Phylogenetic Relationships in Schiedea and Alsinidendron (Caryophyllaceae) and the Evolution of Dioecy

雌雄异株，即一个物种中雌性（雌蕊）和雄性（雄蕊）植物分离的现象，在世界上大约15%的开花植物中已经进化出来。石竹科石竹属和石竹属为研究夏威夷群岛雌雄异株的进化提供了极好的机会。22个种中的8个在雌雄异株的进化中表现出不同的阶段（这些繁殖系统统称为双系）。在遥远的海洋岛屿上明显的高频率的双染色体已被用来支持几个关于雌雄异株进化的对比假设。如果不知道dicliny是否在岛上就地进化，以及它是否在岛上进化了多次，单靠分布数据很难决定这个问题。Drs。加州大学欧文分校的韦勒和酒井将利用形态学、染色体和分子数据研究这两个属的进化关系。利用DNA分析来重建系统发育关系将提供一个独立的评估，而不受可能与育种系统相关的花形态趋同进化的影响。对雪梨属和Alsinidendron的系统发育将增加对这些不同属中与适应性辐射相关的基本进化力的理解，并有助于解释在该群体中发现的新特征，包括专门的花蜜腺、藤蔓和肉质果实结构。由于这些育种系统在作物物种中具有潜在的重要性，因此关于双盲进化的信息也引起了普遍的兴趣。夏威夷的许多种类的雪梨属和Alsinidendron被认为已经灭绝，本研究获得的信息将有助于解释植物的繁殖系统、稀有性和灭绝可能性之间的关系。

Dioecy, the occurrence of separate female (pistillate) and male (staminate) plants in a species, has evolved in about 15% of the world's flowering plants. Schiedea and Alsinidendron of the carnation family (Caryophyllaceae) provide an excellent opportunity to study the evolution of dioecy on the Hawaiian Islands. Eight of the 22 species of Schiedea show varying stages in the evolution of dioecy (collectively these breeding systems are termed diclinous). The apparently high frequency of dicliny on remote oceanic islands has been used to support several contrasting hypotheses about the evolution of dioecy. Distributional data alone are difficult to decide the matter, without knowing whether dicliny has evolved in situ on the islands and whether it has evolved multiple times there. Drs. Weller and Sakai of the University of California at Irvine will study evolutionary relationships in these two genera using morphological, chromosomal, and molecular data. The use of DNA analyses to reconstruct phylogenetic relationships will provide an independent assessment uncomplicated by convergent evolution of floral morphology that may be associated with breeding systems. A phylogeny of Schiedea and Alsinidendron will increase understanding of the basic evolutionary forces associated with adaptive radiation in these diverse genera and help in interpreting novel features found in the group, including specialized floral nectaries, vines, and fleshy fruiting structures. Information on the evolution of dicliny is also of general interest because of the potential importance of these breeding systems in crop species. A number of species of Schiedea and Alsinidendron are believed extinct in Hawaii, and the information obtained in this research will be useful for interpreting relationships among breeding systems, rarity, and the likelihood of extinction in plants.