High species richness and endemism in tropical mountains are recognized as major contributors to the latitudinal diversity gradient. The processes underlying mountain speciation, however, are largely untested. The prevalence of steep ecogeographic gradients and the geographic isolation of populations by topographic features are predicted to promote speciation in mountains. We evaluate these processes in a species‐rich Neotropical genus of understory herbs that range from the lowlands to montane forests and have higher species richness in topographically complex regions. We ask whether climatic niche divergence, geographic isolation, and pollination shifts differ between mountain‐influenced and lowland Amazonian sister pairs inferred from a 756‐gene phylogeny. Neotropical Costus ancestors diverged in Central America during a period of mountain formation in the last 3 million years with later colonization of Amazonia. Although climatic divergence, geographic isolation, and pollination shifts are prevalent in general, these factors do not differ between mountain‐influenced and Amazonian sister pairs. Despite higher climatic niche and species diversity in the mountains, speciation modes in Costus appear similar across regions. Thus, greater species richness in tropical mountains may reflect differences in colonization history, diversification rates, or the prevalence of rapidly evolving plant life forms, rather than differences in speciation mode.

中文翻译：

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新热带植物辐射（Costaceae：Costus）的物种形成模式在山区和低地地区相似

热带山区的高物种丰富度和特有性被认为是造成纬度多样性梯度的主要因素。然而，山地物种形成背后的过程在很大程度上未经测试。陡峭的生态地理梯度的盛行和地形特征对种群的地理隔离预计将促进山区的物种形成。我们在物种丰富的新热带林下草本属中评估了这些过程，这些草本植物范围从低地到山地森林，并且在地形复杂的地区具有更高的物种丰富度。我们询问从 756 基因系统发育推断的受山区影响和低地亚马逊姐妹对之间的气候生态位差异、地理隔离和授粉转移是否不同。新热带 Costus 的祖先在过去 300 万年的山脉形成期间在中美洲分流，后来又在亚马逊河上进行了殖民。尽管气候差异、地理隔离和授粉转移普遍存在，但这些因素在受山区影响的姐妹对和亚马逊姐妹对之间没有区别。尽管山区的气候生态位和物种多样性更高，但科斯塔斯的物种形成模式在不同地区似乎相似。因此，热带山区的物种丰富度可能反映了殖民历史、多样化率或快速进化的植物生命形式普遍存在的差异，而不是物种形成模式的差异。授粉变化普遍普遍，但这些因素在受山区影响的姐妹对和亚马逊姐妹对之间没有区别。尽管山区的气候生态位和物种多样性更高，但科斯图斯的物种形成模式在不同地区似乎相似。因此，热带山区的物种丰富度可能反映了殖民历史、多样化率或快速进化的植物生命形式普遍存在的差异，而不是物种形成模式的差异。授粉变化普遍普遍，但这些因素在受山区影响的姐妹对和亚马逊姐妹对之间没有区别。尽管山区的气候生态位和物种多样性更高，但科斯塔斯的物种形成模式在不同地区似乎相似。因此，热带山区的物种丰富度可能反映了殖民历史、多样化率或快速进化的植物生命形式普遍存在的差异，而不是物种形成模式的差异。