Human activities have altered the species composition of assemblages through introductions and extinctions, but it remains unclear how those changes can affect the different facets of biodiversity. Here we assessed the impact of changes in species composition on taxonomic, functional, and phylogenetic diversity across 281 bird assemblages worldwide. To provide a more nuanced understanding of functional diversity, we distinguished morphological from life-history traits. We showed that shifts in species composition could trigger a global decline in avian biodiversity due to the high number of potential extinctions. Moreover, these extinctions were not random but unique in terms of function and phylogeny at the regional level. Our findings demonstrated that non-native species cannot compensate for these losses, as they are both morphologically and phylogenetically close to the native fauna. In the context of the ongoing biodiversity crisis, such alterations in the functional and phylogenetic structure of bird assemblages could heighten ecosystem vulnerability.

中文翻译：

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非本地物种和受威胁物种对鸟类组合形态、生活史和系统发育多样性的影响对比

人类活动通过引入和灭绝改变了组合的物种组成，但目前尚不清楚这些变化如何影响生物多样性的不同方面。在这里，我们评估了物种组成的变化对全球 281 个鸟类组合的分类、功能和系统发育多样性的影响。为了更细致地理解功能多样性，我们区分了形态特征和生活史特征。我们发现，由于大量潜在灭绝事件，物种组成的变化可能会引发全球鸟类生物多样性下降。此外，这些灭绝不是随机的，而是在区域层面的功能和系统发育方面是独特的。我们的研究结果表明，非本地物种无法弥补这些损失，因为它们在形态和系统发育上都与本地动物群接近。在持续的生物多样性危机的背景下，鸟类组合功能和系统发育结构的这种改变可能会加剧生态系统的脆弱性。