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

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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.