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Tusso S, Morcinek K, Vogler C, Schupp PJ, Caballes CF, Vargas S, Woerheide G.2016. Genetic structure of the Crown-of-Thorns seastar in the Pacific Ocean, with focus on Guam. PeerJ Preprints4:e1167v3https://doi.org/10.7287/peerj.preprints.1167v3
Population outbreaks of the corallivorous crown-of-thorns seastar (COTS), Acanthaster ‘planci’ L., are among the most important biological disturbances of tropical coral reefs. Over the past 50 years, several devastating outbreaks have been documented around Guam, an island in the western Pacific Ocean. Previous analyses have shown that in the Pacific Ocean, COTS larval dispersal may be geographically restricted to certain regions. Here, we assess the genetic structure of Pacific COTS populations and compared samples from around Guam with a number of distant localities in the Pacific Ocean, and focused on determining the degree of genetic structure among populations previously considered to be isolated. Using microsatellites, we document substantial genetic structure between 14 localities from different geographical regions in the Pacific Ocean. Populations from the 14 locations sampled were found to be structured in three significantly differentiated groups: (1) all locations immediately around Guam, as well as Kingman Reef and Swains Island; (2) Japan, Philippines, GBR and Vanuatu; and (3) Johnston Atoll, which was significantly different from all other localities. The most stark divergence of these groupings from previous studies is the lack of genetic differentiation between Guam and extremely distant populations from Kingman Reef and Swains Island. These findings suggest potential long-range dispersal of COTS in the Pacific, and highlight the importance of ecological determinants in shaping genetic structure.
This version has been modified after peer review.
Predicted allelic richness in function of sample size
Predicted allelic richness in function of sample size. Each line represents sampled localities. Localities with the lowest and highest allelic richness are shown in red and blue respectively, with their variance in dash lines.
Genetic diversity estimates for 10 microsatellite loci all the localities
Genetic diversity estimates for 10 microsatellite loci all the localities. N number of individuals, Na number of allele per locus, Ar allelic richness, Ho observed heterozygosity, He expected heterozygosity, FIS inbreeding coefficient.