Rear‐edge, low‐diversity, and haplotypic uniformity in cold‐adapted Bupleurum euphorbioides interglacial refugia populations

• Published in: Ecology and evolution 2020-10, Vol.10 (19), p.10449-10462
• Main Authors: Cho, Won‐Bum, So, Soonku, Han, Eun‐Kyeong, Myeong, Hyeon‐Ho, Park, Jong‐Soo, Hwang, Seung‐Hyun, Kim, Joo‐Hwan, Lee, Jung‐Hyun
• Format: Article
• Language: English
• Subjects: Adaptation; Baekdudaegan; Bupleurum; Bupleurum euphorbioides; Chloroplast DNA; Chloroplasts; Climate change; Cold; cold‐adapted; Congeners; Contraction; Deoxyribonucleic acid; DNA; Ecological niches; Empirical analysis; Endangered & extinct species; Environmental changes; Flowers & plants; Gene sequencing; Genetic diversity; Genetic markers; Genetic structure; Glacial periods; Glaciers; Habitats; Interglacial periods; interglacial refugia; Life history; Microsatellites; Migratory species; Niches; Nucleotide sequence; Original Research; Population; Population genetics; Populations; Quaternary; rear‐edge; Refugia; Seeds; Species; Species diversity
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.6700

The high genetic diversity of rear‐edge refugia populations is predicted to have resulted from species repeatedly migrating to low latitudes during glacial periods over the course of Quaternary climate change. However, several recent empirical studies of cold‐tolerant plants revealed the opposite pattern. We investigated whether current habitats of the cold‐adapted and range‐restricted Bupleurum euphorbioides in the Baekdudaegan, South Korea, and North Korea could be interglacial refugia, and documented how their rear‐edge populations differ genetically from those of typical temperate species. Phylogeographic analysis and ecological niche modeling (ENM) were used. The genetic structure was analyzed using microsatellite markers and chloroplast DNA sequences. The congener B. longiradiatum was included as a typical temperate plant species. Despite having almost identical life history traits, these congeneric species exhibited contrasting patterns of genetic diversity. ENM revealed an apparent maximum range contraction during the last interglacial. In contrast, its range expanded northward to the Russian Far East (Primorsky) during the Last Glacial Maximum. Thus, we hypothesize that B. euphorbioides retreated to its current refugia during interglacial periods. Unlike populations in the central region, the rear‐edge populations were genetically impoverished and uniform, both within populations and in pooled regional populations. The rear‐edge B. euphorbioides survived at least one past interglacial, contributing to the species’ genetic diversity. We believe that such genetic variation in the cold‐adapted B. euphorbioides gives the species the necessary adaptations to survive an upcoming favorable environment (the next glacial), unless there is artificial environmental change. The study shows a pattern that contrasts with the changes in the distribution range that typical temperate plants experienced in the course of Quaternary climate change. ENM revealed an apparent maximum range contraction during the last interglacial. In contrast, its range expanded northward to Russian Far East (Primorsky) during the Last Glacial Maximum. The rear‐edge populations were genetically impoverished and uniform, both within populations and in pooled regional populations. We believe that such genetic variation in the cold‐adapted Bupleurum euphorbioides gives it the necessary adaptations that will enable it to survive an upcoming favorable environment (the next glacial), unless t