Institute of Systematic Botany, University of Zurich, Zurich, Switzerland.
Mol Phylogenet Evol. 2012 Oct;65(1):23-34. doi: 10.1016/j.ympev.2012.05.015. Epub 2012 May 27.
The type section of Primula (Primulaceae), here considered to include seven species, is phylogenetically quite isolated in its genus. Although its species are popular ornamentals, traditional medicinal plants and model organisms for the study of heterostyly, the section has not yet been studied from a phylogenetic or evolutionary perspective. Using phylogenetic analysis of nuclear ITS and plastid data from all species and subspecies, we find that widespread Primula elatior is genetically heterogeneous and non-monophyletic to most if not all of the other ingroup taxa. The Genealogical Sorting Index (GSI) indicates that the assumption of all currently accepted species being independent lineages is consistent with the data. It is possible that P. elatior in its current circumscription may represents the disjointed remnant of an ancestral species from which the other recognized species diverged. However, based on available data, the alternative possibility of introgression explaining the non-monophyly of this species cannot be excluded. Species trees show P. elatior and P. veris as sister species. Primula vulgaris and P. juliae are closely related, while, in contrast to previous assumptions, P. renifolia does not appear to be a close relative of P. megaseifolia. With the section's isolation from the rest of the genus and very short internal branches, our dataset also presents a case study of the confounding effects of different branch length priors on the Bayesian estimation of resulting branch length estimates. Experimental runs using different priors confirm the problem of resulting estimates varying by orders of magnitude, while topology and relative branch lengths seem unaffected.
本文考虑将报春花属（报春花科）的模式标本包括 7 个种，该类型标本在属内系统发育上是相当孤立的。尽管其物种是受欢迎的观赏植物、传统药用植物和研究异型花柱的模式生物，但该类群尚未从系统发育或进化的角度进行研究。利用来自所有种和亚种的核 ITS 和质体数据的系统发育分析，我们发现广泛分布的报春花（P. elatior）在遗传上是异质的，并且在大多数情况下（如果不是全部）与其他内群分类群没有单系关系。系统发生分类指数（GSI）表明，目前所有被接受的种都是独立谱系的假设与数据一致。报春花（P. elatior）可能在其当前的范围内代表了一个祖先物种的不连续残余，而其他被认可的物种则从该祖先物种中分化而来。然而，基于现有数据，不能排除这种物种的非单系性是由基因渗入解释的可能性。物种树显示报春花（P. elatior）和欧洲报春花（P. veris）为姐妹种。报春花（P. vulgaris）和报春花（P. juliae）亲缘关系密切，而与之前的假设相反，报春花（P. renifolia）似乎与大花报春花（P. megaseifolia）没有密切的亲缘关系。由于该类群与属内其他类群的隔离以及内部分支非常短，因此我们的数据集还提供了一个案例研究，说明不同分支长度先验对贝叶斯估计结果分支长度估计的混淆影响。使用不同先验值的实验运行证实了结果估计值因数量级而异的问题，而拓扑结构和相对分支长度似乎不受影响。
