Hee-Joo ChoiP, Tae-Hee Kim, Ye-Rim Choi, Hee-Young Gil*

Division of Forest Biodiversity, Korea National Arboretum, Pocheon, Korea

The genus Sorbus L. s.s. (Rosasece) comprises approximately 90 species, with five species occurring in Korea. S. commixta is widely distributed across East Asia, including Korea, Japan, the Kuril Islands, and Sakhalin (Russia), while S. ulleungensis is endemic to Ulleung Island. S. ulleungensis has recently been recognized as a distinct species from S. commixta based on morphological characteristics. A chloroplast-based molecular study further provided preliminary evidence for genetic divergence between these two species. In this study, we used a genome-wide 3RAD-seq approach to (1) compare the genetic structure of S. commixta and S. ulleungensis, and (2) examine regional genetic differentiation within S. commixta across Korea. We analyzed 10 populations (94 individuals) of S. commixta from Korean native habitats and one population (8 individuals) of S. ulleungensis from Ulleung Island. Based on a total of 45,933 single nucleotide polymorphisms (SNPs), population structure analyses (admixture, ML tree and PCA) revealed clear genetic differentiation between the two species, consistent with the previous chloroplast-based study. Within S. commixta, regional genetic clusters were detected among Korean populations, despite the bird-mediated seed dispersal of berry-like pomes. This geographic genetic structure may be attributed to the habitat characteristics of this species, which primarily occurs in high-altitude regions (approximately 500m to over 1,000m elevation). This study provides genome-wide insights into the genetic structure of Korean Sorbus species. Future studies incorporating comprehensive sampling of S. ulleungensis across Ulleung Island and S. commixta populations from other regions (Japan and Russia) will facilitate understanding of the evolutionary history and divergence patterns of these species.

This research was supported by Scientific Research Grants (KNA1-1-34-26-2) of the Korea National Arboretum.