The influence of island dynamics and characteristics on taxonomic diversity, particularly species richness, are well studied. Yet, our knowledge on the influence of island dynamics and characteristics on other facets of diversity, namely functional and phylogenetic diversity, is limited, constraining our understanding of assembly processes on islands (e.g. biogeographic history, dispersal and environmental filtering and species interactions). Using barrier islands, a highly dynamic and so far, understudied island type, we investigate how multiple facets of vascular plant diversity (functional, phylogenetic and taxonomic diversity) are shaped by island geomorphology, modern and historic area, and habitat heterogeneity. In line with our expectation, historical dynamics in island geomorphology affected phylogenetic and taxonomic diversity via habitat heterogeneity. However, island area was the best predictor across all facets of diversity. Specifically, larger islands had higher functional and phylogenetic diversity than expected by chance while most of the smaller islands had lower diversity. The influence of area on functional diversity acted via habitat heterogeneity, with habitat heterogeneity influencing negatively functional diversity. Our results suggest that larger islands accumulate functionally and phylogenetically unique species. Further, results for functional diversity pointed towards potential area–heterogeneity trade-offs, with these trade-offs likely resulting from increased interspecific competition favoring a specific set of trait values (of stronger competitors), particularly on smaller islands. Together, these results demonstrate that going beyond taxonomic diversity contributes to identifying underlying processes shaping diversity–area relationships.

中文翻译：

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岛区和历史地貌动态塑造了障壁岛植物群的多方面多样性

岛屿动态和特征对分类多样性，特别是物种丰富度的影响已得到很好的研究。然而，我们对岛屿动态和特征对多样性其他方面（即功能和系统发育多样性）的影响的了解有限，这限制了我们对岛屿组装过程（例如生物地理历史、扩散和环境过滤以及物种相互作用）的理解。使用障碍岛，一种高度动态且迄今为止未被充分研究的岛屿类型，我们研究了维管植物多样性（功能、系统发育和分类多样性）的多个方面如何受岛屿地貌、现代和历史区域以及栖息地异质性的影响。符合我们的预期，岛屿地貌的历史动态通过栖息地异质性影响系统发育和分类多样性。然而，岛屿面积是多样性所有方面的最佳预测指标。具体来说，较大的岛屿具有比偶然预期更高的功能和系统发育多样性，而大多数较小的岛屿具有较低的多样性。面积对功能多样性的影响通过生境异质性起作用，生境异质性对功能多样性产生负面影响。我们的研究结果表明，较大的岛屿在功能和系统发育上积累了独特的物种。此外，功能多样性的结果指向潜在的区域异质性权衡，这些权衡可能是由于种间竞争的增加有利于（更强大的竞争对手的）一组特定的特征值，特别是在较小的岛屿上。总之，这些结果表明，超越分类多样性有助于确定塑造多样性 - 区域关系的潜在过程。