Variation in plant dispersal capabilities strongly influences the assembly of island plant communities. Many tropical plants have seeds capable of long-distance, often oceanic, dispersal; in some cases, these taxa speciate into island interior endemics with reduced dispersal capabilities, though whether this is a general pattern is debated. Flotation times are highly variable among plants with oceanic dispersal and between such plants and their inland congeners. Here, we experimentally compared salt-water flotation in three woody plant genera in Palau, Micronesia, comparing broadly distributed and island endemic species within each genus. The widespread Calophyllum inophyllum (with oceanic and vertebrate dispersal), C. soulattri (vertebrate dispersal), and Terminalia catappa had substantially longer flotation than their inland endemic relatives C. pelewense and T. crassipes. This supports the “Loss of dispersal ability” hypothesis for Calophyllum though, for Terminalia, additional phylogenetic information is needed to determine T. crassipes' sister species. Seed flotation in the widespread, oceanic dispersed Pandanus tectorius did not significantly differ from that of the Palau endemics P. palawensis and P. aimiriikensis. Our results highlight that differences among taxa in dispersal modes, speciation modes, and their interactions may influence the assembly of island floras.

中文翻译：

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一些广泛分布于海洋的树木及其岛屿特有同源植物的种子漂浮

植物传播能力的变化强烈影响岛屿植物群落的聚集。许多热带植物的种子能够远距离（通常是海洋）传播；在某些情况下，这些类群分化为岛屿内陆特有物种，但扩散能力降低，尽管这是否是普遍模式尚有争议。海洋传播的植物之间以及此类植物与其内陆同类植物之间的漂浮时间差异很大。在这里，我们通过实验比较了密克罗尼西亚帕劳的三个木本植物属的盐水浮选，比较了每个属内广泛分布的物种和岛屿特有的物种。广泛分布的Calophyllum inophyllum（在海洋和脊椎动物中传播）、C. Soulattri（在脊椎动物中传播）和Terminalia catappa比它们的内陆特有亲戚C. pelewense和T. crassipes具有更长的漂浮时间。这支持了海藻属的“分散能力丧失”假说，但对于榄仁树来说，需要额外的系统发育信息来确定T. crassipes的姐妹种。广泛分布于海洋的露兜树(Pandanus tectorius) 的种子漂浮能力与帕劳特有种露兜树(P. palawensis)和P. aimiriikensis的种子漂浮能力没有显着差异。我们的结果强调，类群之间在扩散模式、物种形成模式及其相互作用方面的差异可能会影响岛屿植物群的聚集。