Abstract

Assiminea hiradoensis (Assiminidae, Gastropoda), a species native to Northeast Asia, is currently classified as Near Threatened (NT) on the Korean national Red List due to its restricted distribution and vulnerability to environmental changes. Given the threats posed by habitat degradation, including coastal development and climate change, understanding the genetic diversity and structure of A. hiradoensis populations is essential for its conservation. Between 2022 and 2023, we collected 113 A. hiradoensis individuals from 12 brackish coastal areas across Korea to examine the genetic diversity and population based on COI. Additionally, we incorporated two COI sequences from populations in Japan and China, retrieved from NCBI. A total of 34 unique COI haplotypes were identified from 115 A. hiradoensis individuals. Phylogenetic, TCS network, and PCoA analyses revealed weak spatial genetic structure among populations, suggesting that gene flow between populations is limited. However, relatively high genetic diversity was observed within local populations, indicating that these populations may be genetically distinct from each other. The localized genetic diversity appears to be influenced by specialized environmental factors specific to each site, as reflected in the analysis of molecular variance (AMOVA), which indicated that the majority of genetic variation occurs within populations rather than between them. These findings underscore the importance of conserving localized brackish coastal habitats, as they play a pivotal role in maintaining the genetic diversity of A. hiradoensis. In conclusion, this study highlights the urgent need for targeted conservation strategies to protect the specialized brackish coastal habitats of Northeast Asia.