested in Basseliniinae. New Caledonian palm lineages are derived from New Guinean and Australian ancestors, which reached the island through at least three independent dispersal events between the Eocene and Miocene. Palms then dispersed out of New Caledonia at least five times, mainly towards Pacific islands. Geographical and ecological transitions associated with speciation events differed across time and genera. Substrate transitions were more frequently associated with older events than with younger ones.
CONCLUSIONS: Neighbouring areas and a mosaic of local habitats shaped the palm flora of New Caledonia, and the island played a significant role in generating palm diversity across the Pacific region. This new spatio-temporal framework will enable population-level ecological and genetic studies to unpick the mechanisms underpinning New Caledonian palm endemism.
摘要：
目的：支持丰富和独特的新喀里多尼亚植物区系的地理起源和进化机制仍然知之甚少。这归因于该岛复杂的地质历史以及缺乏解决良好的物种级系统发育。这里,我们推断新喀里多尼亚棕榈树的系统发育关系和发散时间，包括40种。我们使用此框架来阐明新喀里多尼亚棕榈谱系的生物地理学，并探索现存物种如何形成。
方法：从通过靶向测序获得的151个核基因中，推断了一个包括37个新喀里多尼亚棕榈物种和77个近缘种的系统进化树。估算了化石校准的发散时间，并推断了祖先的范围。就海拔而言，祖先和现存的生态偏好，比较了新喀里多尼亚姐妹物种之间的降水和底物，以探索它们作为物种形成驱动因素的可能作用。
结果：新喀里多尼亚手掌形成四个支撑良好的进化枝，其中关系得到很好的解决。我们的结果支持当前的分类，但建议应将Veillonia和Campecarpus复活，并且无法澄清Rhopalostylidinae是姐妹还是嵌套在Basseliniinae中。新喀里多尼亚的棕榈血统来自新英格兰和澳大利亚的祖先，它通过始新世和上新世之间的至少三个独立的扩散事件到达了该岛。棕榈随后至少五次从新喀里多尼亚散出，主要是太平洋岛屿。与物种形成事件相关的地理和生态转变因时间和属而异。与较年轻的事件相比，底物转换与较老的事件更频繁地相关。
结论：邻近地区和当地栖息地的马赛克形成了新喀里多尼亚的棕榈植物区系，该岛在整个太平洋地区产生棕榈多样性方面发挥了重要作用。这种新的时空框架将使种群水平的生态和遗传研究能够解开支撑新喀里多尼亚棕榈特有的机制。
方法：从通过靶向测序获得的151个核基因中，推断了一个包括37个新喀里多尼亚棕榈物种和77个近缘种的系统进化树。估算了化石校准的发散时间，并推断了祖先的范围。就海拔而言，祖先和现存的生态偏好，比较了新喀里多尼亚姐妹物种之间的降水和底物，以探索它们作为物种形成驱动因素的可能作用。
结果：新喀里多尼亚手掌形成四个支撑良好的进化枝，其中关系得到很好的解决。我们的结果支持当前的分类，但建议应将Veillonia和Campecarpus复活，并且无法澄清Rhopalostylidinae是姐妹还是嵌套在Basseliniinae中。新喀里多尼亚的棕榈血统来自新英格兰和澳大利亚的祖先，它通过始新世和上新世之间的至少三个独立的扩散事件到达了该岛。棕榈随后至少五次从新喀里多尼亚散出，主要是太平洋岛屿。与物种形成事件相关的地理和生态转变因时间和属而异。与较年轻的事件相比，底物转换与较老的事件更频繁地相关。
结论：邻近地区和当地栖息地的马赛克形成了新喀里多尼亚的棕榈植物区系，该岛在整个太平洋地区产生棕榈多样性方面发挥了重要作用。这种新的时空框架将使种群水平的生态和遗传研究能够解开支撑新喀里多尼亚棕榈特有的机制。
