The Lobeliaceae are a medium-sized plant family comprising 31 genera, with just under1,200 species distributed worldwide, and the Cyphiaceae sensu stricto comprise the genus Cyphia with 74 species in Africa. These families are classified in the order Campanulales, along with the Campanulaceae sensu stricto and four New World cyphioid genera. Molecular and morphological data support the monophyly of the Lobeliaceae, with Cyphia identified as the most closely related genus. The Lobeliaceae were monographed as part of Das Pflanzenreich, but this classification is largely artificial, in part because Lobelia constitutes the paraphyletic 'core genus' of the family, from which the segregate genera evolved. This investigation is generating chloroplast DNA sequence data from the genes atpB, rbcL, and the intergenic spacer for 120 representative species. The resulting phylogenetic estimate is being used to (1) produce a phylogenetically-based classification of these plants, (2) reconstruct the morphological evolution responsible for the origin of the segregate genera, and (3) reconstruct the major events in the biogeographic history of these plants. The Campanulales are also of interest because of the large number of rearrangements that have occurred in their chloroplast DNA. Previous work indicates that these rearrangements are not simply rare, random events. A genetic element is present that causes the rearrangements, and there is evidence of high-level functional constraint in chloroplast DNA evolution that favors preservation of the ancestral genome organization. This work uses (1) Southern blot analysis to produce detailed maps of the chloroplast DNA arrangements, (2) PCR-based confirmation of the rearrangements, and (3) DNA sequencing of the rearrangement regions to differentiate independent rearrangements that have occurred in a given region of the DNA molecule. These rearrangements provide additional evidence of phylogenetic relationships, and these relationships simultaneously provide a framework for understanding chloroplast genome evolution, with broad implications for plant biology. The results of this research are being compared with similar studies conducted by other investigators of the Campanulaceae and the New World cyphioids.
