Leaf size and shape show contrasting relationships with evolutionary lineages in Daphne blagayana Freyer

Brus, Robert (author), Fišer, Živa (author), Ballian, Dalibor (author), Jarni, Kristjan (author)

Phenotypic variation does not always correspond closely to genetic structure within species, particularly for morphological traits that are also influenced by environmental conditions. We examined whether leaf morphology in Daphne blagayana reflects previously identified phylogeographic structures and whether size- and shape-related traits differ in the hierarchical distribution of variation. Leaf morphometric analyses were performed on 3439 leaves collected from 596 shrubs in 21 populations covering the entire distribution range of the species. Ten leaf morphological traits were analysed using nested mixed-effects models, principal component analysis (PCA), MANOVA, Mantel tests and additional conservative mixed-effects models accounting for population-level structure. Leaf size-related traits showed stronger population-level differentiation and clearer geographic structuring, whereas shape-related traits exhibited higher within-shrub variation and weaker correspondence with phylogeographic structure. PCA and MANOVA revealed significant morphological differentiation among the three previously defined evolutionarily significant units (ESUs), although overlap among groups remained considerable. When population-level structure was taken into account, ESU effects were reduced but remained detectable for leaf length and selected shape-related traits. The northwestern ESU was characterized by larger and broader leaves, while differences between the central–southeastern and central ESUs were associated mainly with leaf shape traits. Mantel analysis revealed a weak but significant correlation between geographic and morphological distances among populations, indicating that geographic distance contributes to, but does not fully explain, morphological differentiation. The results show that leaf morphology in D. blagayana is associated with the previously identified phylogeographic structure of the species and that size- and shape-related traits differ markedly in their degree of geographic differentiation and hierarchical variation. However, because phylogeographic and geographic structure are spatially confounded in the present dataset, their individual effects on leaf morphology cannot be statistically separated. The study also highlights the importance of hierarchical sampling, appropriate statistical analyses, and cautious interpretation of genotype–phenotype correspondence in observational studies of intraspecific morphological variation.

• Language: English
• Keywords: leaf morphology, leaf morphometrics, phylogeographic structure, population differentiation, evolutionarily significant units, intraspecific variation
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: BF - Biotechnical Faculty
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: 18 str.
• Numbering: Vol. 17, iss. 8, art. 948
• PID: 20.500.12556/RUL-185592
• UDC: 581.45:582.685.8
• ISSN on article: 1999-4907
• DOI: 10.3390/f17080948
• COBISS.SI-ID: 287459075
• Publication date in RUL: 11.08.2026

Record is a part of a journal

• Title: Forests
• Shortened title: Forests
• Publisher: MDPI
• ISSN: 1999-4907
• COBISS.SI-ID: 3872166

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: morfologija lista, morfometrija lista, filogeografska struktura, diferenciacija populacij, evolucijsko pomembne enote, znotrajvrstna variabilnost

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P4-0059-2020
• Name: Gozd, gozdarstvo in obnovljivi gozdni viri