Patterns of Genetic and Clonal Diversity in Myriophyllum spicatum in Streams and Reservoirs of Republic of Korea

<i>Myriophyllum spicatum</i> is a globally distributed aquatic plant capable of sexual and clonal reproduction. Despite its ecological importance and biochemical potential, studies on its genetic and clonal structure in freshwater systems throughout South Korea remain limited. We investigated the genetic and clonal diversity of <i>M. spicatum</i> using 30 newly developed microsatellite markers across 120 individuals from six freshwater systems in South Korea. Overall, 148 alleles were identified, with an average polymorphism information content value of 0.530. Clonal diversity differed among populations, with the genotypes to individuals (G/N) ratio ranging from 0.200 to 1.000. Bottlenecks and clonal dominance were observed in riverine populations. High genetic differentiation (mean F_ST = 0.556) indicated limited gene flow, and STRUCTURE analysis revealed six distinct genetic clusters. No significant correlation was found between genetic and geographic distance, suggesting possible seed dispersal by waterfowl, particularly between adjacent populations. Genetic structure was shaped by habitat type, disturbance intensity, and reproductive strategy. Stable reservoir habitats favored sexual reproduction and higher genetic diversity, whereas disturbed river systems showed clonal dominance and reduced variation. These findings provide essential genetic insights for conservation planning and sustainable management of aquatic plant resources.