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 My 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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对于新热带植物辐射，山区和低地地区的物种形成模式相似（肋骨科：Cotus）

热带山区的高度物种丰富性和地方性被认为是造成纬度多样性梯度的主要因素。但是，山区物种形成的基本过程尚未经过测试。预计陡峭的生态地理梯度的盛行和按地形特征对人口的地理隔离将促进山区的物种形成。我们评估了这些植物在低地种到山地森林等地底植物种类丰富的新热带属中的作用，这些植物在地形复杂的地区具有较高的物种丰富度。我们询问从756个基因的系统发育学推断的受山地影响和低陆的亚马逊姐妹对之间的气候位差异，地理隔离和授粉转移是否不同。新热带肋骨在前3 My的山区形成时期中，祖先在中美洲出现分歧，后来对亚马逊河定居。尽管总体上普遍存在气候差异，地理隔离和授粉移动，但是在受山地影响的亚马逊对和亚马逊姐妹对之间，这些因素并没有不同。尽管山区有较高的气候生态位和物种多样性，但科斯塔斯的物种形成模式在各个地区似乎都相似。因此，热带山区物种丰富度的增加可能反映了殖民历史，多样化率或快速发展的植物生命形式的普遍性，而不是物种形成方式的差异。