Species delimitation in the genus Greenwayodendron based on morphological and genetic markers reveals new species
Species delimitation in the genus Greenwayodendron based on morphological and genetic markers reveals new species
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DOI：
10.1002/tax.12064
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发表时间：
2019-06-01
期刊：
影响因子：
3.4
通讯作者：
Hardy, Olivier J.
中科院分区：
文献类型：
--
作者：
Lissambou, Brandet-J.;Couvreur, Thomas L. P.;Hardy, Olivier J.
结合遗传和形态标记是一种强有力的物种划分方法，热带物种复合体中非常需要这种方法。绿树属(番荔枝科)是广泛分布于西非至东非热带雨林的一种乔木属。目前已发现两个种和四个亚种分类群。然而，初步的遗传研究和形态观察表明，出现了更多的物种，到目前为止还没有描述。通过结合形态和种群遗传学数据，我们测试了绿树内的物种划分。首先，对大约1000个标本的肉眼观察表明，存在7个形态群：其中4个出现在中非，重叠在加蓬，另外3个是异地分布的，分别出现在西非、东非和圣多美和普林西比群岛。通过对233个标本编码的27个形态性状的分析，证实了它们的形态分化。其次，在8个核微卫星上对800个样本进行基因分型后，贝叶斯聚类分析(结构)发现了与采样充分的形态群相对应的4个遗传簇，但未能分离出剩余的3个由少量样本代表的形态群。然而，我们表明这是结构算法的固有限制，而因子对应分析(FCA)和成对F-ST和R-ST度量证实了所有形态群的遗传分化。我们认为，同域种群之间发生的明显的遗传分化主张遵循生物物种的概念来识别不同的物种。我们的分析表明，目前对绿树的分类处理低估了物种的总数。我们鉴定了两个新种，并支持在两个变种(G.suaveolens subsp.)的种级上进行分离。Suaveolens var.Gabonica、猪毛球藻(G.suaveolens subsp.)Suaveolens var.Suaveolens)和一个亚种(G.suaveolens subsp.乌桑巴里)。在圣多美和普林西比收集的标本的分类状况仍然不确定，部分原因是可用可育材料有限。我们的研究强调了结合形态和种群遗传学数据发现新分类群的力量。提供了在物种划界中使用遗传聚类法的指导方针。
Combining genetic and morphological markers is a powerful approach for species delimitation, much needed in tropical species complexes. Greenwayodendron (Annonaceae) is a widespread genus of trees distributed from West to East African rainforests. Two species and four infra-specific taxa are currently recognized. However, preliminary genetic studies and morphological observations suggested the occurrence of additional species, undescribed to date. We tested species delimitation within Greenwayodendron by combining morphological and population genetics data. First, a visual inspection of about a thousand specimens suggested the existence of seven morphogroups: four of them occur in Central Africa and overlap in Gabon while three others are allopatric, occurring respectively in West Africa, East Africa, and the islands of Sao Tome and Principe. Their morphological differentiation was confirmed by analysis of 27 morphological characters coded from 233 herbarium specimens. Second, after genotyping 800 samples at eight nuclear microsatellites, Bayesian clustering analyses (STRUCTURE) identified four genetic clusters corresponding to the well-sampled morphogroups but failed to separate the three remaining morphogroups represented by few samples. However, we show that this is an inherent limit of the STRUCTURE algorithm, whereas factorial correspondence analysis (FCA) and pairwise F-ST and R-ST measures confirmed the genetic differentiation of all morphogroups. We considered that a clear genetic differentiation occurring between sympatric populations advocates for recognizing distinct species following the biological species concept. Our analyses highlight that the current taxonomic treatment of Greenwayodendron underestimates the total number of species. We identified two new species and support separation at the rank of species of two varieties (G. suaveolens subsp. suaveolens var. gabonica, G. suaveolens subsp. suaveolens var. suaveolens) and one subspecies (G. suaveolens subsp. usambaricum). The taxonomic status of specimens collected in Sao Tome and Principe remains inconclusive, partly due to the limited fertile material available. Our study highlights the strength of combining morphological and population genetics data for discovering new taxa. Guidelines for using genetic clustering approaches in species delimitation are provided.