Data from: Polyploidisation and geographic differentiation drive diversification in a European high mountain plant group (Doronicum clusii aggregate, Asteraceae)

Range shifts (especially during the Pleistocene), polyploidisation and hybridization are major factors affecting high-mountain biodiversity. A good system to study their role in the European high mountains is the Doronicum clusii aggregate (Asteraceae), whose four taxa (D. clusii s.s., D. stiriacum, D. glaciale subsp. glaciale and D. glaciale subsp. calcareum) are differentiated geographically, ecologically (basiphilous versus silicicolous) and/or via their ploidy levels (diploid versus tetraploid). Here, we use DNA sequences (three plastid and one nuclear spacer) and AFLP fingerprinting data generated for 58 populations to infer phylogenetic relationships, origin of polyploids—whose ploidy level was confirmed by chromosomally calibrated DNA ploidy level estimates—and phylogeographic history. Taxonomic conclusions were informed, among others, by a Gaussian clustering method for species delimitation using dominant multilocus data. Based on molecular data we identified three lineages: (i) silicicolous diploid D. clusii s.s. in the Alps, (ii) silicicolous tetraploid D. stiriacum in the eastern Alps (outside the range of D. clusii s.s.) and the Carpathians and (iii) the basiphilous diploids D. glaciale subsp. glaciale (eastern Alps) and D. glaciale subsp. calcareum (northeastern Alps); each taxon was identified as distinct by the Gaussian clustering, but the separation of D. glaciale subsp. calcareum and D. glaciale subsp. glaciale was not stable, supporting their taxonomic treatment as subspecies. Carpathian and Alpine populations of D. stiriacum were genetically differentiated suggesting phases of vicariance, probably during the Pleistocene. The origin (autopolyploid versus allopolyploid) of D. stiriacum remained unclear. Doronicum glaciale subsp. calcareum was genetically and morphologically weakly separated from D. glaciale subsp. glaciale but exhibited significantly higher genetic diversity and rarity. This suggests that the more widespread D. glaciale subsp. glaciale originated from D. glaciale subsp. calcareum, which is restricted to a prominent Pleistocene refugium previously identified in other alpine plant species.

分布范围迁移（尤其更新世时期）、多倍化（polyploidisation）与杂交是影响高山生物多样性的核心驱动因素。研究上述因素在欧洲高山生态系统中作用的理想类群为多榔菊复合群（Doronicum clusii aggregate，菊科Asteraceae），该复合群包含4个类群：狭义多榔菊（D. clusii s.s.）、斯蒂里亚多榔菊（D. stiriacum）、冰川多榔菊指名亚种（D. glaciale subsp. glaciale）与石灰生冰川多榔菊（D. glaciale subsp. calcareum），这些类群在地理分布、生态习性（喜基性（basiphilous）与喜硅质（silicicolous））以及倍性水平（二倍体（diploid）与四倍体（tetraploid））上均存在分化。本研究针对58个居群获取了DNA序列（3个质体（plastid）序列与1个核间隔区（nuclear spacer）序列）以及扩增片段长度多态性指纹图谱（AFLP fingerprinting）数据，以此推断该复合群的系统发育关系、多倍体起源（其倍性水平经染色体校准的DNA倍性估算值得以验证）以及谱系生物地理学历史。本研究的分类学结论主要基于采用显性多位点数据进行物种界定的高斯聚类法（Gaussian clustering method）得出。基于分子数据，本研究共识别出3个支系：（1）阿尔卑斯山脉分布的喜硅质二倍体狭义多榔菊；（2）东阿尔卑斯山脉（狭义多榔菊分布区之外）与喀尔巴阡山脉分布的喜硅质四倍体斯蒂里亚多榔菊；（3）东阿尔卑斯山脉分布的喜基性二倍体冰川多榔菊指名亚种，以及东北阿尔卑斯山脉分布的喜基性二倍体石灰生冰川多榔菊。高斯聚类法均将每个类群鉴定为独立类群，但石灰生冰川多榔菊与冰川多榔菊指名亚种的区分结果并不稳定，这支持将二者处理为亚种的分类学处理方式。斯蒂里亚多榔菊的喀尔巴阡居群与阿尔卑斯居群存在遗传分化，提示其可能在更新世时期经历了隔离分化阶段。斯蒂里亚多榔菊的起源（同源多倍体（autopolyploid）与异源多倍体（allopolyploid））仍不明确。石灰生冰川多榔菊在遗传与形态上与冰川多榔菊指名亚种的区分度较低，但其遗传多样性与稀有性均显著更高。这提示分布更广的冰川多榔菊指名亚种起源于石灰生冰川多榔菊，而石灰生冰川多榔菊仅分布于此前在其他高山植物中发现的一处重要更新世避难所（Pleistocene refugium）中。