ANALYZING GEOGRAPHIC DISTRIBUTION MODELS OF MADAGASCAR PLANT SPECIES USING GEOLOGICAL DATA TO UNDERSTAND SPECIATION

The processes driving species radiations of plants on Madagascar remain inadequately explored. A wide variety of soil types exist on Madagascar, from ferralitic soils on the east coast, to ferruginous tropical soils in the southwest, to alluvial soils in the western region. This diversity, along with the remarkable bioclimatic contrast between the eastern and western sides of the island, have long been invoked to explain Madagascar’s extraordinary microendemism. Recent patterns of speciation identified in the island’s rich fauna are complicated and suggest that many processes have contributed. We reconstructed the geographic distribution of species in the Hibiscus tribe (Malvaceae) as a first step to uncover some of the forces driving speciation on Madagascar. Using 753 georeferenced distribution records from the herbaria of MO and P, the range of 27 species were determined and adjusted with environmental niche modeling using soil type, lithology, climate, and topographic data. As a means to explore niche evolution in this plant group we used ENMTools to compare the ecological tolerances between species.