Data from: Strong nuclear differentiation contrasts with widespread sharing of plastid DNA haplotypes across taxa in European purple saxifrages (Saxifraga sect. Porphyrion subsect. Oppositifoliae)

The purple saxifrages, Saxifraga sect. Porphyrion subsect. Oppositifoliae, comprise the closest relatives of the arctic-alpine model plant S. oppositifolia and have a centre of diversity in the central and southern European mountain ranges. A multitude of taxa has been described and taxonomic concepts vary among different treatments. Using amplified fragment length polymorphism (AFLP) fingerprinting we show that some taxa indeed form strongly supported genetic entities best recognized on the species level (S. biflora, S. blepharophylla, S. retusa, S. rudolphiana, S. speciosa), while others (S. murithiana, S. paradoxa) are not genetically divergent at all. Saxifraga oppositifolia s. s. is phylogenetically incoherent. Plastid DNA sequence data show very limited congruence with the predominantly nuclear-derived AFLPs. Several co-distributed taxa (S. biflora, S. blepharophylla, S. oppositifolia s. s., S. retusa) share the same set of haplotypes. In the widespread species S. oppositifolia and S. retusa, highly divergent haplotype lineages were discovered, which exhibit a geographic rather than taxonomic structure. Recent and ancient hybridization and/or lineage sorting are likely responsible for the strong incongruence between data derived from nuclear and plastid genomes. Hybridization, which is known to occur among almost all taxa of this group when growing in sympatry, seems, however, insufficient to break down species barriers.

紫虎耳草类群（虎耳草属[Saxifraga]紫虎耳组[sect. Porphyrion]对叶亚组[subsect. Oppositifoliae]）是北极-高山模式植物对叶虎耳草（Saxifraga oppositifolia）的近缘姊妹类群，其多样性中心坐落于中欧与南欧的山地范围。该类群已被发表诸多分类单元，且不同分类学处理所采用的分类概念存在分歧。本研究借助扩增片段长度多态性（amplified fragment length polymorphism, AFLP）指纹图谱分析，证实部分分类单元确实形成了支持度极高的遗传类群，适宜界定为独立物种，包括二花虎耳草（S. biflora）、睫毛虎耳草（S. blepharophylla）、凹叶虎耳草（S. retusa）、鲁道夫虎耳草（S. rudolphiana）以及美丽虎耳草（S. speciosa）；而穆里特虎耳草（S. murithiana）与奇异虎耳草（S. paradoxa）则未表现出任何遗传分化。对叶虎耳草狭义群（S. oppositifolia s. s.）在系统发育上并不连贯。质体DNA序列数据与主要基于核源AFLP标记得到的结果一致性极低。多个同分布类群，即二花虎耳草、睫毛虎耳草、对叶虎耳草狭义群及凹叶虎耳草，共享同一套单倍型（haplotype）。在广布物种对叶虎耳草与凹叶虎耳草中，研究发现了高度分化的单倍型谱系，此类谱系呈现地理分布结构而非分类学结构。近期与古老的杂交事件及/或谱系分选（lineage sorting），极有可能是造成核基因组与质体基因组数据间强烈不一致的原因。尽管已知该类群几乎所有类群在同域分布时均可发生杂交，但这类杂交似乎不足以打破物种间的屏障。