Meeting Abstract

11.2  Sunday, Jan. 4  Drawing Lines in Wallacea: Historical Biogeography meets Geophysics in the Deep Sea HICKMAN, C.S.; University of California, Berkeley caroleh@berkeley.edu

The biogeographic realm of Wallacea is famous as a terrestrial biodiversity hotspot, encompassing thousands of the tropical islands of eastern Indonesia. In spite of some recent recognition of significant shallow marine endemism in the region, it is the poorly documented deep-sea (>200 m) fauna that is most closely tied to the turbulent geologic history, submarine features, and deep tectonic boundaries that define modern Wallacea. Discovery of two endemic genera and six endemic species in ancient orders of marine gastropods (Vetigastropoda: Seguenzioidea and Trochoidea) in Sulawesi and Halmahera make sense in the context of the active tectonics, double subduction, and closure of the Molucca Sea between the two islands. Is it coincidental that two relict taxa are part of a disappearing oceanic microplate that was once much larger? Is new evidence of deep-sea marine endemism in Wallacea an artifact of insufficient sampling of the bathyal and abyssal fauna of other biogeographic regions in the Indo-West Pacific? Compilation of biogeographic distributions of 60 species of deep-sea calliotropine gastropods suggests that the deep endemism in Wallacea is real. When distributions are mapped onto tectonic features and viewed over the last 200 million years, a deep marine Wallacea takes on new meaning. Modern Wallacea must be viewed as a product of fusions as well as fragmentations in the terrestrial realm and of crustal disappearance (consumption) as well as generation of new habitat in the deep marine realm. A geophysical approach to biogeography may help in developing a more effective strategy for sampling deep marine biodiversity in the Indo-West Pacific.