Pachypodium (Apocynaceae)

Molecular Phylogenetics of the plant genus Pachypodium (Apocynaceae)

The genus Pachypodium contains 21 species of succulent, perennial plants distributed in southern Africa (5 species) and Madagascar (16 species). Pachypodium is known for its diverse and intriguing array of growth forms, including geophytes, shrubs, and small trees. Because of their unusual growth forms and colorful, showy flowers, many species of Pachypodium are prized ornamentals with a long history of cultivation as well as exploitation in the wild. The diversity of form noted within the genus Pachypodium may result from the geologically and climatically diverse array of habitats to which the species are adapted, ranging from montane grassland to coastal dry forest. The wide and disjunct geographic range of Pachypodium also indicates a long history of migration and diversification within southern Africa and Madagascar. However, because little is known about evolutionary relationships within the genus, it is difficult to determine the geographic history of Pachypodium or reconstruct the evolution of morphological and ecological characters such as growth form and habitat preference. My research on Pachypodium uses molecular phylogenetic trees to learn about the evolutionary and distributional history of this diverse and intriguing genus, with an emphasis on the interaction of ecological and morphological traits during the diversification of the genus. Molecular phylogenetic information will also be used to develop conservation recommendations for individual species of Pachypodium, many of which are threatened by habitat loss and over-collection.