Data from: Genetic divergence, range expansion and possible homoploid hybrid speciation among pine species in northeast China

Although homoploid hybrid speciation in plants is probably more common than previously realized, there are few well-documented cases of homoploid hybrid origin in conifers. We examined genetic divergence between two currently widespread pines in northeast China, Pinus sylvestris var. mongolica and P. densiflora, and also whether two narrowly distributed pines in the same region, P. funebris and P. takahasii, might have originated from the two widespread species by homoploid hybrid speciation. Our results, based on population genetic analysis of chloroplast (cp), mitochondrial (mt) DNA, and nuclear gene sequence variation, showed that the two widespread species were divergent for both cp- and mtDNA variation, and also for haplotype variation at two of eight nuclear gene loci surveyed. Our analysis further indicated that P. sylvestris var. mongolica and P. densiflora remained allopatric during the most severe Quaternary glacial period that occurred in northeast China, but subsequently exhibited rapid range expansions. Pinus funebris and P. takahasii, were found to contain a mixture of chlorotypes and nuclear haplotypes that distinguish P. sylvestris var. mongolica and P. densiflora, in support of the hypothesis that they possibly originated via homoploid hybrid speciation following secondary contact and hybridization between P. sylvestris var. mongolica and P. densiflora.

尽管植物中的同倍体杂交物种形成（homoploid hybrid speciation）可能比此前认知的更为普遍，但针叶树（conifers）中被充分证实的同倍体杂交起源案例仍为数不多。本研究针对中国东北部两种当前广泛分布的松树——樟子松（Pinus sylvestris var. mongolica）与赤松（P. densiflora）开展了遗传分化分析，并探讨了该区域另外两种狭域分布的松树——兴凯松（P. funebris）与高砂松（P. takahasii）是否由这两种广布物种通过同倍体杂交物种形成起源。本研究基于叶绿体（cp）、线粒体（mt）DNA及核基因序列变异的群体遗传学分析，结果显示两种广布物种在cpDNA与mtDNA变异上均存在分化，且在所检测的8个核基因位点中的2个位点上存在单倍型差异。进一步分析表明，在中国大陆东北第四纪最严酷的冰期时段，樟子松与赤松曾保持异域分布，但随后均经历了快速的分布范围扩张。研究发现，兴凯松与高砂松的叶绿体类型及核单倍型均兼具樟子松与赤松的特征，这支持了二者可能是樟子松与赤松二次接触并杂交后，通过同倍体杂交物种形成起源的假说。