Phylogenetic Relationships of Dennstaedtioid Ferns Based on DNA Sequence Analysis

小行星9307091 确定生物之间的进化关系是系统论者的一个主要目标;系统发生学为研究进化过程、地理扩散和迁移以及与共生体和其他生态伙伴的共同进化提供了必要的历史框架。 近年来，DNA测序技术为植物，特别是显花植物的系统发育分析提供了新的数据。 从历史上看，蕨类植物一直是主要的分类学混淆的主题，特别是在较高的分类等级（科和目），并且对于这组ca存在各种各样的分类和假设的分类。一万个物种。 这种混淆部分是由于缺乏形态特征，这些形态特征在其表达或物种之间都是可变的，但足够一致以同源，即在许多不同的物种和属中相似和可比较。 DNA序列数据是理想的特征，因为这两个原因：在分类群之间可变，但在所有分类群之间都是可比的，至少对于功能重要的基因来说是如此。 犹他州州立大学的保罗·沃尔夫（Paul Wolf）博士正在对许多与“dennstaedtioid”类有亲缘关系的蕨类植物的叶绿体光合作用基因进行DNA测序，以便在突变差异随时间推移跟踪物种分化的工作假设下重建它们的进化史。%%% 一个独立的分子数据集将提供一个有价值的工具，用于评估各种蕨类植物群的起源，以及检查形态和染色体变异的模式。 的dennstaedtioid蕨类植物构成的leptosporangiate或“更高”的蕨类植物的主要组成部分，从这项研究的数据最终将结合从其他实验室的DNA测序工作的结果在蕨类植物提供一个系统发育框架的所有主要蕨类植物谱系。

9307091 Wolf Determining evolutionary relationships among organisms is a major goal of systematists; phylogenies provide the necessary historical framework for studies of evolutionary processes, biogeographic dispersal and migration, and coevolution with symbionts and other ecological associates. Recently, DNA sequencing has provided valuable new data for phylogenetic analysis of plants, especially the flowering plants. Historically, ferns have been the subject of major taxonomic confusion, particularly at upper taxonomic ranks (families and orders), and a wide variety of classifications and hypothetical phylogenies exists for this group of ca. 10,000 species. This confusion results in part from a lack of morphological features that are both variable in their expression or form species to species but coherent enough to be homologous, that is, similar and comparable across numerous different species and genera. DNA sequence data are ideal characters for both reasons: variable among taxa but comparable across all of them, at least for functionally important genes. Dr. Paul Wolf of Utah State University is sequencing DNA from the chloroplast photosynthetic gene for numerous fern species allied in the "dennstaedtioid" group, in order to reconstruct their phylogeny under the working assumption that mutational differences track the divergence of species through time. %%% An independent molecular set of data will provide a valuable tool for assessing the origins of various fern groups as well as for examining patterns of morphological and chromosomal variation. The dennstaedtioid ferns constitute a major component of the leptosporangiate or "higher" ferns, and the data from this study will ultimately be combined with results from other laboratories working on DNA sequencing in ferns to provide a phylogenetic framework for all major fern lineages.