Departamento de Botánica y Fisiología Vegetal, University of Salamanca, E-37007 Salamanca, Spain; Biobanco de ADN Vegetal, University of Salamanca, Edificio Multiusos I+D+i, Calle Espejo s/n, 37007 Salamanca, Spain.
Departamento de Botánica y Fisiología Vegetal, University of Salamanca, E-37007 Salamanca, Spain; Biobanco de ADN Vegetal, University of Salamanca, Edificio Multiusos I+D+i, Calle Espejo s/n, 37007 Salamanca, Spain.
Mol Phylogenet Evol. 2021 Feb;155:107006. doi: 10.1016/j.ympev.2020.107006. Epub 2020 Nov 5.
The Balkan Peninsula is recognized as one of the hotspots of biodiversity in Europe. This area has shown since the Last Glacial Maximum appropriate conditions for species diversification and hybridization, which has led to the existence of numerous taxonomically unresolved entities. Here, we focus on the Western Balkans and explore the genetic structure and relationships among species belonging to the V. austriaca - V. orbiculata diploid-polyploid complex, including populations showing intermediate morphologies. A combination of nuclear markers (microsatellites), plastid DNA regions (trnH-psbA, ycf6-psbM) and ploidy level estimations using flow cytometry are employed to assess the genetic structure and evolutionary dynamics of this polyploid complex. To reconstruct the evolutionary history, an approximate Bayesian computation approach is combined with projections of the species distribution models onto the climatic scenarios of the Mid-Holocene (6 ka BP) and Last Glacial Maximum (22 ka BP). Four main groups were found: one well-established entity within the diploid level, V. dalmatica, a second diploid-tetraploid group which corresponds to V. orbiculata, a hexaploid cluster harboring V. austriaca subsp. jacquinii individuals, and an enigmatic tetraploid group. According to the molecular data obtained, this latter cluster represents an allopolyploid cryptic lineage −with V. orbiculata and V. dalmatica as putative parents− morphologically similar to V. orbiculata, but genetically more related to V. austriaca subsp. jacquinii. Veronica dalmatica and this “uncertain tetraploid” group are involved in the formation of the hexaploid taxon V. austriaca subsp. jacquinii, with the possibility of recent gene flow among different cytotypes. The present study supports a scenario of diversification from a diploid common ancestor leading to two different but interrelated lineages. The first one would correspond with the diploid V. orbiculata plus tetraploid individuals of this species arising through allo- and autopolyploidization, and the second one would involve all ploidy levels with allopolyploidization being prevalent.
巴尔干半岛被公认为欧洲生物多样性的热点地区之一。该地区自末次冰期最大值以来，一直为物种多样化和杂交提供了适宜的条件，这导致了无数分类学上未解决的实体的存在。在这里，我们专注于西巴尔干地区，探索属于 V. austriaca-V. orbiculata 二倍体-多倍体复合体的物种的遗传结构和关系，包括表现出中间形态的种群。我们结合使用了核标记（微卫星）、质体 DNA 区域（trnH-psbA、ycf6-psbM）和利用流式细胞术估计的倍性水平来评估这个多倍体复合体的遗传结构和进化动态。为了重建进化历史，我们结合了近似贝叶斯计算方法和物种分布模型对中全新世（6 ka BP）和末次冰期最大值（22 ka BP）气候情景的投影。我们发现了四个主要群体：一个在二倍体水平上确立的实体，V. dalmatica，一个对应于 V. orbiculata 的二倍体-四倍体群体，一个包含 V. austriaca subsp. jacquinii 个体的六倍体聚类，以及一个神秘的四倍体群体。根据获得的分子数据，这个后者聚类代表一个异源多倍体隐系——与 V. orbiculata 和 V. dalmatica 作为可能的亲本——形态上与 V. orbiculata 相似，但在遗传上与 V. austriaca subsp. jacquinii 更为相关。 Veronica dalmatica 和这个“不确定的四倍体”群体参与了六倍体 taxon V. austriaca subsp. jacquinii 的形成，不同细胞型之间可能存在近期的基因流动。本研究支持了一个从二倍体共同祖先多样化的情景，导致了两个不同但相互关联的谱系。第一个谱系与二倍体 V. orbiculata 加上通过异源和自源多倍化产生的该物种的四倍体个体相对应，第二个谱系则涉及所有倍性水平，异源多倍化更为普遍。
