GENETIC-EVIDENCE OF CLOSED LIFE-CYCLES FOR SOME CORAL-REEF FISHES WITHIN TAIARO LAGOON (TUAMOTU ARCHIPELAGO, FRENCH-POLYNESIA)

Taiaro Lagoon has no permanent or regular connection with the ocean (i ngress is restricted to episodes of high sea-level and/or strong wave action) raising the question of how fish populations with normally dis persive larvae are maintained inside this lagoon. We compared the gene tic population structures of two coral reef fishes, Acanthurus trioste gus and Chaetodon ulietensis, present on both sides of the atoll rim t o determine whether there is evidence of reproductive isolation. Genet ic surveys showed that the lagoonal and oceanic populations were stati stically different at five loci (AAT-3, GDA*, HPD*, MDH* and SDH*) in A. triostegus and three loci (PGI-2, IDH* and PGD*) in C. ulietensis , producing high F-st values of 0.055 and 0.021, respectively. Our gen etic and demographic data on these species suggest that both may be co mpleting their life-cycles inside the lagoon, which leads us to questi on the common assumption that coral reef fishes require oceanic condit ions for larval development.