MEYER, Christopher P., Museum of Paleontology and Dept. of Integrative Biology, Univ. of California, Berkeley, CA 94720-4780
Why is the Indo-Pacific the most diverse marine biogeographic province? What geographical settings and modes of speciation lead to such extremely high species diversity? How do widespread taxa with high dispersal capabilities get sufficient genetic isolation to undergo speciation? Ideas concerning the mechanisms of diversification in the Indo-Pacific have shifted from proposing one or several competing dominant mechanisms to a more pluralistic view that multiple arenas and speciation modes are involved. Although a number of proposals have been offered concerning both the origin and pattern of this high biodiversity, as of yet, there are no comprehensive phylogenetic tests of diverse groups that have the power to falsify any of the purported evolutionary scenarios.
Cowries epitomize the large and rapid evolutionary radiations that so characterize the region. If all species are considered equally, cowries support the current mosaic view of diversification in the Indo-Pacific. However, a phylogeny of all living species based upon both morphological and molecular sequence data shows phylogeographic patterning. 148 species endemic to the Indo-Pacific have been derived from fifteen independent lineages. Within these lineages, the geographical patterning of the diversification is different for various clades. For example, some lineages exhibit remarkable peripheral endemism while others have diversified within the Western Pacific arena. Such complete phylogenetic approaches to diversification are critical to unraveling Indo-Pacific speciation processes in both time and space.