Polyploidization is generally considered a major evolutionary force that can alter the genetic diversity, morphology, physiology and ecology of plants. One striking example is the polyploid Urtica dioica complex, in which diploid taxa are often found in remote and partly relictual geographical ranges, in contrast to tetraploid individuals, which have an unknown evolutionary history and occur in a variety of synanthropic habitats. We used a set of 279 plants, evenly representing the geographical and morphological variation of U. dioica s.l. in Europe and Southwest Asia, and employed multivariate and geometric morphometrics and Hyb-Seq sequencing to estimate the extent of differentiation of diploid taxa and the ubiquitous tetraploid cytotype. Diploid subspecies form more-or-less separate clusters in morphological analyses, but our molecular evaluation did not reveal any structure. Moreover, tetraploids coalesced with diploids in both morphological and molecular analyses. This disparity between morphological and molecular data might be driven by (1) local adaptation of the diploid cytotype that is mirrored in specific phenotypes, (2) only recent genetic diversification of the group and (3) homoploid and heteroploid hybridization events.

中文翻译：

---

荨麻（Urticaceae）的形态和遗传差异

多倍体化通常被认为是主要的进化力，可以改变植物的遗传多样性，形态，生理和生态。一个引人注目的例子是多倍体荨麻疹复合体，其中四倍体类群通常在偏远和部分遗迹的地理范围内发现，而四倍体个体则具有未知的进化历史并出现在多种合人类生境中。我们使用了279种植物，均匀地代表了U. dioica sl的地理和形态变化在欧洲和西南亚，并采用多元和几何形态计量学和Hyb-Seq测序方法来估算二倍体分类群的分化程度和普遍存在的四倍体细胞型。二倍体亚种在形态学分析中或多或少地形成了单独的簇，但是我们的分子评估没有揭示任何结构。此外，在形态学和分子分析中，四倍体与二倍体结合。形态和分子数据之间的这种差异可能是由（1）在特定表型中反映的二倍体细胞型的局部适应性，（2）仅该组的最近遗传多样性和（3）同倍体和异倍体杂交事件引起的。