Metrosideros (Myrtaceae) comprises 58 woody species distributed across Oceania and with three singleton outliers in Philippines, South America and Africa. Centres of species richness occur in New Zealand and New Caledonia. This distribution accords with a proposed Gondwanan origin for the family. While the phylogeography of one component of the genus – subgenus Metrosideros – has received some examination, the rest of the genus has not been resolved. In this study, we improve resolution of the phylogeny of Metrosideros and consider origin, possible vicariant relationships, long-distance dispersal events and dispersal routes for the genus. A Bayesian phylogeny, with all but one recently described species of Metrosideros, was constructed using concatenated ITS + ETS rDNA from samples we collected and sequenced. Relative to previous work on Metrosideros using ITS alone, here, using ITS plus ETS, we produce a more detailed and robust phylogeny with a near threefold increase in significant nodal support. Putative centres of origin/diversification, vicariant events and dispersals were considered with reference to the phylogeny, present-day diversity and fossil record of Metrosideros. Metrosideros occurs as five clades, including the former genera Tepualia and Carpolepis. The paraphyletic and now superseded subgenus Mearnsia included elements of four of these clades, whereas subgenus Metrosideros forms a single clade with robust support. Our phylogeography indicates multiple dispersal/vicariant events within the history of the genus, a number of which involved New Zealand. Among other such events, we infer an exceptional 6300 km trans-equatorial dispersal from Fiji to the Bonin Islands (Japan). Australia and New Zealand, respectively, are the likely landmasses of origin and diversification for Metrosideros. Typical patterns of floral dispersal proceed from large continental landmasses onto increasingly remote islands and with distance from continent species diversity usually declines. However, Metrosideros shows a countervailing pattern since relatively remote islands are the main centres of speciation and dispersal.

中文翻译：

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大洋洲的桃金娘科：起源、进化和传播

Metrosideros（桃金娘科）包括分布在大洋洲的 58 种木本物种，在菲律宾、南美洲和非洲有 3 个单例异常值。物种丰富的中心位于新西兰和新喀里多尼亚。这种分布符合该家族提出的冈瓦纳起源。虽然该属的一个组成部分 - 亚属Metrosideros -的系统地理学已经接受了一些检查，但该属的其余部分尚未解决。在这项研究中，我们提高了Metrosideros系统发育的分辨率，并考虑了该属的起源、可能的替代关系、长距离传播事件和传播途径。贝叶斯系统发育，除了最近描述的一种Metrosideros, 是使用来自我们收集和测序的样本的串联 ITS + ETS rDNA 构建的。相对于之前单独使用 ITS在Metrosideros上的工作，在这里，使用 ITS 加 ETS，我们产生了更详细和强大的系统发育，显着节点支持增加了近三倍。参考Metrosideros的系统发育、现代多样性和化石记录，考虑了假定的起源/多样化中心、替代事件和扩散。Metrosideros有五个进化枝，包括前属Tepualia和Carpolepis。并系和现在被取代的亚属Mearnsia包括四个这些进化枝的元素，而亚属Metrosideros形成了一个具有强大支持的单一进化枝。我们的系统地理学表明该属历史上有多次扩散/替代事件，其中一些涉及新西兰。在其他此类事件中，我们推断出从斐济到博宁群岛（日本）的 6300 公里跨赤道异常扩散。澳大利亚和新西兰可能分别是Metrosideros的起源地和多样化的陆地。典型的花卉传播模式从大片大陆开始到越来越偏远的岛屿，随着距离大陆的距离越来越远，物种多样性通常会下降。然而，由于相对偏远的岛屿是物种形成和扩散的主要中心，Metrosideros显示出一种抵消模式。