Recent rapid climate change caused by global warming has significantly impacted organisms. Especially, tropical marine organisms increasingly have been reported in temperate zones. Previously, only two species of ghost crabs, Ocypode stimpsoni and O. cordimanus, had been reported in South Korea, but our research team has newly found two tropical ghost crab species, O. sinensis and O. ceratophthalma, in the temperate region of South Korea. Surprisingly, for O. ceratophthalma, our study confirmed that the Yeongdeok region of the East Sea in South Korea represents the northernmost distribution of this species, based on recent research. To find possible evidence of range expansion driven by climate change, we conducted a comparative analysis of the key morphological and genetic characteristics of the species discovered in this study. The genetic analysis of two individuals of O. sinensis was performed using mitochondrial whole genome sequencing and phylogenetic analysis based on 13 protein-coding genes (PCGs). For a total of 67 O. ceratophthalma individuals, a genetic population structure analysis was conducted to assess genetic connectivity with East Asian populations. The phylogenetic analysis of O. sinensis indicated that the temperate species O. stimpsoni is more closely related to the tropical species O. ceratophthalma than O. sinensis is to O. ceratophthalma. Comparing using mitochondrial and nuclear gene sequences, the Korean populations of O. ceratophthalma showed low genetic differentiation from neighboring populations. Given the oceanic flow of the Kuroshio current and smaller currents branching off, the genetic homogeneity of the species is anticipated to be a result of continuous immigration from the same potential source population around Taiwan or more southern localities. Our findings may imply that they provide insight into understanding the habitat-expanding or shifting range of tropical crabs in the temperate zone.

climate change, temperate zone, benthic fauna, tropical ghost crab, genetic analysis