Morphological and Molecular Investigations on the Orthotricheae (Orthotrichaceae: Bryopsida)

附生植物在陆地植物中占有举足轻重的地位，因为它们是唯一一种在生命周期中以单倍体配子体阶段而非二倍体孢子体阶段占主导地位的陆地植物，而且它们的生殖系统依靠水来实现精子到卵子的运动。在这种情况下，它们可以被认为是“植物中的两栖动物”，标志着水生生物和完全陆生生物之间的过渡。苔藓是迄今为止最大的苔藓植物群，大约有12000种。苔藓结构特征的进化，包括染色体数目，尽管苔藓植物对植物多样性的一般理解很重要，但人们对苔藓的进化知之甚少。本项目将研究藓科藓类植物间的相互关系。正三科植物分布在各大洲，是热带和温带生态系统的不同组成部分。本研究将结合DNA水平变异的分子分析、生殖生物学、染色体数目和结构的研究以及整株植物的比较解剖学。这些综合分析的结果将有助于揭示生物学特征之间的关系，如生殖生物学和染色体数目的变化，以及通过近缘和远缘物种之间DNA结构差异估计的分子多样化率。

Shaw DEB 9806955 Byophytes occupy a pivotal position among land plants because they are the only land plants in which the haploid gametophyte stage rather than the diploid sporophyte stage of the life cycle is dominant and because their reproductive system relies on water for movement of sperm to eggs. In that context, they can be thought of as the "amphibia of plants," marking the transition between aquatic and completely terrestrial organisms. The mosses are by far the largest groups of bryophytes, with some 12,000 species. The evolution of moss structural characteristics, including chromosome number, is poorly understood despite the importance of bryophytes for a general understanding of plant diversity. This project will investigate the relationships among species in the large moss family Orthotrichaceae. The Orthotrichaceae are represented on every continent, and are diverse components of both tropical and temperate ecosystems. This research will combine molecular analyses of variation at the DNA level with studies of reproductive biology, chromosome numbers and structure, and comparative anatomy of whole plants. Results of these combined analyses will shed new light on the relationship between biological characteristics such as reproductive biology and changes in chromosome number, and rates of molecular diversification as estimated by differences in DNA structure among closely related and more distantly related species.