Evolution, 55(5), 2001, pp. 1029±1039 PHYLOGEOGRAPHY OF THE TRUMPETFISHES (AULOSTOMUS): RING SPECIES COMPLEX ON A GLOBAL SCALE B. W. BOWEN,1,2 A. L. BASS,1 L. A. ROCHA,1 W. S. GRANT,3 AND D. R. ROBERTSON4 1Department of Fisheries and Aquatic Sciences, University of Florida, 7922 NW 71st Street, Gainesville, Florida 32653 2E-mail:
[email protected]¯.edu 3International Center for Living Aquatic Resource Management, P.O. Box 500, GPO, Penang 10670, Malaysia 4Smithsonian Tropical Research Institute, Balboa, Panama E-mail:
[email protected] Abstract. The distribution of circumtropical marine species is limited by continental boundaries, cold temperate conditions, and oceanic expanses, but some of these barriers are permeable over evolutionary time scales. Sister taxa that evolved in separate ocean basins can come back into contact, and the consequences of this renewed sympatry may be a key to understanding evolutionary processes in marine organisms. The circumtropical trumpet®shes (Au- lostomus) include a West Atlantic species (A. maculatus), an Indian-Paci®c species (A. chinensis), and an East Atlantic species (A. strigosus) that may be the product of a recent invasion from the Indian Ocean. To resolve patterns of divergence and speciation, we surveyed 480 bp of mitochondrial DNA cytochrome b in 196 individuals from 16 locations. Based on a conventional molecular clock of 2% sequence divergence per million years, the deepest partitions in a neighbor-joining tree (d 5 0.063±0.082) are consistent with separation of West Atlantic and Indian-Paci®c species by the Isthmus of Panama, 3±4 million years ago.