Complex evolutionary history of two ecologically significant grass genera, Themeda and Heteropogon (Poaceae: Panicoideae: Andropogoneae)
Complex evolutionary history of two ecologically significant grass genera, Themeda and Heteropogon (Poaceae: Panicoideae: Andropogoneae)
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DOI：
10.1093/botlinnean/boab008
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发表时间：
2021-03-09
影响因子：
2.4
通讯作者：
Vorontsova, Maria S.
中科院分区：
文献类型：
--
作者：
Arthan, Watchara;Dunning, Luke T.;Vorontsova, Maria S.
Themeda和Heteropogon是密切相关的草属，在热带C-4草原中经常占优势。它们之间的关系还没有得到很好的解决，阻碍了生态学研究，特别是T。triandra广泛分布于非洲至东亚，H.具有泛热带分布的扭体鱼。我们的质体和核基因组的全面采样Themeda和Heteropogon的分析表明，这两个属是单系的，目前限制。质体组和核数据将H. melanocarpus和H.在特米达的里奇嵌套在T. triandra是T. quadrivalvis和T. unica，表明这一广泛分布的物种在形态上比以前认识到的更多样化。Heteropogon fischerianus是H.扭曲对于H来说，情况要复杂得多。triticeus是H.在细胞核分析中与捻转草属相似，在质体分析中与香茅属相似。核和质体系统发育树之间的这种不一致表明Cymbopogon相关基因组供体和H。扭曲Plastome测年估计Themeda-Heteropogon冠年龄在c。7.6 Myr，与中新世C-4草原扩张一致。Themeda triandra和H. contortus在更新世分化了1-2万年。这些结果为研究这些具有重要生态意义的广布禾本科植物及其形成的生态系统的历史奠定了基础。
Themeda and Heteropogon are closely related grass genera frequently dominant in tropical C-4 grasslands. Relationships between them are poorly resolved, impeding ecological study, especially of T. triandra with a broad distribution from Africa to East Asia, and H. contortus with a pantropical distribution. Our analyses of plastome and nuclear genomes with comprehensive sampling of Themeda and Heteropogon demonstrate that neither genus is monophyletic as currently circumscribed. Plastome and nuclear data place H. melanocarpus and H. ritchiei in Themeda. Nested in T. triandra are T. quadrivalvis and T. unica, demonstrating that this widespread species is more morphologically diverse than previously recognized. Heteropogon fischerianus is nested in H. contortus. The picture is more complex for H. triticeus that is sister to H. contortus in the nuclear analysis and to Cymbopogon in the plastome analysis. This incongruence between nuclear and plastid phylogenetic trees suggests hybridization between Cymbopogon-related genome donors and H. contortus. Plastome dating estimates the Themeda-Heteropogon crown age at c. 7.6 Myr, consistent with the Miocene C-4 grassland expansion. Themeda triandra and H. contortus diversified 1-2 Mya in the Pleistocene. These results establish a foundation for studying the history of these ecologically significant widespread grasses and the ecosystems they form.