Division of Molecular Ecology, State Key Laboratory of Grassland Farming System, College of Life Science, Lanzhou University, Lanzhou, Gansu, PR China.
Heredity (Edinb). 2012 May;108(5):552-62. doi: 10.1038/hdy.2011.123. Epub 2011 Dec 21.
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 Pinus densiflora, and also whether two narrowly distributed pines in the same region, Pinus funebris and Pinus 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. P. 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种形成可能比以前意识到的更为普遍，但在针叶树中，同倍体杂种起源的案例很少有很好的记录。我们研究了中国东北地区目前广泛分布的两种松树——蒙古松和赤松，以及同一地区两种分布狭窄的松树——白皮松和华山松，是否可能通过同倍体杂种形成起源于这两个广泛分布的物种。我们的研究结果基于叶绿体（cp）、线粒体（mt）DNA 和核基因序列变异的种群遗传分析，表明这两个广泛分布的物种在 cp 和 mtDNA 变异以及在调查的八个核基因座中的两个的单倍型变异方面存在分歧。我们的分析进一步表明，蒙古松和赤松在发生在中国东北的最严重的第四纪冰川期保持着异域分布，但随后表现出快速的分布范围扩张。发现白皮松和华山松含有区分蒙古松和赤松的叶绿体型和核单倍型混合物，支持它们可能通过蒙古松和赤松之间的二次接触和杂交，然后通过同倍体杂种形成起源的假说。
