The evolutionary origin of Madagascar's amazingly rich biodiversity remains a great unknown. Almost every group of organisms occurring on the island is exceptionally diverse and often unique to the island. Noronhia, the Madagascar olive, exemplifies this situation and serves as a model for understanding plant diversification on the island. This project seeks to evaluate diversification in Noronhia through: 1) reassessment of species boundaries and generic diversity based on morphological data; 2) inference of evolutionary history and phylogenetic relationships using DNA sequences, and; 3) examination of morphology, phylogenetic relationships, and ecology among species co-occurring in a single locality.
Protecting the Malagasy biota is a challenging endeavor when the human struggle for daily subsistence largely outweighs the need for conservation and more scientific investigation. Results from this study, disseminated among conservation agencies and through peer-reviewed journals and scientific conferences, will provide a sound taxonomic framework on which to base an effective conservation strategy. This study of Noronhia will help us to understand the radiation of an ecologically important Malagasy plant genus and databases of herbarium specimens, morphological characters, and DNA sequences will be made available to the public.
Cynthia Hong-Wa studied Noronhia, a member of the olive family found only in Madagascar and the surrounding islands, to help understand plant species diversification. She wanted to know the relationships of the genus and how many species it contained, and she also wanted to understand how different species of the genus were able to live together in the same place. Madagascar is noted for its unique flora and fauna, and Noronhia is a distinctive genus known only from the island and some small islands nearby. Cynthia visited the island collecting material for her work, and she also studied an area in which several species of Norohnia were growing together. Using both the material she collected, and also that collected on mainland Africa by Guillaume Besnard, who collaborated in part of her work, she analyzed the DNA of some genes, and this allowed her to determine the relationships among her species. What she found was rather surprising. Some other species from Madagascar previously included in other genera needed to be placed in Noronhia. Furthermore, it appears that Noronhia represents a single migration from Africa to Madagascar, and that the evolution of species on Madagascar has been quite quick. Another thing she was interested in was finding out how many species there were in Noronhia. Measuring features of leaves, flowers, and fruits of herbarium specimens others had collected over the years and those that she collected, she amassed a large amount of data. She analysed this data to see what groups of specimens could be recognised, and where possible she compared these groups with the groups she obtained from her analysis of the DNA data. She also took the geographic distribution of the groups into account, and also other characters that she was unable to include in her analysis, and all told she recognized about 65 species, one third of which were unknown to science. Although this part of the work is not quite finished - this alone would have been more than enough for a thesis - she is preparing a monograph on the whole genus. She is able to make species descriptions of her species directly from the data she collected, which is not often done. When she publishes this part of the work, the data will be placed in a public repository, and anybody will be able to use them, and this will help the additiional species that still remain undiscovered to be described more quickly and efficiently. When she visited the area in the north of the Island where several species of Noronhia grew together, she used the ecological observations that she made there to help understand how these species - closely related, yet each different - were able to live together; this is a cental question in biology. Indeed, there are many more species in the genus than realised, and this makes the genus a particularly good example of the species radiations that make the plants of Madagascar so distinctive. Her work will also be the basis for assessing the conservation status of the individual species of Noronhia in Madagascar, as well as a tool for identifying potential sites for conservation. Moreover, outreach activities carried out in Madagascar during the course of the project such as supervising students, providing a workshop on field techniques and plant identification for undergraduate students at the University of Antsiranana (North Madagascar), will help bridge the gap between the public in Madagascar and the scientific community on topics relating to the environment, scientific research and education.
