Chloroplast DNA Phylogeny for the Cyatheaceae

热带树蕨是今天唯一存活的树木， 保留了原始的繁殖类型（通过孢子而不是 比种子）最早的陆地植物的特征。 树 桫椤属复合种的蕨类与其他蕨类不同 由于它们缺乏多倍性（多套染色体）， 产生可育的二倍体杂种。戴安娜·斯坦博士和 大卫·科南特将构建一个进化论或进化计划， 树蕨的关系，作为一个框架， 分析这一群体的物种形成机制， 迄今为止命名的物种和属的相互冲突的分类。 其他科学家试图为 研究小组使用了形态学特征（如叶鳞 性状）服从趋同或平行进化。 Drs. Stein和Conant将研究基因突变的变异， 的叶绿体DNA的差异，以确定 分类群之间变化的模式和方向。 叶绿体 突变差异提供了更直接的反映， 物种之间的遗传差异，并为 追踪这些植物的进化过程

Tropical tree-ferns are the only trees alive today that have retained the primitive type of reproduction (by spores rather than by seeds) characteristic of the earliest land plants. Tree ferns of the Cyathea complex of species differ from other ferns in their lack of polyploidy (multiple sets of chromosomes) and by the production of fertile, diploid hybrids. Drs. Diana Stein and David Conant will construct a phylogeny or scheme of evolutionary relationship for the tree-ferns to serve as a framework for analyzing speciation mechanisms in this group and to resolve conflicting taxonomies of the species and genera named thus far. Attempts by other scientists to construct phylogenies for the group have used morphological features (such as leaf scale characters) subject to convergent or parallel evolution. Drs. Stein and Conant will examine variation in mutational differences in the chloroplast DNA of tree-ferns, to determine the pattern and direction of change among taxa. Chloroplast mutational differences provide a more direct reflection of genetic divergence among species, and hold great promise for tracking the course of evolutionary change in these plants.