A Phylogeographic Study of Sassafras tzumu in China Based on Nuclear Microsatellite and Chloroplast DNA Sequences

Sassafras tzumu, an important tree species in subtropical forests of China, provides a valuable model for understanding regional biodiversity patterns and informing conservation strategies. Here, we integrated nuclear microsatellites (nSSRs), chloroplast DNA (cpDNA) sequences, and ecological niche modeling (ENM) to investigate 29 populations spanning the species’ entire natural range. nSSR analyses revealed a moderate level of genetic diversity (mean H E = 0.308), and analysis of molecular variance showed that 33% of the total genetic variation occurred among populations ( F ST = 0.333), indicating substantial population differentiation. Bayesian clustering, principal coordinate analysis, and phylogenetic reconstruction consistently supported two major genetic lineages: Lineage I from central and southeastern China and Lineage II from southwestern China. Their geographic boundary closely corresponded to the Daba Mountains–Xuefeng Mountains topographic barrier. Six cpDNA haplotypes (H1–H6) were identified, and both haplotype network and phylogenetic analyses supported two major clades largely congruent with the nSSR-based lineage pattern. A significant phylogeographic structure was detected ( N ST > G ST, P < 0.05). Divergence time estimation suggested that the split between the two lineages began in the Miocene (ca. 9.49 Mya), whereas major haplotype diversification occurred during the Pleistocene. Mismatch distribution and neutrality tests indicated historical population expansion. Ecological niche modeling indicated that the suitable range of S. tzumu during the Last Glacial Maximum was markedly reduced relative to the present, and that areas of high habitat suitability overlapped closely with several genetically inferred glacial refugia, including the Daba, Dabie, Wuling, and Wuyi Mountains, supporting a multiple-refugia scenario. Together, these results suggest that the current pattern of low diversity yet high differentiation in S. tzumu reflects the combined effects of Miocene geological events, Quaternary climatic oscillations, and strong contemporary geographic isolation, and provide a scientific basis for lineage-based conservation and climate-adaptive management. Information & Authors Information Version history Copyright This work is licensed under a Non Exclusive No Reuse License.

Authors Metrics & Citations Metrics Article Usage 135views 71downloads Citations Download citation Yahong Wang, Qixun Chen, Ying Wang, et al. A Phylogeographic Study of Sassafras tzumu in China Based on Nuclear Microsatellite and Chloroplast DNA Sequences. Authorea. 26 March 2026. DOI: https://doi.org/10.22541/au.177449976.64725443/v1 DOI: https://doi.org/10.22541/au.177449976.64725443/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu.