METHODS: Phylogeny and biogeography of the subsect. Ledum of the genus Rhododendron were assessed using phylogenetic trees constructed based on the analysis of variation in chloroplast petB-petD, trnV-ndhC, trnH-psbA, K2R-K707, atpB oligo2 - rbcL oligo5 and nuclear (ITS1) markers of four Eurasian and one American species (65 populations, 408 individuals). The data were evaluated with Maximum Parsimony and Bayesian analysis. Molecular dating and ancestral areas reconstruction were obtained.
RESULTS: Dense sampling revealed widespread presence of shared haplotypes and ribotypes among Ledum populations and species. Two American, three Eurasian and one mixed lineage diversified during the Neogene climate cooling and then rapidly dispersed during the Pleistocene. The ability to accumulate high genetic diversity and to preserve it across distribution ranges and generations prevented Ledum from lineage sorting. As a result, a species complex with a reserve of genetic variability appeared.
CONCLUSIONS: Although no clear phylogenetic inference can be obtained at present, the plastid genealogy is consisted with the nuclear genealogy and demonstrates the processes involved in speciation in the Ledum species complex.
方法:亚科的系统发育和生物地理学。使用基于叶绿体petB-petD变异分析构建的系统发育树评估了杜鹃花属的叶,trnV-ndhC,trnH-psbA,K2R-K707,atpBolig2-rbcLolig5和四个欧亚物种和一个美洲物种的核(ITS1)标记(65个种群,408个人)。使用最大简约和贝叶斯分析对数据进行评估。获得了分子定年和祖先区域重建。
结果:密集采样揭示了Ledum种群和物种之间广泛存在共有的单倍型和核糖型。两个美国人,在新近纪气候变冷期间,三个欧亚和一个混合谱系多样化,然后在更新世期间迅速分散。积累高遗传多样性并在分布范围和世代之间保持遗传多样性的能力阻止了Ledum进行谱系分类。因此,出现了具有遗传变异性的物种复合体。
结论:尽管目前还没有明确的系统发育推断,质体谱系与核谱系组成,并证明了Ledum物种复合体中物种形成的过程。