Natural selection preserves trans-specific chloroplast diversity in a Mediterranean evergreen oak
Cork oak (Quercus suber) is an ecologically and economically important Western Mediterranean tree species in severe risk of decline due to aggravated tree mortality and lack of natural regeneration. In Q. suber, two distinct chloroplast lineages, one of them of trans-specific origin, occur in sympatry in the western half of its species distribution. We hypothesize that selection may drive the maintenance of the two lineages and investigate this hypothesis by sequencing chloroplast genomes of 259 Q. suber samples across 24 locations. Protein-coding chloroplast genes were scanned for selection signal using different codon-based methods. Selection signal was found at different sites and genes, and polymorphism in selected sites was shown to segregate between the two chloroplast lineages. We postulate that trans-specific chloroplast diversity in Q. suber is preserved by balancing selection, rather than resulting exclusively from ongoing introgression. These results correspond to an unusual case of balancing selection on whole plastid genomes in a long-lived woody plant species and have implications on conservation and management practices for Q. suber, which may benefit from taking into account genetic variation in plastid genomes as a possible source of increased adaptive potential for the species.
Authors
- Sandro Dettori (ORCID: https://orcid.org/0000-0002-9817-7714)
- Pär K. Ingvarsson (ORCID: https://orcid.org/0000-0001-9225-7521)
- Cristina Branquinho (ORCID: https://orcid.org/0000-0001-8294-7924)
- Touhami Rzigui
- Dora Batista (ORCID: https://orcid.org/0000-0003-4031-8999)
- Ana Cristina Coelho (ORCID: https://orcid.org/0000-0002-2919-5468)
- Luigi Forte (ORCID: https://orcid.org/0000-0001-8168-7999)
- Adriana Príncipe (ORCID: https://orcid.org/0000-0002-5147-835X)
- Saverio Sciandrello
- Pedro Rocha (ORCID: https://orcid.org/0000-0002-2871-5070)
- Gianpietro Giusso del Galdo (ORCID: https://orcid.org/0000-0003-4719-3711)
- Mathieu Vanhove (ORCID: https://orcid.org/0000-0002-6090-8796)
- Bouchra Belkadi (ORCID: https://orcid.org/0000-0002-1709-3042)
- André Henriques (ORCID: https://orcid.org/0000-0003-2800-046X)
- Mohamed Ouadji
- L. Lacey Knowles
- Marcello Cillara
- Paulo De Sousa (ORCID: https://orcid.org/0000-0002-2333-6493)
- Florian Galinat
- Mariana Bray Viegas
- Viviana Cavallaro (ORCID: https://orcid.org/0000-0002-9403-2083)
- Octávio S. Paulo (ORCID: https://orcid.org/0000-0001-5408-5212)
- Filipe Sousa (ORCID: https://orcid.org/0000-0003-4681-8951)
- Yacine Torche
- Augusta Costa (ORCID: https://orcid.org/0000-0002-0400-8523)
- João Bilro (ORCID: https://orcid.org/0009-0009-5582-5978)
- Domenico Saulle
- Aoujdad Jalila
- Davide Galhofa
Institutions
- Instituto de Engenharia de Sistemas e Computadores Investigação e Desenvolvimento (PT)
- Mohammed V University (MA)
- Center for Disease Dynamics, Economics & Policy (US)
- Harvard University (US)
- University of Lisbon (PT)
- University of Sassari (IT)
- University of Michigan (US)
- Luther University (KR)
- Swedish University of Agricultural Sciences (SE)
- University of Catania (IT)
- Sustainability Institute (ZA)
- Secretaria Regional do Ambiente e Recursos Naturais (PT)
- Instituto Nacional de Investigação Agrária e Veterinária (PT)
- Evolutionary Genomics (United States) (US)
- Centre National de la Propriété Forestière (FR)
- National Research Institute of Rural Engineering, Water and Forests (TN)
- Forest Research (GB)
- Ecologie et Ecophysiologie Forestières (FR)
- Centre Universitaire de Mila (DZ)
- Hospital da Restauração (BR)
- University of Bari Aldo Moro (IT)
- Martin Luther University Halle-Wittenberg (DE)
- University of Algarve (PT)
- Universidade Nova de Lisboa (PT)
Publication Details
- Journal
- Journal of Evolutionary Biology
- Published
- 2025-10-15
- DOI
- https://doi.org/10.1093/jeb/voaf125
- Primary Topic
- Genomics and Phylogenetic Studies
- Type
- article
- Field-Weighted Citation Impact
- 0.00