杯萼海桑和格氏海桑自然杂交的分子证据

Interspecific hybridization has been frequently observed in the mangrove genus Sonneratia. However, no natural hybridization has been reported between Sonneratia alba and S. griffithii to date, despite their overlapping distribution in the coast of Andaman Sea. In this study, cysteine proteinase inhibitor gene (cpi) from the nuclear genome, and two intergenic spacers (trnL-trnF and trnV-trnM) from the chloroplast genome, were sequenced to determine whether natural hybridization took place between the two species. Our results revealed two distinct types of cpi sequences from the putative hybrid matching those acquired from S. griffithii and S. alba, respectively. Sequencing of the chloroplast trnL-trnF and trnV-trnM regions showed that S. alba differed from S. griffithii by one nucleotide in each region, and the putative hybrid had the identical sequences with S. griffithii. Molecular data demonstrated clearly that there indeed existed natural hybridization between S. alba and S. griffithii, and that S. griffithii was the maternal parent in this hybridization event.     

柃属植物叶宏观结构及其分类学意义

为了探讨柃属植物属下等级的系统演化路线及一些种的具体分类学地位,采用脉络法对国产柃属植物34种1变种进行了叶宏观结构比较研究,结果显示柃属植物脉序类型皆为环节曲行羽状脉,一级脉表现为较高的一致性,二级脉与一级脉的夹角为锐角或近直角,二级间脉为简单型或复合型,三级脉多为结网型,叶缘末级脉序结环或不完全,网眼的形状和大小不规则,发育不完全或不完善;这些特征存在种间差异,可用于类群的比较和鉴别。研究同时采用UPGMA法对所选16个叶宏观结构性状进行聚类分析,根据系统树的5个分支,讨论了柃属植物叶的基本演化路线。研究证明叶宏观结构特征对本属植物分类及系统演化关系具有重要意义。     

珠海淇澳岛红树林和芦苇湿地底栖硅藻群落比较

研究了珠海淇澳岛红树林湿地和芦苇湿地2007年3月至2008年1月间底栖硅藻群落的结构及其动态特征.结果表明,两种湿地共有底栖硅藻28属113种(变种),其中红树林中检出23属95种(变种),明显高于芦苇湿地的21属42种(变种).底栖硅藻的丰度为14.3～553.5 celk cm-3,不同样地和采样期的多样性指数和均匀度指数不同,但红树林湿地高于芦苇湿地.两种湿地底栖硅藻群落的属种结构存在显著差异,红树林湿地中多以羽纹藻类,如布纹藻属(Gyrosigma)、斜纹藻属(Pleurosigma)和羽纹藻属(Pinnularia)等占优势,而芦苇湿地主要以中心藻类,如圆筛藻属(Coscinodiscus)和小环藻属(Cyclotella)等占优势.相似性分析显示,样地基质对底栖硅藻群落的影响大于季节变化的影响.