Molecular Evidence Reveals the Sympatric Distribution of Cervus nippon yakushimae and Cervus nippon taiouanus on Jeju Island, South Korea

SIMPLE SUMMARY: The sika deer (Cervus nippon) was introduced in South Korea from Japan and Taiwan for commercial farming. They have become invasive to mainland South Korea and Jeju Island due to escape from confinement and illegal release. Native species and ecosystems may be threatened by the presence of non-native species. To deal with ecological risk and evolutionary processes, information on the phylogeny of these non-native sika deer is necessary. Genetic studies using mitochondrial DNA cytochrome B (CytB) gene sequences were conducted to determine the subspecies of Jeju sika deer and their phylogenetic relationship. On Jeju Island, we confirmed the presence of two distinct groups of CytB haplotypes: Cervus nippon yakushimae, native sika to Japan, and Cervus nippon taiouanus, native to Taiwan. ABSTRACT: Non-native species threaten native ecosystems and species, particularly on islands where rates of endemism and vulnerability to threats are high. Understanding species invasion will aid in providing insights into ecological and evolutionary processes. To identify the non-native sika deer (Cervus nippon) population in Jeju, South Korea, and their phylogenetic affinities, we collected tissue samples from roadkill and the World Natural Heritage Headquarters in Jeju. Mitochondrial DNA cytochrome B (CytB) gene sequences were analyzed to determine two distinct CytB haplotypes. Phylogenetic analysis using maximum likelihood tree revealed two haplotypes of CytB clustered into two different groups representing two subspecies: C. n. yakushimae, native to Japan, and C. n. taiouanus, native to Taiwan. The tentative divergence time between the two subspecies was estimated at 1.81 million years. Our study confirmed that the two subspecies of sika deer are sympatric in the natural ecosystem of Jeju Island. This study provides valuable information to help government and conservation agencies understand alien species and determine control policies for conserving native biodiversity in South Korea.