Biogeography and genome size evolution of the oldest extant vascular plant genus, Equisetum (Equisetaceae)
Biogeography and genome size evolution of the oldest extant vascular plant genus, Equisetum (Equisetaceae)
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DOI：
10.1093/aob/mcab005
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发表时间：
2021-04-09
期刊：
影响因子：
4.2
通讯作者：
Viruel, Juan
中科院分区：
文献类型：
--
作者：
Christenhusz, Maarten J. M.;Chase, Mark W.;Viruel, Juan
研究背景和目的具有悠久化石历史的现存植物类群是了解维管植物进化的关键要素。马尾（木贼，木贼科）有一个几乎连续的化石记录可以追溯到石炭纪，但他们的系统发育和地理模式仍然知之甚少。我们在这里使用最广泛的系统发育分析作为一个框架，以评估其年龄，地理和基因组大小evolution.Methods DNA序列的四个质体位点的DNA序列估计分歧时间和调查所有现存种木贼的地理历史。流式细胞仪被用来研究基因组大小的进化对框架的系统发育关系在Equisetum.Key结果在一个良好的支持系统发育树，包括所有现存的木贼物种，一个分子时钟校准与多个化石的地方节点，在该节点处的外群和木贼分歧在343万年（早石炭世），与现存物种之间的第一个主要分裂发生170万年（中侏罗世）。这些日期比其他一些最近的分子钟研究报告的日期要早，但与地质记录中化石外观建立的时间轴基本一致。万年青亚属的代表有更大的基因组大小比落叶亚属木贼，尽管他们共享保守的染色体数目。亚属Paramochaete有一个中间的基因组大小，并保持相同数目的chromosome.Conclusions属现存成员之间的第一分歧正好与泛古陆的分裂，从而导致更潮湿，更温暖的气候。随后的构造活动最有可能涉及的vicariance事件，导致物种的分歧结合一些最近的，长距离的传播事件。我们推测亚属之间基因组大小的差异可能与精子鞭毛的数量有关。
Background and Aims Extant plant groups with a long fossil history are key elements in understanding vascular plant evolution. Horsetails (Equisetum, Equisetaceae) have a nearly continuous fossil record dating back to the Carboniferous, but their phylogenetic and biogeographic patterns are still poorly understood. We use here the most extensive phylogenetic analysis to date as a framework to evaluate their age, biogeography and genome size evolution.Methods DNA sequences of four plastid loci were used to estimate divergence times and investigate the biogeographic history of all extant species of Equisetum. Flow cytometry was used to study genome size evolution against the framework of phylogenetic relationships in Equisetum.Key Results On a well-supported phylogenetic tree including all extant Equisetum species, a molecular clock calibrated with multiple fossils places the node at which the outgroup and Equisetum diverged at 343 Mya (Early Carboniferous), with the first major split among extant species occurring 170 Mya (Middle Jurassic). These dates are older than those reported in some other recent molecular clock studies but are largely in agreement with a timeline established by fossil appearance in the geological record. Representatives of evergreen subgenus Hippochaete have much larger genome sizes than those of deciduous subgenus Equisetum, despite their shared conserved chromosome number. Subgenus Paramochaete has an intermediate genome size and maintains the same number of chromosomes.Conclusions The first divergences among extant members of the genus coincided with the break-up of Pangaea and the resulting more humid, warmer climate. Subsequent tectonic activity most likely involved vicariance events that led to species divergences combined with some more recent, long-distance dispersal events. We hypothesize that differences in genome size between subgenera may be related to the number of sperm flagellae.