GENETIC-STRUCTURE OF CROWN-OF-THORNS STARFISH (ACANTHASTER-PLANCI) IN AUSTRALIA

Significant genetic structuring is reported for crown-of-thorns starfish Acanthaster planci (L.) populations within Australia, sampled in 1987 and 1989, with Eastern Australian and Western Australian populations forming different groups. Eastern Australian populations sampled included the three most southerly, on isolated reefs of Elizabeth and Middleton Reefs, and Lord Howe Island. The Lord Howe Island population formed a discrete outlier from all other Australian populations, with average genetic distances (Nei's unbiased D) from other populations of 0.05 compared with 0.01 among all other populations. This is greater than the levels of genetic differentiation described for A. planci from sites at the extremes of the Pacific. The genetic distinction of Western Australia and Lord Howe Island is considered to reflect restricted dispersal as a result of current patterns. The Western Australian populations also showed less genetic diversity than the Great Barrier Reef populations, and this might reflect a founder effect or recent bottleneck in the Western Australian populations.