Phylogeny and Systematics of Coccoid Prasinophytes

[707262 . FAWLEY]绿藻被称为绿藻门，它包括与所有绿色植物的祖先相似的生物。一些Prasinophyceae是鞭毛虫，但其他是非鞭毛虫（球虫）单细胞。一些不同于陆生植物和其他绿藻的不寻常的色素和细胞特征出现在水生植物中。然而，一些研究表明，Prasinophyceae不是一个自然类，而是可能由几个不同的进化系组成。在特定种类的裸生藻类中共享的细胞结构和色素组成的变化可能表明存在具有单一共同祖先的谱系。在这项研究中，Marvin Fawley将专注于一组特殊的prasinophytes，那些拥有类胡萝卜素prasinoxanthin。几条线索的证据表明，这些生物来自一个单一的进化谱系。然而，目前的分类系统将含有prasinoxanthin的生物分为两个不同的目。该项目将检验含有prasinoxanthin的藻类形成单一谱系的假设。将使用18S核糖体RNA基因序列分析以及色素和生化数据。大多数检查的生物将是球虫，因为这些生物很少得到很好的研究。然而，球藻对我们了解海洋浮游植物的多样性至关重要。更好地了解这些生物的系统发育将大大有助于对这种多样性的持续研究，以及我们对绿色植物进化的理解。

9707262 FAWLEY The class of green algae called the Prasinophyceae includes organisms similar to the ancestors of all green plants. Some Prasinophyceae are flagellates, but others are nonflagellate (coccoid) unicells. Some unusual pigments and cellular features that are distinct from land plants and other green algae occur in prasinophytes. However, several studies have revealed that the Prasinophyceae is not a OnaturalO class, but may instead be composed of several different evolutionary lines. Variations in cell structure and pigment composition that are shared among particular species of prasinophyte algae may indicate the presence of lineages that share a single common ancestor. In thsi research, Marvin Fawley will focus on a particular group of prasinophytes, those that possess the carotenoid prasinoxanthin. Several lines of evidence suggest that these organisms are from a single evolutionary lineage. However, current classification systems place the prasinoxanthin possessing organisms in two separate orders. This project will test the hypothesis that the prasinoxanthin possessing algae form a single lineage. 18S ribosomal RNA gene sequence analysis as well as pigment and biochemical data will be used. Most of the organisms examined will be coccoid prasinophytes, because few of these organisms have been well studied. However, the coccoid prasinophytes are critical to our understanding of the diversity of oceanic phytoplankton. Better knowledge of the phylogeny of these organisms will contribute greatly to ongoing research on this diversity, as well as to our understanding of green plant evolution.