Genetic structure of Pacific crown-of-thorns starfish (Acanthaster cf. solaris) in southern Japan based on genome-wide RADseq analysis

Pacific crown-of-thorns starfish (Acanthaster cf. solaris) are known to be widely distributed, and previous studies (showing limited genetic structure) suggest that there are high levels of connectivity at regional scales. It is possible, however, that methods used in previous studies (e.g., microsatellites) did not effectively resolve genetic differentiation and structure for crown-of-thorns starfish. This study examined patterns of genetic structure for populations of the A. cf. solaris in the Ryukyu Archipelago and at Miyazaki, Japan, using restriction-site-associated DNA sequencing (RADseq) analysis, to identify genome-wide single nucleotide polymorphism (SNP) loci to examine genetic diversity and gene flow of CoTS populations. We obtained 186 biallelic SNPs completely shared among 33 individuals by utilizing the published genome sequence of CoTS. Population genomic analysis with biallelic SNPs confirmed that there is limited genetic differentiation and seemingly strong connectivity and gene flow among CoTS populations in the Ryukyu Archipelago and at Miyazaki, Japan. Our findings likely reflect the rapid range expansion of CoTS through southern Japan or panmixia facilitated by the northward flowing Kuroshio Current.