Why are there so many sedges? Sumatroscirpeae, a missing piece in the evolutionary puzzle of the giant genus Carex (Cyperaceae)
Why are there so many sedges? Sumatroscirpeae, a missing piece in the evolutionary puzzle of the giant genus Carex (Cyperaceae)
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DOI：
10.1016/j.ympev.2017.10.025
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发表时间：
2018-02-01
影响因子：
4.1
通讯作者：
Ford, Bruce A.
中科院分区：
文献类型：
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作者：
Leveille-Bourret, Etienne;Starr, Julian R.;Ford, Bruce A.
一个多世纪以来，巨大的温带苔草属(>；2100种；Cariceae，莎草科)多样性的起源和机制在很大程度上仍然是推测的。其多样的生态、多样的生物地理和有趣的细胞学等特点使Carex成为研究植物进化的强大模型，但其不确定的姐妹群关系阻碍了其在依赖准确的祖先状态估计和生物地理推断的研究中的应用。为了鉴定苔草属的姊妹种，我们利用3个叶绿体和2个核糖体标记对Cariceae-Dulichieae-SCirpeae分支(CDS)中所有属的系统发育进行了估计。对关键人物的祖先状态进行了重建，并估计了一棵经过时间校准的树。苔草是稀有的东亚华夏的姊妹种，是一个新部落-华夏的唯一属。11月被认为是苔草独有的外胚层(包围一朵花的叶柄)实际上是一个与这个小部落(类似于4个物种)共享的同形突触，出现了36Mya。因此，我们认为，Carex显著多样化的最初关键创新不是骨膜，而可能是通过小穗截断释放对骨膜的机械约束，从而产生新的适应性形态。单性生殖、染色体变化和花序的快速发育也可能导致物候隔离。这个小小的SumtresCirpeae部落将提供前所未有的见解，了解其姊妹种群苔草的花序同源性、进化、多样性和生物地理历史。苔草是世界上最多样化的植物谱系之一。
For over a century, the origins and mechanisms underlying the diversification of the enormous temperate genus Carex (> 2100 species; Cariceae, Cyperaceae) have remained largely speculative. Characteristics such as its diverse ecology, varied biogeography, and intriguing cytology have made Carex a powerful model for studying plant evolution, but its uncertain sister-group relationships hinder its use in studies that depend on accurate ancestral state estimates and biogeographic inferences. To identify the sister to Carex, we estimated the phylogeny of all genera in the Cariceae-Dulichieae-Scirpeae clade (CDS) using three plastid and two nuclear ribosomal markers. Ancestral state reconstructions of key characters were made, and a time-calibrated tree estimated. Carex is strongly supported as sister to the rare East Asian Sumatroscirpus, sole genus of a new tribe, Sumatroscirpeae trib. nov. Believed to be unique to Carex, the perigynium (prophyllar bract enclosing a flower) is in fact a synapomorphy shared with this small tribe (similar to 4 species) that appeared 36 Mya. We thus suggest the initial key innovation in the remarkable diversification of Carex is not the perigynium, but could be the release of mechanical constraints on perigynia through spikelet truncation, resulting in novel adaptive morphologies. Monoecy, chromosomal change, and rapid inflorescence development enabling phenological isolation may also be involved. The tiny tribe Sumatroscirpeae will provide unprecedented insights into the inflorescence homology, evolution, diversification, and biogeographic history of its sister-group Carex, one of the world's most diverse plant lineages.