Lack of phylogeographic pattern in populations of Dacrycarpus imbricatus (Podocarpaceae) from mainland China and Hainan island

Historical climate fluctuations and geological events can affect the distribution range and demographic history of plant populations. Dacrycarpus imbricatus is a member of the Podocarpaceae family, mainly distributed in mainland China and Hainan Island in China. It thus provides a framework for unraveling the specific impact of Qiongzhou Strait on the phylogeographic pattern of the species. In this study, seven populations were sampled throughout its distribution range in China. Based on the variation of chloroplast DNA (cpDNA), the trnF-L noncoding region sequence, phylogeographic pattern, population genetic structure, population history, and ecological niche model of D. imbricatus were calculated. The haplotype diversity was 0.719, and the nucleotide diversity was 1.630 x 10(-3). Moreover, the results did not show a significant phylogeographic pattern between the island and the mainland populations. Qiongzhou Strait did not serve as a geographic barrier in genetic variation. The haplotype network diagram and a mismatch distribution indicated that the D. imbricatus population had experienced a population expansion event. Ecological niche modeling suggested the distribution range of D. imbricatus population has gradually expanded northward. These results might contribute to establishing ecological reserves and understanding the impact of Qiongzhou Strait on plants in coastal areas of East Asia.