DRP007308
Integrated analysis of genome-wide population genetic analysis and numerical simulation to estimate larval dispersal of Acanthaster cf. solaris between Ogasawara and other Japanese populations
Many benthic marine invertebrates have pelagic larval duration (PLD) to disperse. Larval dispersal is essential for maintaining each population, and thus assessment of larval dispersal is significant for conservation management. Direct observation of larval dispersal is, however, challenging. Large scale larval dispersal is often estimated by indirect methods such as population genetic analysis and oceanographic numerical simulation analysis. While each indirect method has advantage and disadvantage to be compensated, not many studies have simultaneously estimate larval dispersal. In this study, we estimated larval dispersal between Kuroshio and Ogasawara regions using both novel population genomic method and oceanographic dispersal simulation based on Global HYCOM. Our target species Acanthaster cf. solaris, is a coral predator and its outbreaks are the major threat in coral reef conservation. While successive population outbreaks via larval dispersal have been reported along Kuroshio regions, first semi- population outbreak of A. cf. solaris was observed in Ogasawara in 2018. The aim of the study was to assess if the population outbreak in Ogasawara is directly attributed to large scale larval dispersal from Kuroshio region. Population genetic analysis revealed overall genetically homogenized patterns among Ogasawara and the other Japan populations, suggesting genetic composition of Ogasawara is similar to Kuroshio regions. On the other hand, 26-years oceanographic dispersal simulation indicated larvae are mostly self-seeded in Ogasawara populations and hard to reach from Kuroshio region within one generation. However, from genetic mixture analysis based on a connectivity matrix produced by the larval dispersal simulation with assuming Markov chain, gene flow from the Kuroshio region to Ogasawara through the stepping-stone pass was revealed. The gene from the Kuroshio region gradually intruded into the Ogasawara population with the Markov chain time-step, and genetic variations between the Kuroshio region and Ogasawara became almost homogenized after 500 time-step. These results suggest while large scale larval dispersal from outbreaking Kuroshio population to Ogasawara population within one generation is unlikely, stepping-stone larval dispersal could occur from Kuroshio population to Ogasawara within multiple generations that led observed genetically homogenized patterns. This study highlighted the importance of using both genetic and oceanographic methods to estimate larval dispersal that provides significant insight into larval dispersal that occurs in ecological and evolutionary time scale.
Many benthic marine invertebrates have pelagic larval duration (PLD) to disperse. Larval dispersal is essential for maintaining each population, and thus assessment of larval dispersal is significant for conservation management. Direct observation of larval dispersal is, however, challenging. Large scale larval dispersal is often estimated by indirect methods such as population genetic analysis and oceanographic numerical simulation analysis. While each indirect method has advantage and disadvantage to be compensated, not many studies have simultaneously estimate larval dispersal. In this study, we estimated larval dispersal between Kuroshio and Ogasawara regions using both novel population genomic method and oceanographic dispersal simulation based on Global HYCOM. Our target species Acanthaster cf. solaris, is a coral predator and its outbreaks are the major threat in coral reef conservation. While successive population outbreaks via larval dispersal have been reported along Kuroshio regions, first semi- population outbreak of A. cf. solaris was observed in Ogasawara in 2018. The aim of the study was to assess if the population outbreak in Ogasawara is directly attributed to large scale larval dispersal from Kuroshio region. Population genetic analysis revealed overall genetically homogenized patterns among Ogasawara and the other Japan populations, suggesting genetic composition of Ogasawara is similar to Kuroshio regions. On the other hand, 26-years oceanographic dispersal simulation indicated larvae are mostly self-seeded in Ogasawara populations and hard to reach from Kuroshio region within one generation. However, from genetic mixture analysis based on a connectivity matrix produced by the larval dispersal simulation with assuming Markov chain, gene flow from the Kuroshio region to Ogasawara through the stepping-stone pass was revealed. The gene from the Kuroshio region gradually intruded into the Ogasawara population with the Markov chain time-step, and genetic variations between the Kuroshio region and Ogasawara became almost homogenized after 500 time-step. These results suggest while large scale larval dispersal from outbreaking Kuroshio population to Ogasawara population within one generation is unlikely, stepping-stone larval dispersal could occur from Kuroshio population to Ogasawara within multiple generations that led observed genetically homogenized patterns. This study highlighted the importance of using both genetic and oceanographic methods to estimate larval dispersal that provides significant insight into larval dispersal that occurs in ecological and evolutionary time scale.