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ORIGINAL RESEARCH article

Front. Plant Sci.
Sec. Plant Systematics and Evolution
Volume 16 - 2025 | doi: 10.3389/fpls.2025.1518122

Species Delimitation in the Populus laurifolia Complex (Salicaceae) Based on Phylogenetic and Morphometric Evidence

Provisionally accepted
Wei Xueya Wei Xueya Cui Xingyong Cui Xingyong *Yuan Fulin Yuan Fulin *Zhou Kerou Zhou Kerou *Zhou Liwei Zhou Liwei *Zhao Changli Zhao Changli *Guo Shaoyu Guo Shaoyu *Ce Shang Ce Shang *Zhang Zhixiang Zhang Zhixiang *
  • Beijing Forestry University, Beijing, China

The final, formatted version of the article will be published soon.

    Due to significant morphological differences and extensive interspecific hybridization, there are numerous species complexes with taxonomic challenges in the genus Populus. Integrative taxonomy, which combines evidence of morphology, molecular phylogeny, niche differentiation, and reproductive isolation, provides the most effective approaches for species delimitation.The Populus laurifolia complex, which belongs to Populus subg. Tacamahaca (Salicaceae), is distributed in the Altai Mountains and Tianshan Mountains. This complex exhibits morphological variability, making species delimitation challenging. Due to limited sampling and systematic studies, its taxonomy has remained unresolved. In this study, 337 specimens, along with online digital samples representing nearly all wild populations, were collected. Morphological analyses were performed to evaluate key traits and clarify species boundaries. Phylogenetic relationships were reconstructed using concatenation and coalescent methods based on 566,375 nuclear single nucleotide polymorphisms (SNPs). Ecological niche differentiation was assessed, and ABBA-BABA analysis was used to examine interspecific hybridization. The results revealed that this complex, based on a series of significant character states, could be morphologically distinguished into three species, P. laurifolia (P. pilosa considered a synonym of P. laurifolia), P. talassica, and P. pamirica, which also correspond to three wellsupported clades in the phylogenetic trees. Populus pamirica exhibits some degree of ecological niche differentiation from P. talassica and P. laurifolia, whereas the latter two show minimal differentiation. Gene flow within the complex remains limited. This research underscores the importance of integrating multiple lines of evidence in the classification of Populus, providing a framework for future taxonomic studies.

    Keywords: Populus laurifolia, species complex, phylogenomics, species delimitation, Integrative taxonomy

    Received: 28 Oct 2024; Accepted: 09 Jan 2025.

    Copyright: © 2025 Xueya, Xingyong, Fulin, Kerou, Liwei, Changli, Shaoyu, Shang and Zhixiang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Cui Xingyong, Beijing Forestry University, Beijing, China
    Yuan Fulin, Beijing Forestry University, Beijing, China
    Zhou Kerou, Beijing Forestry University, Beijing, China
    Zhou Liwei, Beijing Forestry University, Beijing, China
    Zhao Changli, Beijing Forestry University, Beijing, China
    Guo Shaoyu, Beijing Forestry University, Beijing, China
    Ce Shang, Beijing Forestry University, Beijing, China
    Zhang Zhixiang, Beijing Forestry University, Beijing, China

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