Hedging at the rear edge: Intraspecific trait variability drives the trajectory of marginal populations in a widespread boreal tree species

Pelletier, Emmanuelle, Couture, Magali et de Lafontaine, Guillaume ORCID: https://orcid.org/0000-0001-6889-1733 (2023). Hedging at the rear edge: Intraspecific trait variability drives the trajectory of marginal populations in a widespread boreal tree species. Journal of Ecology, 111 (2). pp. 479-494.

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Résumé

Rear-edge populations at the warm margin of species distribution are small, isolated and face environmental conditions at the limit of species bioclimatic envelope. Intraspecific phenotypic variation contributing to the persistence of peripheral populations is expected to become increasingly important under future climate conditions to avoid local extirpation where range shifts lag behind climate change velocity.

We investigated the putative role of intraspecific phenotypic variation for the maintenance of rear-edge populations of fire-prone jack pine (Pinus banksiana), an obligate pyriscent boreal species. We assessed whether variation in cone serotiny is associated with the population trajectory of marginal stands located south of the boreal biome, in the temperate forest where natural wildfires are infrequent and unpredictable. To this end, we estimated stand-scale serotiny, minimal age and tree size structure in 26 jack pine stands from the rear edge (n = 17 sites) and the core (n = 9 sites) of the species' range in eastern Canada.

On average, rear-edge jack pine populations are less serotinous albeit more variably compared with range-core populations where serotiny is more uniformly high. Rear-edge stands are generally older and display reverse J-shape tree size structure indicative of a multi-aged demographic equilibrium, whereas range-core stands are younger and show a unimodal stand structure depicting a single ageing cohort generally lacking interfire recruitment. Eco-evolutionary dynamics shifts from a dependency on wildfires in range-core populations to stands that can regenerate and persist without recurrent fires at the rear edge, where stand-scale serotiny reaches values below 85%.

Synthesis. Unlike range-core populations, rear-edge jack pine populations can locally rely on a dual life-history strategy to ensure both steady recruitment during fire-free intervals and successful postfire regeneration. This capacity to cope with infrequent and unpredictable fire regime should increase the resilience and resistance of jack pine populations as global changes alter fire dynamics of the boreal forest. More generally, unique intraspecific phenotypic variation in rear-edge populations contributes to long-term species persistence in marginal environmental conditions that might scale up with global changes. The conservation of rear-edge populations and their genetic legacy appears crucial for the resilience of species. -- Keywords : bet-hedging ; eco-evolutionary dynamics ; fire regime ; local adaptation ; Pinus banksiana ; population trajectory ; rear edge ; serotiny.

Type de document :	Article
Validation par les pairs :	Oui
Information complémentaire :	Ceci est la version révisée par les pairs de l'article suivant : Pelletier, E., Couture, M. et de Lafontaine, G. (2023). Hedging at the rear edge: Intraspecific trait variability drives the trajectory of marginal populations in a widespread boreal tree species. Journal of Ecology, 111(2), 479-494., qui a été publié sous sa forme finale à l'adresse: https://doi.org/10.1111/1365-2745.14041 Cet article peut être utilisé à des fins non commerciales conformément aux conditions générales d'utilisation des versions auto-archivées de Wiley. Cet article ne peut être amélioré, enrichi ou transformé en une œuvre dérivée sans l'autorisation expresse de Wiley ou sans les droits statutaires prévus par la législation applicable. Les mentions de copyright ne doivent pas être supprimées, masquées ou modifiées. L'article doit être lié à la version d'enregistrement de Wiley sur Wiley Online Library et toute intégration, encadrement ou autre mise à disposition de l'article ou de ses pages par des tiers à partir de plateformes, services et sites web autres que Wiley Online Library est interdite.
Mots-clés :	Pin gris, Pinus banksiana, Cônes, Régénération (Botanique), Forêts, Incendies, Adaptation (Biologie), Phénotypes Taïgas, Sérotinisme, Répartition.
Version du document déposé :	Post-print (version corrigée et acceptée)
Départements et unités départementales :	Département de biologie, chimie et géographie > Biologie
Déposé par :	DIUQAR UQAR
Date de dépôt :	14 nov. 2023 15:51
Dernière modification :	22 nov. 2023 05:00
URI :	https://semaphore.uqar.ca/id/eprint/2648

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