Jack pine of all trades: Decipheringintraspecific variability of a key adaptive trait at the rear edge of a widespread fire‐embracing North American conifer

Pelletier, Emmanuelle et de Lafontaine, Guillaume ORCID: https://orcid.org/0000-0001-6889-1733 (2023). Jack pine of all trades: Decipheringintraspecific variability of a key adaptive trait at the rear edge of a widespread fire‐embracing North American conifer. American Journal of Botany, 110 (2). e16111.

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Résumé

Premise
Understanding mechanisms fostering long-term persistence of marginal populations should provide key insights about species resilience facing climate change. Cone serotiny is a key adaptive trait in Pinus banksiana (jack pine), which shows phenotypic variation according to the fire regime. Compared to range-core populations within the fire-prone boreal forest, low and variable serotiny in rear-edge populations suggest local adaptation to uncommon and unpredictable wildfire regime. We assessed environmental/physiological factors that might modulate intraspecific variation in cone serotiny.

Methods
We experimentally subjected closed cones to incrementing temperatures, then tested seed germination to determine whether and how various ecological factors (cone age, branch height, tree size, tree age) are related to cone dehiscence and seed viability in jack pines from rear-edge and range-core populations in eastern Canada.

Results
Cones from rear-edge populations dehisce at a lower opening temperature, which increases with cone age. Cones from range-core stands open at a more constant, yet higher temperature. Cones from rear-edge stands take between 13 and 27 years to reach the level of serotiny achieved at the range core. At the rear edge, seed viability is steady (51%), whereas it decreases from 70% to 30% in 20 years at the range core.

Conclusions
We inferred the mechanisms of a bet-hedging strategy in rear-edge populations, which ensures steady recruitment during fire-free intervals and successful postfire regeneration. This capacity to cope with infrequent and unpredictable fire regime should increase the resilience of jack pine populations as global changes alter fire dynamics of the boreal forest. -- Keywords : bet‐hedging strategy ; boreal biome ; eco‐evolutionary dynamics ; fire disturbance ; intraspecific traitvariation ; marginal populations ; Pinaceae ; Pinus banksiana ; rear edge ; serotiny.

Type de document :	Article
Validation par les pairs :	Oui
Information complémentaire :	CC BY-NC
Mots-clés :	Pin gris ; Pinus banksiana ; Variabilité génétique ; Cônes ; Régénération (Botanique) ; Forêts ; Incendies ; Adaptation (Biologie) ; Phénotypes Taïgas ; Sérotinisme.
Version du document déposé :	Version officielle de l'éditeur
Départements et unités départementales :	Département de biologie, chimie et géographie > Biologie
Déposé par :	DIUQAR UQAR
Date de dépôt :	16 mars 2023 14:52
Dernière modification :	02 oct. 2023 17:23
URI :	https://semaphore.uqar.ca/id/eprint/2125

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