NSFDEB-NERC Origins and expansion of endemic biodiversity in western Melanesia and their relation to tectonic evolution

Western Melanesia-including New Guinea-sits at the crossroads of Asia and Australia and is one of the most interesting, puzzling, and understudied hyperdiverse regions on Earth. Clarifying how tectonic movements have sundered or joined different Melanesian landforms in the past several million years is key to understanding the origins of this biotic diversity. The intent of this project is to elucidate how the diversity and evolutionary history of the five major geological landforms that comprise most of western Melanesia have impacted evolution of that region's biota and to identify those ancient insular landmasses critical in the origin of lineages that colonised and radiated across New Guinea, Australia, and/or insular Asia. To meet this goal, we will construct dated phylogenetic trees on a multitude of reptile and amphibian (herpetofauna) lineages having different dispersal abilities, times of origin, and natural histories that span the five major landmasses of western Melanesia. We will use the dates and relationships recovered to identify areas and times of origin for each clade and trace their expansion to new regions. Cross-validation between these results and updated geological models will illuminate tectonic events that drove speciation and dispersal in the region. We use herpetofauna to address these questions because their variable but moderate trans-marine dispersal abilities allow them to better track geological history than do taxa having much greater (e.g., birds) or lesser (e.g., land snails) dispersal capabilities. This research will help to replace the outdated, unidirectional "out-of-New-Guinea" model for origins of Pacific biodiversity with a more dynamic and nuanced understanding that ancient, yet under-appreciated, land areas in Melanesia have long been important in shaping biotic evolution in the broader region.