Gene flow at three spatial scales in a coral reef fish, the three-spot dascyllus, Dascyllus trimaculatus

Dispersal in coral reef fishes occurs predominantly during the larval plank tonic stage of their life cycle. With relatively brief larval stages, damse lfishes (Pomacentridae) are likely to exhibit limited dispersal. This study evaluates gene flow at three spatial scales in one species of coral reef d amselfish, Dascyllus trimaculatus. Samples were collected at seven location s at Moorea, Society Islands, French Polynesia. Phylogenetic relationships and gene how based on mitochondrial control region DNA sequences between th ese locations were evaluated (first spatial scale). Although spatial struct ure was not found, molecular markers showed clear temporal structure, which may be because pulses of settling larvae have distinct genetic composition . Moorea samples were then compared with individuals from a distant island (750km), Rangiroa, Tuamotu Archipelago, French Polynesia (second spatial sc ale). Post-recruitment events (selection) and gene flow were probably respo nsible for the lack of structure observed between populations from Moorea a nd Rangiroa. Finally, samples from six Indo-West Pacific locations, Zanziba r, Indonesia, Japan, Christmas Island, Hawaii, and French Polynesia were co mpared (third spatial scale). Strong population structure was observed betw een Indo-West Pacific populations.