Detection and dispersal risk of genetically disturbed individuals in endangered wetland plant species Pecteilis radiata (Orchidaceae) in Japan

Genetic disturbance is propagated by artificial reinforcement or reintroduction of organisms from populations whose genetic structure is sufficiently different from the original populations. Many cultivars were produced from wild plant species, and fears exist that genetic disturbance of wild populations occurred by the human migration of cultivars. In this study, we detected genetic disturbance in Pecteilis radiata [= Habenaria radiata] (Orchidaceae) in the Hyogo Prefecture of Japan using multiplexed inter-simple sequence repeat genotyping by sequencing (MIG-seq). Also, we estimated the risk of the spread of genetically disturbed individuals based on the results of spatial genetic structure and gene flow. In five out of 33 examined sites, we detected genetically disturbed individuals that possessed the same genetic cluster as cultivar samples. No spatial genetic structure was found among the sites within a 0.64 km radius, which indicated that pollen or seeds of P. radiata freely migrated among these populations. Consequently, we demonstrated that a risk exists of spreading genetic disturbances by gene flow within a radius of 0.64 km from the site where genetic disturbance was found. Raised public awareness of the risk of genetic disturbance would be necessary to prevent additional spread of genetic disturbances by human activities.