Understanding the distribution of Alocasia: Historical biogeography and climate niche separation in sister species pairs

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Alocasia (Araceae) comprises 87 species distributed from Sri Lanka to subtropical Australia. Most species are lowland forest understorey herbs, although a few grow on exposed sites or at elevations above 1000 m. Alocasia is most diverse on Borneo (c. 40 species), the Philippines (c. 18), and New Guinea (c. 12). Based on fossils, the larger clade to which Alocasia belongs originated in Eocene Laurasia, and a new molecular tree and molecular-dating (using data reported in this proposal) set up the hypothesis that Alocasia entered the Malesian region from the North and diversified mainly from the Miocene onwards, when warm-moist climates led to an expansion of rain forests. We will test this hypothesis with complete species sampling. For a subset of species, we will carry out climate niche modeling using MaxEnt based on present/absent data from field work in Sarawak and presence-only data from herbarium surveys in Indonesia and Malaysia (a pilot analysis has been done). Niche preferences of species pairs will be placed in the context of the dated larger phylogeny so that direction and timing of change can be inferred. This will permit assessing the relative roles of changing or conserved climate preferences in the diversification of Alocasia. We are seeking support for molecular data generation, fieldwork, and herbarium visits in Southeast Asia, which are essential for completing range data and for the description of new species.