Genetic diversity assessment of Nannophya pygmaea populations inhabiting spring-fed marshes in Kani, Japan

The small dragonfly Nannophya pygmaea Rambur 1842 (Libellulidae) inhabits spring-fed marshes in Kani, Japan. To support the conservation of the genetic diversity of the N. pygmaea population, its genetic diversity and genetic differentiation were assessed by comparing the sequences of a 658-bp-long fragment of the mitochondrial DNA cytochrome c oxidase subunit I gene. Based on DNA polymorphisms in the gene, the 294 N. pygmaea specimens collected in this study were divided into eight haplotypes. There was no significant correlation between haplotype diversity and area and slope of the marshes, pH and electric conductivity of surface water, or vegetation height around the marshes. Furthermore, there was no significant genetic differentiation between marshes, and the N. pygmaea population was considered to be a single population that migrates among marshes without gene exchange restriction. To maintain the genetic diversity of the N. pygmaea population, it is necessary to prevent the decline of habitat suitability and the loss of marshes, which could limit gene exchange. Therefore, we will continue to monitor the water quality and sediment inflow of the marshes and remove accumulated sediment and plants that invade from the surrounding area, as well as periodically evaluate the genetic diversity of the N. pygmaea population.