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Holland & Cowie - Evolutionary Patterns in Pacific Amber Snails (Succineidae): the Relative Roles of Vicariance and Dispersal in Diversification

Evolutionary Patterns in Pacific Amber Snails (Succineidae): the Relative Roles of Vicariance and Dispersal in Diversification

and Island Biogeography

Center for Conservation Research & Training,

Pacific Biosciences Research Center, University of Hawaii, 3050 Maile Way, Gilmore 408, Honolulu, HI 96822, USA,

bholland@hawaii.edu

Our work applies a molecular approach to investigate origins and patterns of biological diversity in endemic Pacific land snails. In this study we seek to understand patterns of dispersal and diversification in Pacific succineid snails, focusing on the diverse Hawaiian assemblage. Preliminary results inferred from mitochondrial (COI, 16S) and nuclear (H3) markers suggest 1.) a complex colonization history in Hawaii, including multiple primary colonization events from non-Hawaiian sources; 2.) examples of adherence to as well as violation of the progression rule pattern of colonization from older to younger Hawaiian islands; 3.) evidence of colonization by an endemic Hawaiian lineage into the South Pacific; and 4.) unexpected patterns of inter-island relationships. Many Pacific islands, including the Hawaiian archipelago, arose in situ as the Pacific plate moves over a stationary hot spot. Thus, while local vicariant events within island chains, such as fragmentation of large 'super islands' into smaller ones by emergence and submergence of land bridges resulting from the dynamic processes of formation, subsidence, and erosion of islands as they move away from the hot spot, all play important short-term roles in lineage isolation, dispersal is a key process in diversification of Pacific island succineid land snails over the long-term. Molecular evidence suggests that long-distance oceanic dispersal and colonization of the Hawaiian islands has been rare but important, whereas inter-island dispersal has been far more common, but has not always resulted in lineage splitting. Our results demonstrate that oceanic dispersal should not be viewed as a trivial biogeographical phenomenon and suggest that its importance has been underestimated.


next up previous
Next: Jung et al. - Up: Special Symposium - Pacific Previous: Hickman - Geologic and
Peter Roopnarine 2005-04-12