Biodiversity, phylogeny and biogeography of African and Madagascan Melastomataceae

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The pantropical Melastomataceae s.l. (172 gen., 4800-5000 spp.) rank among the ten largest angiosperm families. They can be recognized by their acrodromous leaf venation and beautiful flowers with mostly poricidal and conspicuously ornamented stamens. African members of Melastomataceae are notoriously understudied and only scarcely represented in molecular studies. Melastomateae is the most diverse tribe in Africa with ca. 185 species in 13 genera, while Madagascar has about 70 species in nine genera. A detailed molecular study of neotropical Melastomateae showed that the paleotropical genera form a monophyletic lineage originating from neotropical ancestors. Dissotis, currently the largest genus (120 spp.) in the Afro-Madagacan Melastomateae, seems to be polyphyletic. Despite, the high diversity of Afro-Madagascan Melastomateae, only 17 species have so far been included in molecular phylogenetic studies. Due to the lack of a comprehensive morphological and molecular treatment, the relationships among African, Madagascan, and Asian genera of Melastomateae are incompletely resolved and their morphological and biogeographical evolution is poorly understood. The main objective proposed for this research project is to resolve generic relationships in the African-Madagascan Melastomateae based on a dense taxon sampling comprising 160 accessions representing 120 species and all genera in Africa and Madagascar (and selected representatives from Asia) and sequencing of multiple fast-evolving genomic regions complemented by a careful morphological and geographical survey of the lineage based on the study of herbarium specimens. Since further evolutionary studies in Melastomateae depend on a deep taxonomical understanding of this largely unknown African lineage the systematic groundwork will be our first prime goal. Then the molecular trees will be used to reconstruct divergence times, geographical and morphological diversification of paleotropical Melastomateae. The inclusion of proposed paleoendemics such as Cailliella, Pseudosbeckia, Dionychastrum and Nerophila, will contribute to our understanding of the origin and spread of Melastomateae in Africa and Madagascar. Studies of floral morphology in the group will focus on stamen morphology and the evolution of heteranthery which has a direct (and probably fast) impact on the pollination syndrome and might represent one key character for diversification in the group. Our results will have a strong and direct impact on planned floristic treatments of the family, e.g. in the ongoing treatment of the Flora of Central Africa and in updating the Floras of Cameroon and Gabon, and therefore contribute to the floristic biodiversity survey of these regions.