狭义五福花科的分子系统学和物种分化

Molecular Phylogeny and Species Speciation of Adoxaceae.s.s

狭义五福花科(Adoxaceae.s.s)仅含3属4种,但该科的物种分化、系统发育和分类一直存在争议。本文通过测定东方五福花和血满草的ITS(核糖体DNA内转录间隔区)序列,构建了包括狭义五福花科(4种)、广义忍冬科接骨木属、荚属以及其余4属植物在内的系统发育树。研究结果不支持狭义五福花科内根据形态学证据做出的系统发育假设四福花不是该科中最早分化出来的种;该物种与五福花属的两个物种形成一个单系群,与另一分支华福花属相对应。该科中3个物种,四福花、五福花和华福花之间的分化主要是在二倍体水平上的异域分化,而东方五福花则是通过多倍化形成的。粗略的时间估算表明这些物种之间的分化较晚,可能在第三纪末至第四纪早中期,与青池高原近期强烈隆升以及冰期气候反复变化形成的环境变迁密切相关。

It remains unclear about the speciation and phylogeny of Adoxaceae s.s., a small family with 3 genera and 4 species. In this paper, ITS （ nuclear DNA internal transcribed spacer） regions of Adoxa orientalis and Sambucus adnata were firstly sequenced. Phylogenetic trees were constructed for all species of Adoxaceae （four species）, Sambucus, Viburnum and four genera of Caprifoliaceae. The divergences among fottr species of this family were further calculated based on the calibration of the fossil records of the Caprifoliaceae and the general evolutionary rate of herbs for ITS. The phylogenetic analyses did not support the previous assumptions on the phylogeny and species divergence of Adoxaceae s.s. based on the morphological evidence： Tetradoxa is not the firstly diverged and it clustered with two species of Adoxa as a monophylogenetic group, paralleling to the other lineage comprising of monotypic Sinadoxa. The allopatric speciation at the diploid level might have contributed to the differentiation among Sinadoxa corydalifolia, Tetradoxa omeiensis and Adoxa moschatellina and the polyploidy to the origin of A. orientalis. The crude timing based on ITS sequence differentiation suggested a recent divergence among all four species probably between the late Miocene and the Tertiary and this speciation process might be closely correlated with habitat fragmentation and change due to the extensive uplifts of the Qinghai-Tibetan Plateau and climatic oscillation during the glacial and interglacial ages occurred at this stage.