GENETIC CONSEQUENCES OF LONG LARVAL LIFE IN THE STARFISH LINCKIA-LAEVIGATA (ECHINODERMATA, ASTEROIDEA) ON THE GREAT-BARRIER-REEF

Gene flow between populations of the asteroid Linckia laevigata (Linna eus) was investigated by examining over 1000 individuals collected fro m ten reefs throughout the Great Barrier Reef (GBR), Australia, for ge netic variation at seven polymorphic enzyme loci. Despite geographic s eparations in excess of 1000 km, Nei's unbiased genetic distance (0 to 0.003) and standardised genetic variation between populations (F(ST)) values (mean 0.0011) were small and not significant. Genetic homogene ity among L. laevigata populations is consistent with the long-distanc e dispersal capability of its 28 d planktonic larval phase, and is gre ater than that observed for other asteroid species, including another high-dispersal species, Acanthaster planci, which has a 14 d larval ph ase. Variation within populations was also higher than previously reco rded for asteroids (mean heterozygosity = 0.384; number of alleles per locus ranged from 5.1 to 6.0 in each population). Among asteroids, di spersal ability is positively correlated with gene flow and levels of variation, and negatively correlated with levels of differentiation.