A large number of studies have attempted to determine the mechanisms driving plant diversity and distribution on a global scale, but the diverse and endemic alpine herbs found in harsh environments, showing adaptive evolution, require more studies. Here, we selected 466 species from the genus Saussurea, one of the northern hemisphere’s highest-altitude plant genera with high species richness and striking morphological traits, to explore the mechanisms driving speciation and adaptative evolution. We conducted phylogenetic signals analysis and ancestral character estimation to explore the phylogenetic significance of ecological factors. Moreover, we used spatial simultaneous autoregressive (SAR) error models, modified t-tests and partial regression models to quantify the relative effects of ecological factors and morphological diversity upon diversity and endemism of Saussurea. Phylogenetic analyses reveal that geological influences and climate stability exhibit significant phylogenetic signals and that Saussurea originated at a relatively high elevation. Regression models indicate that geological influences and climatic stability significantly affect the diversity and endemism patterns of Saussurea and its morphological innovations. Moreover, morphological innovations in an area show significant contributions to the local diversity and endemism of Saussurea. We conclude that geological influences (mean altitude and topographic heterogeneity), glacial–interglacial climate stability and phylogenetic conservatism have together promoted the speciation and adaptive evolution of the genus Saussurea. In addition, adaptively morphological innovations of alpine species also promote diversification in local regions. Our findings improve the understanding of the distribution pattern of diversity/endemism and adaptive evolution of alpine specie in the whole northern hemisphere.

中文翻译：

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高山物种形成和形态学创新：来自北半球物种丰富属的启示

大量研究试图确定在全球范围内推动植物多样性和分布的机制，但在恶劣环境中发现的多样性和地方性高山草本植物显示出适应性进化，需要更多的研究。在这里，我们从北半球海拔最高的植物属之一的雪莲属中选择了 466 个物种，具有高物种丰富度和显着的形态特征，以探索驱动物种形成和适应性进化的机制。我们进行了系统发育信号分析和祖先特征估计，以探索生态因素的系统发育意义。此外，我们使用空间同时自回归 (SAR) 误差模型，修正 t 检验和偏回归模型以量化生态因素和形态多样性对雪莲的多样性和特有性的相对影响。系统发育分析表明，地质影响和气候稳定性表现出显着的系统发育信号，并且雪莲起源于相对较高的海拔。回归模型表明，地质影响和气候稳定性显着影响雪莲的多样性和特有模式及其形态创新。此外，一个地区的形态学创新对雪莲的当地多样性和特有性有显着贡献。我们得出结论，地质影响（平均海拔和地形异质性），冰-间冰期气候稳定性和系统发育保守性共同促进了雪莲属的物种形成和适应性进化。此外，高山物种的适应性形态创新也促进了当地的多样化。我们的研究结果提高了对整个北半球高山物种多样性/特有性分布模式和适应性进化的理解。