Phylogeographic analyses of poplar revealed potential glacial refugia and allopatric divergence in southwest China

Abstract

The distribution pattern and genetic structure of plant species have been profoundly influenced by climate oscillations. Phylogeographic analyses have been numerously conducted in biodiversity hotspot regions and some general conclusions have been documented. However, other regions have received less attentions and these places may serve as potential glacial refugia for plant species to survive the Quaternary glaciation. Here, we used six nuclear and three cpDNA markers to estimate the phylogeographic pattern of Populus davidiana, a widespread species distributed in southwest China. As a widely distributed species in southwest China, the nucleotide diversity of P. davidiana was relatively high (N_a = 6.28, H_O = 0.534, and H_E = 0.658). Genetic differentiation (F_ST) between the two main distribution regions, Yunnan and Guizhou provinces, was 0.21221. According to the composition of chloroplast haplotypes and the result of structure in these populations, we clearly distinguished two distantly sublineages corresponding to two distribution regions. Results of the Mantel test showed that there was a significant correlation between genetic distance and geographical distance (R² = 0.8252, p<.05). The topographically heterogeneous regions and the low dispersal ability of seed and pollen may lead to high genetic differentiation between these two regions. A potential glacial refugia for P. davidiana located in adjacent regions to the Hengduan range was revealed and allopatric divergence in separated glacial refugia may directly lead to the present phylogeographic pattern of this species.

Keywords:

• Molecular variation
• quaternary glaciations
• temperate forest
• glacial refugia

Acknowledgements

The authors thank Li Ang for her suggestion on data analysis.

Disclosure statement

All authors have acquired any permits needed for planning and executing the study reported in the paper.

Additional information

Funding

Financial support for this research was provided by the Open Fund of Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University [Grant No. ESP2004], the Open Fund of MOE Key Laboratory of Biodiversity and Ecology Engineering, Beijing Normal University [Grant No. K202001] and the Fundamental Research Funds of China West Normal University [Grant No. 19E044].