Genomic insights into the local adaptation of spontaneous olive trees in the Mediterranean Basin highlight the need for conservation planning in the face of global change
Lison Zunino, Gautier Sarah, Lorenzo Rocchetti, Bénédicte Rhoné, Alexandre Soriano, Gaëtan Droc, Pierre Mournet, Ahmed El Bakkali, Evelyne Costes, Bouchaib Khadari, Philippe CubrySocietal Impact Statement
The Mediterranean Basin, a major biodiversity hotspot, is highly vulnerable to climate and global changes. Wild olive trees form an essential part of this landscape and hold strong ecological, cultural and socio‐economic significance. By examining how these trees responded to past climatic conditions, this study shows adaptation of olive trees to local conditions of temperature and precipitation. Gene flow from cultivated olive into wild populations does not appear to reduce this adaptive potential. These findings provide valuable guidance for conservation planning and restoration efforts, supporting the protection of resilient olive populations and Mediterranean ecosystems under ongoing climate change.
Le bassin méditerranéen, une zone de forte biodiversité, est particulièrement vulnérable aux changements globaux. Les oliviers sauvages constituent une partie essentielle de ce paysage et possèdent une grande importance écologique, culturelle et socio‐économique. En examinant comment ces arbres ont réagi aux conditions climatiques passées, cette étude met en évidence l'adaptation des oliviers aux conditions locales de température et de précipitations. Le flux de gènes provenant des oliviers cultivés vers les populations sauvages ne semble pas réduire ce potentiel d'adaptation. Ces résultats fournissent des orientations précieuses pour la planification de la conservation et les efforts de restauration, en soutenant la protection des populations d'oliviers résilientes et des écosystèmes méditerranéens face au changement climatique en cours.
Summary
Rapid environmental changes threaten global biodiversity, with the Mediterranean Basin (MB) being highly vulnerable due to faster warming rates. In the western MB, spontaneously occurring populations of
We analysed genome sequencing data from spontaneously occurring populations and cultivated olives. Selective sweep detection and genotype–environment association (GEA) approaches were applied to wild populations to detect genomic regions associated with climate variations. Our results revealed genomic signatures of adaptation in wild olives, mainly related to temperature and precipitation during the coldest quarter. Notably, numerous polymorphic candidate SNPs detected in the wild compartment were also found polymorphic in admixed individuals but were invariant in cultivated individuals, suggesting that introgression might conserve much of the wild adaptive potential. The broadening of standing genetic variation resulting from hybridization could further accelerate adaptation to novel or shifting environments. In conclusion, we provide evidence that western genuine wild olives are locally adapted and that admixed populations maintain key adaptive variants. It also highlights the risk of future (mal)adaptation of natural populations and reinforces the need for spontaneously occurring olives conservation.