Dissertation Research: Phylogenetic Relationships in the Cistaceae (Rockroses)

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9972646Manos and Arrington Rockroses are ecologically important components of Northern Hemisphere Mediterranean-type shrublands. The Iberian peninsula followed by the U.S. Atlantic Coastal Plain is particularly species-rich. Even though a diverse assortment of vegetative and floral features are present in the family, the Cistaceae are usually known for their aromatic, showy-flowered species which dominate Old World maquis (Corsican for rockrose) ecosystems. This is largely due to theireconomic value to perfumery and horticulture, and their association with a spectacular parasitic flowering plant, Cytinus (family Rafflesiaceae), a root parasite whose only above-ground structure is its flowering stalk. The Cistaceae are promising candidates for studies geared toward a betterunderstanding of morphological form, breeding systems, chromosomal evolution, biogeography, shrubland ecology, and host-parasite relationships; however, research has been hindered by the lack of a reliable natural classification. The family has largely been neglected taxonomically, and higher- and lower-level taxonomy remain obscure because traditional schemes have revolved around "field identifiable" vegetative and floral attributes, with little agreement on their value in defining natural groups. In the past, prevailing ideas on what constitute primitive, specialized or convergent features have produced disparate opinions on cistalean relationships. This research by graduate student Jennifer Arrington, under the direction of Dr. Paul Manos at Duke University, represents the first phylogenetic approach to the classification of the Cistaceae and the first comprehensive taxonomic treatment since 1925. In order to delimit taxa and develop a morphological matrix for evolutionary analyses, a close examination will be made of promising diagnostic traits of the flower such as the stigma, style, pollen and ovule, as well as chromosome number and developmental characteristicspertaining to merosity (number of flower parts). Samples of all the known genera and of many of the described species have been or will soon be collected from throughout the native range of the family in North America and in Europe. This information will be supplemented by molecular genealogies based on chloroplast and nuclear DNA sequences, which will provide a comparative phylogenetic framework for research on morphological form, chromosomal evolution, host-specificity, and biogeography.