小檗科的花粉演化

以APG III定义的基部真双子叶分支（Basal Eudicots）中毛茛目（Ranunculales）小檗科（Berberidaceae）为研究对象，选取4个DNA片段（rbcL、matK、trnLF和26S rDNA），利用最大似然法构建分子系统树，结合已报道的花粉形态数据，分析了该科16个属的花粉形态。选择花粉分散单位、极性、形状、大小、萌发孔数目、萌发孔位置、外萌发孔形状、覆盖层上元素、覆盖层纹饰和外壁厚度共10个关键性状，采用简约法推断了该科花粉的祖征、共衍征和演化式样。研究表明：单粒、等极、近球形、中等大小是小檗科花粉的祖征。无极、多萌发孔和周面孔是小檗亚科（Berberidoideae）的共衍征，支持其为一个单系。三萌发孔分别为鬼臼亚科（Podophylloideae）、南天竹亚科（Nandinoideae）各自的共衍征；覆盖层上元素不存在是小檗亚科和南天竹亚科的共衍征，将它们与鬼臼亚科区分开来，同时也支持了小檗亚科和南天竹亚科之间的姐妹关系。此外，对一些属花粉形态的演化意义进行了讨论，提出一些特殊的花粉性状可以用来定义某些属，如Bongardia和兰山草属（Ranzania）。

Evolution of Pollen in the Family Berberidaceae

In the APG III, the family Berberidaceae is placed in the Ranunculales within the basal Eudicots. Here, the phylogenetic relationships within Berberidaceae were reconstructed using the Maximum Likelihood method on sequence data from four genomic regions （nuclear ribosomal 26S rDNA and plastid rbcL, matK, and trnLF）. Based on previously reported phylogenetic tree and pollen observation, the pollen morphologies of 16 genera of this family were investigated. Pollen plesiomorphy,synapomorphy, and evolutionary pattern were revealed by Fitch Parsimony analysis. Ten pollen characters, including dispersal unit, polarity, shape class, size, aperture number, aperture position, ectoaperture shape, supratectal elements, tectum sculpture, and exine thickness, were evaluated to reassess phylogenetic relationships. Tracing pollen character evolution showed that Berberidaceae possessed a series of plesiomorphies, such as the monad pollen unit, isopolarity, spheroidal shape and medium size. Apolarity, multiple apertures and global aperture state were found to be synapomorphies for the Berberidoideae, strongly supporting the monophyly of this subfamily. Triaperture was a synapomorphy for both Podophylloideae and Nandinoideae, respectively. Berberidoideae and Nandinoideae shared the synapomorphy supratectal elements absent, which distinguished them from Podophylloideae, and supported the sister relationship between Berberidoideae and Nandinoideae. Pollen evolutionary significance of some genera was discussed, and several pollen characters were suggested to be used for defining certain genera, such as Bongardia and Ranzania.