Genetic and ecological differentiation of Caragana jubata (Pall.) Poir

• Published in: Botanica Pacifica : journal of plant science and conservation
• Main Authors: Hantemirova, Elena V., Khoreva, Maria G., Bessonova, Varvara A.
• Format: Journal Article
• Language: English
• Published: 2024
• ISSN: 2226-4701; 2410-3713
• DOI: 10.17581/bp.2024.13204

Caragana jubata (Pall.) Poir. is a cold-tolerant mountain shrub and important medicinal species of Fabaceae family with a disjunctive pan-Asian range. Sequences of the atpH-atpI and trnL-trnF intergenic spacers of chloroplast DNA and of the internal transcribed spacer region, ITS-1, of the nuclear ribosomal DNA were used to investigate the intraspecific evolution and phylogeography of this species. Eleven cpDNA haplotypes were identified. The population subdivision is very high (GST = 0.743, NST = 0.943), suggesting a distinct phylogeographic structure (NST > GST, P < 0.001). Phylogenetic analyses of the eleven haplotypes were clustered into four clades, consistent with their respective distributions in four separate regions: Tibet, Tien Shan, Buryatia and Magadan Region. This pronounced phylogeographic gap is also confirmed by nrITS data, however, there is some mixture of genotypes in the Magadan and Buryat populations. Genetic evidence suggests that the center of origin of C. jubata was Tibet and adjacent mountain systems, from where the species spread westwards along continuous mountain chains towards the Tien Shan and northeastwards to the coast of the Sea of Okhotsk and further northwards to Arctic. Divergence of Tien Shan populations of C. jubata may have been caused by climate change in the Pleistocene associated with increased aridity and expansion of deserts, while subsequent climate-induced cycles of range contraction/expansion increased geographic isolation and fragmentation of more northern populations. Marginal northern populations now occupy sites with the most favourable environmental conditions. Special attention is paid to the Okhotsk populations of this species preserved in Magadan Region.