Dissertation Research: Phylogenetic Relationships within Passiflora L. Section Cieca Mast. (Passifloraceae)

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Passiflora (plant family Passifloraceae) is a large genus consisting of approximately 500 species primarily occurring in tropical America, Southeast Asia, and Australia. Passion flowers are popular garden plants because of their beautiful, intricate flowers and are grown commercially for their fruit. Additionally, they are being investigated for their medicinal applications. Passiflora section Cieca currently comprises 13 species of herbaceous to woody vines that are characterized by small flowers without petals, filaments of the corona in two series and reticulate seed coats. The section is distributed in the southern United States, Mexico, Central America, South America and the Caribbean. The flowers are primarily pollinated by bees and wasps, with an interesting shift to hummingbird pollination in three species occurring in Jamaica and southern Mexico. One species within section Cieca, Passiflora clypeophylla, is suspected to be extinct but this has not been definitively proven. Three others are listed as endangered or threatened. In order to examine the evolutionary relationships within section Cieca, we will conduct a detailed revision of the group focusing on the combined analysis of DNA sequences and morphological characters. Close attention will be paid to pollination biology in order to examine the selective forces that have led to a change from bee and wasp to hummingbird pollination. Where possible the butterfly herbivores of the species within section Cieca will be observed and identified in order to supplement literature reports and to investigate the close relationship between passion-vine butterflies (Heliconiinae) and Passiflora. A detailed key, descriptions, distribution maps, and illustrations will be included in the revision, along with cladistic, biogeographical and ecological analyses. The proposed study will significantly contribute to a better understanding of evolution at the species level in the Passifloraceae. This investigation will be the first to incorporate modern cladistic methods in a morphological study of any group within the genus Passiflora. The proposed research will also use combined morphological and molecular data matrices to develop hypotheses of phylogenetic relationships in the section and will contribute to a better understanding of the utility of such an approach in plant systematics. In addition, this research will permit the evaluation of the Heliconiinae-Passiflora coevolutionary relationship based upon a well-supported phylogenetic hypothesis for a group of species within Passiflora. Lastly, this study will be one of the few studies to attempt to determine the evolutionary forces that have led from hymenopteran to bird pollination in a group of closely related, tropical species. Thus, the result of the proposed study will be a more extensive understanding of evolutionary trends and relationships within a group of rapidly evolving plant species of the neotropics.