The relationship between global trait distinctiveness and geographic range size is an emerging pattern of interest in macroecology. Early observations suggested that the relationship was positive, implying that globally widespread species hold the rarest combinations of traits. Here, we formally describe and test the relationship in the world's birds and consider its implications for global functional diversity and redundancy. We demonstrate that the relationship is best described as triangular with a positive upper boundary, with its linear model significance lost when including phylogenetic effects. The triangular relationship is formed by groups of phylogenetically related widespread species with moderate and high trait distinctiveness. Decomposing the relationship further using quantile regression highlights the unique traits of these widespread birds. Overall, the triangular relationship emphasises that while not all widespread species have rare trait combinations, those that do should not be overlooked in conservation efforts, regardless of their current threat status.

中文翻译：

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全球鸟类的功能多样性取决于世界上最广泛和最独特的鸟类


全球性状独特性与地理范围大小之间的关系是宏观生态学中一种新兴的兴趣模式。早期观察表明，这种关系是积极的，这意味着全球分布的物种拥有最稀有的性状组合。在这里，我们正式描述和测试了世界鸟类之间的关系，并考虑了它对全球功能多样性和冗余的影响。我们证明，最好将这种关系描述为具有正上边界的三角形，当包括系统发育效应时，其线性模型显着性就丢失了。三角关系是由具有中等和高度性状独特性的系统发育相关的广泛物种群形成的。使用分位数回归进一步分解关系突出了这些广泛分布的鸟类的独特特征。总体而言，三角关系强调，虽然并非所有广泛分布的物种都具有稀有的特征组合，但在保护工作中不应忽视那些具有稀有特征组合的物种，无论它们目前的威胁状况如何。