de Mestier Astrid, Lücking Robert, Gutierrez Jorge, Brokamp Grischa, Celis Marcela, Borsch Thomas
Botanischer Garten Freie Universität Berlin Berlin Germany.
Institut für Biologie - Systematische Botanik und Pflanzengeographie Freie Universität Berlin Berlin Germany.
Ecol Evol. 2023 Jan 17;13(1):e9736. doi: 10.1002/ece3.9736. eCollection 2023 Jan.
Using the genus , we assessed the status of nested singletons: individual specimens corresponding to accepted species but in molecular trees appearing nested within clades of closely related species. Normally, such cases would be left undecided, while on the other hand, timely taxonomic decisions are required. We argue that morphological, chorological, and ecological data can be informative to illuminate patterns of speciation. Their use can provide a first step in testing taxon concepts at species level. We focused on five cases of nested singletons in trees of the genus . We employed PCA and cluster analysis to assess phenotypic differentiation. Using geocoordinates, we calculated niche space differentiation based on 19 bioclim variables, by means of PCA and niche equivalency and similarity tests and generated dot maps. We found that the singletons were morphologically distinctive in two of the five cases ( and ), relatively distinctive in two other cases ( and ), and partially overlapping in the last case (). For two cases ( and ), ecological niche space was broadly overlapping, in two cases it was found broadly nested ( and ), and in one case narrowly nested (), but in no case niche differentiation was observed. Niche overlap, similarity and equivalency showed corresponding patterns. Given these data, one would interpret and as presumably well-distinguished taxa, their narrow distribution ranges suggesting recently emerging lineages. The other three cases are not clearcut. Morphological data would suggest particularly conspecific with , but differences in the distribution are intriguing. Our approach would reject the notion of potential synonymy based on nested phylogenetic placement for at least two of the five cases. The other case also shows no complete lack of differentiation which would support synonymy.
利用该属，我们评估了嵌套单型的状况：对应于已接受物种的单个标本，但在分子树中出现在亲缘关系密切的物种分支内。通常情况下，此类情况会悬而未决，而另一方面，又需要及时做出分类学决定。我们认为形态学、分布学和生态学数据有助于阐明物种形成模式。它们的使用可为在物种水平上检验分类单元概念提供第一步。我们聚焦于该属树木中的五个嵌套单型案例。我们采用主成分分析（PCA）和聚类分析来评估表型分化。利用地理坐标，我们基于19个生物气候变量，通过主成分分析以及生态位等效性和相似性检验计算生态位空间分化，并生成点状图。我们发现，在五个案例中的两个案例（和）中，单型在形态上具有明显差异，在另外两个案例（和）中相对有差异，而在最后一个案例（）中部分重叠。对于两个案例（和），生态位空间广泛重叠，在两个案例中发现广泛嵌套（和），在一个案例中狭窄嵌套（），但在任何案例中均未观察到生态位分化。生态位重叠、相似性和等效性呈现出相应模式。鉴于这些数据，人们可能会将和解释为大概是界限分明的分类单元，它们狭窄的分布范围表明是最近出现的谱系。另外三个案例并不明确。形态学数据表明特别是与同种，但分布上的差异很有趣。我们的方法将基于系统发育嵌套位置拒绝至少五个案例中的两个案例存在潜在同义关系的观点。另一个案例也未显示出完全缺乏支持同义关系的分化。
