Evolution, biodiversity and biogeography of parasitic plants using the genus cuscuta (CONVOLVULaceae) as a model of study

寄生性在显花植物的生殖发育中独立地进化了几次。寄生植物有22科277属4000余种。尽管人们对它们的研究已经有很长的时间，但对它们的进化、生物多样性和植物地理学，特别是物种水平的了解仍然很少。菟丝子属（菟丝子，旋花科）将被用作研究的模型，因为它的经济意义，保护问题，以及它在全球范围内带来的理论问题的复杂性。短期目标是了解北美和南美菟丝子物种的进化和地理分布，以及为这些物种创建生物多样性数据库。本文将对以下进化假说进行检验：（1）杂交和多倍性在菟丝子的进化中起作用。(2)该属的亚属分类并不能反映其系统发育。(3)还有一些未被描述的物种，而一些描述的物种在分类学上并不合理。生物多样性数据库将可在互联网上搜索，应包括以下条目：保护/入侵状况、分类信息、地理分布、宿主范围、生物学和生态学数据以及用于识别的图像。数据库中的地理信息将用于绘制每个种和变种的分布范围，并与进化结论一起，结果将有助于了解该属的历史地理。此外，两个假设有关的植物地理学将进行测试：（1）发芽要求的影响，至少部分，物种的地理分布;（2）自养幼苗的菟丝子可能会形成菌根协会，这反过来又可能影响物种的分布。长期目标是建立寄生植物的综合研究计划。首先，遵循与这里描述的方法类似的方法，我将把对菟丝子的研究扩展到世界范围，其次，我也将考虑寄生植物的新属/科。

Parasitism has evolved independently several times in the phylogeny of flowering plants. There are roughly 4000 species of parasitic plants classified in 277 genera from 22 families. Although they have been studied for a long time, their evolution, biodiversity and biogeography, especially at species level are still poorly understood. The genus Cuscuta (dodders, Convolvulaceae) will be used as a model of study because of its economic significance, conservation problems, and the complexity of theoretical problems it brings up at a global scale. THE SHORT-TERM GOALS are to understand the evolution and biogeography of the North and South American species of dodder, as well as to create a biodiversity database for these species. The following evolutionary hypotheses will be tested: (1) Hybridization and polyploidy have played a role in the evolution of dodders. (2) The infrageneric classification of the genus does not reflect its phylogeny. (3) There are still undescribed species, whereas some of the species described are not sound taxonomically. The biodiversity database will be searchable over the internet and should include entries such as: the conservation/invasive status, taxonomic information, geographic distribution, the host range, biology and ecology data, and images for identification. The geographical information contained in the database will be used to map the distribution ranges for each species and variety and, together with the evolutionary conclusions, the results should give an understanding of the historical biogeography of this genus. In addition, two hypotheses in relation to biogeography will be tested: (1) Germination requirements influence, at least in part, the geographical distribution of species; (2) Autotrophic seedlings of dodders may form mycorrhizal associations, which in turn may influence the distribution of species. THE LONG-TERM OBJECTIVES are to build up an integrative research program on parasitic plants. Firstly, following similar approaches to those described here, I will expand the study of Cuscuta to a worldwide scale, and secondly, I will consider new genera/families of parasitic plants as well.