State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Mol Phylogenet Evol. 2018 Dec;129:106-116. doi: 10.1016/j.ympev.2018.08.011. Epub 2018 Aug 25.
Pinaceae comprises 11 genera, and represents the largest family of conifers with an extensive wild distribution in the Northern Hemisphere. Intergeneric relationships of Pinaceae have been investigated using many morphological characters and molecular markers, but phylogenetic positions of four genera, including Cathaya, Cedrus, Nothotsuga and Pseudolarix, remain controversial or have not been completely resolved. To completely resolve the intergeneric relationships of Pinaceae, we conducted a comparative transcriptomic study of 14 species representing all Pinaceae genera. Multiple data sets, containing up to 6,369,681 sites across 4676 loci, were analyzed using concatenation and coalescent methods. Our study generated a robust topology, which divides Pinaceae into two clades, one (pinoid) including Cathaya, Larix, Picea, Pinus, and Pseudotsuga, and the other (abietoid) including Abies, Cedrus, Keteleeria, Nothotsuga, Pseudolarix, and Tsuga. Cathaya and Pinus form a clade sister to Picea; Cedrus is sister to the remaining abietoid genera, and the two genera Nothotsuga and Tsuga form a clade sister to Pseudolarix. The discordant positions of Cathaya, Cedrus and Pseudolarix in different gene trees could be explained by ancient radiation and/or molecular homoplastic evolution. The hybrid origin hypothesis of Nothotsuga is not supported. Based on molecular dating, extant Pinaceae genera diverged since about 206 Mya, earlier than the break-up of Pangea, and the divergence among the pinoid genera occurred earlier than the split among the abietoid genera. Moreover, our study indicates that two radiation events occurred in the evolution of Pinaceae genera, and some important morphological characters evolved multiple times based on ancestral state reconstruction.
松科包含 11 个属，是北半球分布最广的最大的针叶树科。利用许多形态特征和分子标记研究了松科的属间关系，但包括银杉、雪松、北美乔松和金钱松在内的四个属的系统发育位置仍存在争议或尚未完全解决。为了完全解决松科的属间关系，我们对代表所有松科属的 14 个物种进行了比较转录组研究。使用串联和合并方法分析了多达 6369681 个位点的 4676 个基因座的多个数据集。我们的研究生成了一个稳健的拓扑结构，该结构将松科分为两个分支，一个分支（松型）包括银杉、落叶松、云杉、松属和罗汉松，另一个分支（冷杉型）包括冷杉、雪松、油杉、北美乔松、金钱松和铁杉。银杉和松属与云杉形成一个分支；雪松是剩余的冷杉属的姐妹群，两个属北美乔松和铁杉形成一个与金钱松姐妹的分支。不同基因树中银杉、雪松和金钱松的不一致位置可以用古老的辐射和/或分子同型进化来解释。对北美乔松的杂种起源假说不支持。基于分子定年，现存的松科属自大约 2.06 亿年前就开始分化，早于泛大陆的分裂，而松型属的分化早于冷杉型属的分化。此外，我们的研究表明，松科属的进化发生了两次辐射事件，一些重要的形态特征基于祖先状态重建发生了多次进化。
