SUMMARY
Genetic diversity has an important role in the stability of coral populations in coping with disturbances. In the last three bleaching events, the coral Echinopora lamellosa survived better in the eastern- than the western- Lombok waters that are not related to algal symbiont diversity. The present study aimed to assess the genetic diversity of E. lamellosa from the two locations in the Lombok waters. The ITS1-5.8S-ITS2 (whole ITS region) marker was used to identify and to determine the genetic structure, genetic variation, and demographic pattern of E. lamellosa. The results showed that E. lamellosa of the two locations are two different populations. The haplotype diversity was very high indicating a predominance of sexual reproduction mode for both eastern and western populations. The phylogenetic topology suggests there is possible connectivity between populations, whereas the haplotype network exhibits a restricted gene flow between the two populations. The results suggest that the present E. lamellosa populations were from both surviving colonies and new recruitment of long-distance larvae. Both population likely shares the same larvae supply brought from source-reefs in the Flores Sea or Makassar Strait by the Indonesian Throughflow. The present and previous studies revealed that genetic diversity alone yet to explain the resistance of E. lamellosa in eastern and western Lombok waters.