The establishment history of alpine Leontopodium japonicum (Asteraceae) resembles that of warm-temperate plants on the Korean Peninsula

Abstract

Historical migration patterns of boreal and alpine plants have had a narrow focus on the Korean Peninsula, generally being characterized as southern relics from northern-sourced populations. Here, we present another hypothesis for the pattern associated with Korean alpine species. A genetic analysis was conducted with Leontopodium japonicum Miq., which grows in high mountain ranges with a disjunct distribution across Korea, China, and Japan. We inferred its phylogeography using sequences of nuclear (ITS) and chloroplast DNA (trnL–F, rps16, and rpl16) for 11 populations from Korea and adjacent regions. Our molecular data (SAMOVA and network analyses) revealed a distinct genetic isolation of Korean populations with the highest genetic differentiation (Korea vs. China and Japan). By comparison, a nonsignificant level of differentiation, but a high degree of genetic diversity, was detected between Chinese and Japanese populations, resembling that of warm-temperate species. These findings demonstrate that, rather than migrating southward from more northern latitudes, current populations in Korea are distributed due to colonization via East China Sea land bridges, similar to movement by warm-temperate species. Furthermore, geographical isolation because of an oceanic barrier has led to allopatric speciation for Korean populations. This specific scenario for L. japonicum is a meaningful example that will enhance our understanding of the history of plants growing in alpine (or subalpine) zones of Korea.