Assemblages in seasonal ecosystems undergo striking changes in species composition and diversity across the annual cycle. Despite a long‐standing recognition that seasonality structures biogeographic gradients in taxonomic diversity (e.g., species richness), our understanding of how seasonality structures other aspects of biodiversity (e.g., functional diversity) has lagged. Integrating seasonal species distributions with comprehensive data on key morphological traits for bird assemblages across North America, we find that seasonal turnover in functional diversity increases with the magnitude and predictability of seasonality. Furthermore, seasonal increases in bird species richness led to a denser packing of functional trait space, but functional expansion was important, especially in regions with higher seasonality. Our results suggest that the magnitude and predictability of seasonality and total productivity can explain the geography of changes in functional diversity with broader implications for understanding species redistribution, community assembly and ecosystem functioning.

中文翻译：

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季节性结构：北美鸟类功能多样性和生态位包装


季节性生态系统中的组合在年度周期中，物种组成和多样性发生了显着变化。尽管人们长期以来一直认识到季节性构成了分类多样性（例如物种丰富度）的生物地理梯度，但我们对季节性如何构建生物多样性其他方面（例如功能多样性）的理解却滞后了。将季节性物种分布与北美鸟类组合关键形态特征的综合数据相结合，我们发现功能多样性的季节性更替随着季节性的大小和可预测性而增加。此外，鸟类物种丰富度的季节性增加导致功能性状空间的密集堆积，但功能扩展很重要，尤其是在季节性较高的地区。我们的结果表明，季节性和总生产力的大小和可预测性可以解释功能多样性变化的地理学，对理解物种再分布、群落组装和生态系统功能具有更广泛的意义。