Population Genetic Structure of Giant Clams, Tridacna gigas (Family Tridacnidae), on the Great Barrier Reef

Abstract

The Great Barrier Reef (GBR) is one of the few remaining Pacific reef systems where the giant clam, Tridacna gigas, can be found in large numbers. Genetic data from Inter-Simple Sequence Repeat loci (ISSR) suggest low levels of genetic structuring among four north-central GBR populations (PhiPT = 0.0322, p = 0.005), with significant genetic differences evident between populations from Thetford and Grub Reefs. The data suggests a weak correlation of genetic differentiation among populations and their linear distance of geographical separation. The region of the GBR sampled here is approximately a quarter of the total distribution of T. gigas. Significant genetic structuring may therefore be present between northern and southern GBR T. gigas populations and consequently, a conservative approach should be practiced relating to the translocation of this species throughout the GBR.