Species delimitation in the Populus laurifolia complex (Salicaceae) based on phylogenetic and morphometric evidence

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 isola...

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Main Authors: Xueya Wei, Xingyong Cui, Fulin Yuan, Kerou Zhou, Liwei Zhou, Changli Zhao, Shaoyu Guo, Ce Shang, Zhixiang Zhang
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-02-01
Series:Frontiers in Plant Science
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Online Access:https://www.frontiersin.org/articles/10.3389/fpls.2025.1518122/full
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author Xueya Wei
Xingyong Cui
Fulin Yuan
Kerou Zhou
Liwei Zhou
Changli Zhao
Shaoyu Guo
Ce Shang
Zhixiang Zhang
author_facet Xueya Wei
Xingyong Cui
Fulin Yuan
Kerou Zhou
Liwei Zhou
Changli Zhao
Shaoyu Guo
Ce Shang
Zhixiang Zhang
author_sort Xueya Wei
collection DOAJ
description 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 (Populus pilosa considered a synonym of P. laurifolia), Populus talassica, and Populus pamirica—which also correspond to three well-supported clades in the phylogenetic trees. P. 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.
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spelling doaj-art-e8fe0727e4434d868a803f4d3e3696a72025-02-06T07:09:32ZengFrontiers Media S.A.Frontiers in Plant Science1664-462X2025-02-011610.3389/fpls.2025.15181221518122Species delimitation in the Populus laurifolia complex (Salicaceae) based on phylogenetic and morphometric evidenceXueya WeiXingyong CuiFulin YuanKerou ZhouLiwei ZhouChangli ZhaoShaoyu GuoCe ShangZhixiang ZhangDue 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 (Populus pilosa considered a synonym of P. laurifolia), Populus talassica, and Populus pamirica—which also correspond to three well-supported clades in the phylogenetic trees. P. 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.https://www.frontiersin.org/articles/10.3389/fpls.2025.1518122/fullPopulus laurifoliaspecies complexphylogenomicsspecies delimitationintegrative taxonomy
spellingShingle Xueya Wei
Xingyong Cui
Fulin Yuan
Kerou Zhou
Liwei Zhou
Changli Zhao
Shaoyu Guo
Ce Shang
Zhixiang Zhang
Species delimitation in the Populus laurifolia complex (Salicaceae) based on phylogenetic and morphometric evidence
Frontiers in Plant Science
Populus laurifolia
species complex
phylogenomics
species delimitation
integrative taxonomy
title Species delimitation in the Populus laurifolia complex (Salicaceae) based on phylogenetic and morphometric evidence
title_full Species delimitation in the Populus laurifolia complex (Salicaceae) based on phylogenetic and morphometric evidence
title_fullStr Species delimitation in the Populus laurifolia complex (Salicaceae) based on phylogenetic and morphometric evidence
title_full_unstemmed Species delimitation in the Populus laurifolia complex (Salicaceae) based on phylogenetic and morphometric evidence
title_short Species delimitation in the Populus laurifolia complex (Salicaceae) based on phylogenetic and morphometric evidence
title_sort species delimitation in the populus laurifolia complex salicaceae based on phylogenetic and morphometric evidence
topic Populus laurifolia
species complex
phylogenomics
species delimitation
integrative taxonomy
url https://www.frontiersin.org/articles/10.3389/fpls.2025.1518122/full
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