LARGE‐SCALE PATTERNS OF DIVERSIFICATION IN THE WIDESPREAD LEGUME GENUS SENNA AND THE EVOLUTIONARY ROLE OF EXTRAFLORAL NECTARIES
LARGE‐SCALE PATTERNS OF DIVERSIFICATION IN THE WIDESPREAD LEGUME GENUS SENNA AND THE EVOLUTIONARY ROLE OF EXTRAFLORAL NECTARIES
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DOI：
10.1111/j.1558-5646.2010.01086.x
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发表时间：
2010-12
期刊：
影响因子：
3.3
通讯作者：
Brigitte Marazzi;M. Sanderson
中科院分区：
文献类型：
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作者：
Brigitte Marazzi;M. Sanderson
由于灭绝、采样不足和分类学的不确定性，解开古老、物种丰富和广泛的分支的多样化历史是困难的。在这些挑战的背景下，我们调查的时间和模式的血统多样化的番泻叶（豆科植物），以深入了解花外蜜腺（EFN）的进化作用。EFN分泌花蜜，吸引蚂蚁并形成生态上重要的蚂蚁-植物互惠关系。在番泻叶中，EFN表征一个大分支（EFN分支），包括其350种的80%。分类学的帐户使番泻叶最大的caesalpinioid属，但定量比较其他类群需要推断率。分子测年分析表明，番泻叶起源于始新世早期，其主要谱系出现在早/中始新世至早渐新世。EFN演化于始新世晚期，在蚂蚁的主要辐射之后。EFN分支多样化更快，比非EFN分支物种丰富得多。与EFN演变相关的多样化率的变化支持了EFN代表塞纳（相对古老）关键创新的假设。EFN可能促进了新栖息地的殖民化，这些新栖息地是随着安第斯山脉的早期隆起而出现的。这可以解释为什么EFN分支在南美洲的独特地理集中。
Unraveling the diversification history of old, species‐rich and widespread clades is difficult because of extinction, undersampling, and taxonomic uncertainty. In the context of these challenges, we investigated the timing and mode of lineage diversification in Senna (Leguminosae) to gain insights into the evolutionary role of extrafloral nectaries (EFNs). EFNs secrete nectar, attracting ants and forming ecologically important ant–plant mutualisms. In Senna, EFNs characterize one large clade (EFN clade), including 80% of its 350 species. Taxonomic accounts make Senna the largest caesalpinioid genus, but quantitative comparisons to other taxa require inferences about rates. Molecular dating analyses suggest that Senna originated in the early Eocene, and its major lineages appeared during early/mid Eocene to early Oligocene. EFNs evolved in the late Eocene, after the main radiation of ants. The EFN clade diversified faster, becoming significantly more species‐rich than non‐EFN clades. The shift in diversification rates associated with EFN evolution supports the hypothesis that EFNs represent a (relatively old) key innovation in Senna. EFNs may have promoted the colonization of new habitats appearing with the early uplift of the Andes. This would explain the distinctive geographic concentration of the EFN clade in South America.