The population genetic structure of a common tropical damselfish on the Great Barrier Reef and eastern Papua New Guinea

Understanding patterns of connectivity in marine species is vital for the management and conservation of marine biodiversity. Here, the population genetic structure of a common and abundant tropical reef damselfish, Pomacentrus amboinensis, is reported. Using nine polymorphic microsatellite loci, the genetic structure at both small (i.e., around Lizard Island, Great Barrier Reef [GBR]) and large (GBR and Papua New Guinea [PNG]) spatial and temporal scales (2-1,600 km; 28 days- 6 years; n = 1,119) was analyzed. Temporal analyses found no evidence of genetic differentiation within or between Lizard Island recruitment pulses (R (ST) = -0.001, P = 0.788), or corresponding established adult populations separated by 6 years of sampling (R (ST) = 0.003, P = 0.116). The spatial analysis revealed that P. amboinensis populations are largely panmictic on the GBR and eastern PNG (R (ST) = 0.001, P = 0.913), the only genetic discontinuity being between Kimbe Bay to the north of PNG and all populations south of PNG (R (ST) = 0.077, P < 0.0001). Despite assumed high levels of self-recruitment based on previous tagging studies (15-60%), data presented here indicate that enough recruits are dispersing to impede the evolution of genetic structure over distances as great as 1,600 kms in this species. Data therefore indicate that the temporal genetic stability recorded here is maintained by high levels of gene flow.