Although mountainous habitats contribute substantially to global biodiversity, comparatively little is known about biogeographic patterns of distributions of alpine species across multiple mountain ranges. Here, we present a detailed analysis of the distributions and phylogenetic affinities of alpine seed plant lineages across North, Central, and South American mountain systems. Using a large dataset that characterizes the elevational niches of American seed plants in a continuously valued way, we related the proportion of alpine habitat occupied by plant lineages to their biogeographic distributions at a regional scale and place these results in a phylogenetic context. We found alpine species diversity to be greatest in the central Andes and western North America, and that assemblages with lower phylogenetic diversity contained species with a greater degree of alpine specialization. In particular, near-Arctic/boreal alpine communities were characterized by low phylogenetic diversity and higher degrees of alpine specialization, whereas the opposite was observed for southern Patagonian communities. These results suggest that abiotic filtering alone in these climatically similar regions is unlikely to explain alpine community assembly. Nevertheless, the overall relative rarity of alpine specialists, and the tendency for such specialists to be most closely related to montane lineages, suggested that filtering was still an important factor in shaping alpine community structure. This work corroborates the importance of a nuanced and scale-dependent perspective on the ‘history-filtering’ debate axis, as both factors have likely contributed to modern biodiversity patterns observed in alpine plant communities across the Americas.

尽管山区栖息地对全球生物多样性做出了重大贡献，但对跨越多个山脉的高山物种分布的生物地理模式知之甚少。在这里，我们详细分析了北美洲、中美洲和南美洲山区系统的高山种子植物谱系的分布和系统发育亲和力。使用以持续评估方式表征美国种子植物海拔生态位的大型数据集，我们将植物谱系占据的高山栖息地的比例与其在区域范围内的生物地理分布相关联，并将这些结果置于系统发育背景中。我们发现安第斯山脉中部和北美西部的高山物种多样性最大，并且系统发育多样性较低的组合包含具有较高高山专业化程度的物种。特别是，近北极/北方高山群落的特点是系统发育多样性低和高山专业化程度较高，而巴塔哥尼亚南部群落则相反。这些结果表明，仅在这些气候相似地区的非生物过滤不太可能解释高山群落的组装。尽管如此，高山专家的总体相对稀有性，以及这些专家与山地血统最密切相关的趋势，表明过滤仍然是塑造高山群落结构的重要因素。这项工作证实了在“历史过滤”辩论轴上的细微差别和尺度相关的观点的重要性，