Contrasting patterns of phylogenetic diversity and alpine specialization across the alpine flora of the American mountain range system

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 comprehensive dataset that characterized the elevational niches of American seed plants in a continuously valued way, we were able to quantitatively investigate how the proportion of alpine habitat occupied by plants related 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 sites with lower phylogenetic diversity contained species with a greater degree of alpine specialization. In particular, near Arctic/ boreal alpine communities were charact...

尽管山地生境对全球生物多样性贡献显著，但目前学界对跨多个山脉的高山物种（alpine species）分布的生物地理格局（biogeographic patterns）认知仍相对匮乏。本研究针对北美、中美及南美山地系统内的高山种子植物支系的分布与系统发育亲缘关系（phylogenetic affinities）展开了详尽分析。本研究依托一套以连续量化方式刻画美洲种子植物海拔生态位（elevational niches）的综合数据集，得以在区域尺度上定量探究植物占据的高山生境比例与其生物地理分布之间的关联，并将研究结果置于系统发育框架下进行解读。研究发现，高山物种多样性在安第斯山脉中部与北美西部达到峰值；而系统发育多样性（phylogenetic diversity）较低的区域，其物种的高山特化程度更高。尤为值得关注的是，北极/寒温带（boreal）周边的高山群落具有……