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Backgroundfecundity and viability selections on phenological traits are difficult to distinguish in plants, where vegetative and reproductive phenologies are closely synchronized. Moreover, interference with sexual selection may arise from assortative mating (the positive correlation between mates for flowering time). This study aims at disentangling these components of selection on spring phenology in European beech.Methodsthe timing of budburst (TBB) was surveyed in 147 and 192 adult trees in two natural populations at low and high elevation respectively along an altitudinal gradient. Male and female individual fecundities were estimated using paternity and parentage analyses of 1414 seeds and 473 seedlings, which also allowed mating networks to be inferred. Morever, TBB and growth was surveyed in 1552 and 1709 seedlings originating from the same populations and planted in a common garden.Resultsassortative mating occurred only at low elevation, where spring phenology was also more spread out. Phenological mismatch reduced male but not female fecundities at both plots, indicating sexual selection to maximize mating opportunities. At high elevation, directional fecundity selection for earlier TBB occurred both through male and female fecundities. At low elevation, directional fecundity selection for earlier spring phenology was mitigated by a positive association between TBB and fecundity in the smaller trees. In the common garden, early budburst was associated to higher seedling growth.DiscussionThis study showed that sexual selection arising from assortative mating could drive stabilizing selection on TBB through the male function, while selection through female fecundity predominantly selects for earlier TBB. This intertwining of sexual and fecundity selection calls for an integrative approach to predict the evolution of spring phenology under changing climate.

When environmental conditions differ both within and among populations, multiscale adaptation results from processes at both scales and interference across scales. We hypothesize that within-population environmental heterogeneity influences the chance of success of migration events, both within and among populations, and maintains within-population adaptive differentiation. We used a simulation approach to analyse the joint effects of environmental heterogeneity patterns, selection intensity and number of QTL controlling a selected trait on local adaptation in a hierarchical metapopulation design. We show the general effects of within-population environmental heterogeneity: (i) it increases occupancy rate at the margins of distribution ranges, under extreme environments and high levels of selection; (ii) it increases the adaptation lag in all environments; (iii) it impacts the genetic variance in each environment, depending on the ratio of within- to between-populations environmental heterogeneity; (iv) it reduces the selection-induced erosion of adaptive gene diversity. Most often, the smaller the number of QTL involved, the stronger are these effects. We also show that both within- and between-populations phenotypic differentiation (Q

International audience; Within-population variation in individual tree growth and response to climate has an impact on forest dynamics, resilience and adaptation to environmental change.Combining dendrochronological analyses with a process-based ecophysiological model simulating drought stress at the stand scale, we studied the phenotypic variation of two growth-related traits within 22 pure stands of five contrasted tree species sampled in the RENECOFOR network over a wide range of ecological conditions. First, we computed the annual stress level from soil, climate and stand inventory data. Second, we computed individual sensitivity as the quantitative growth response to drought stress level and individual vigor as the capacity to grow in favorable years relative to an average stand-level growth model. We analyzed within-population variation and covariation of individual vigor and sensitivity, their temporal changes during stand development, as well as the effect of environmental conditions on population-level means, variances and correlation.Our results show that within-population variances in sensitivity and vigor exceed the between-population variances for all species. The populations located in more stressful environments, i.e., low summer precipitation and extractable soil water, showed lower mean and variance of sensitivity, suggesting possible multiscale adaptation at the population level and within populations. None of the environmental factors considered had an effect on the average population vigor or on the within-population variance of vigor. We found a general positive correlation between individual growth sensitivity and vigor in 17 out of 22 populations, potentially revealing a growth performance trade-off. The correlation was more pronounced in low extractable soil water environments, which may be related to a need for stressful conditions to reveal the trade-off or be the consequence of adaptive processes, i.e., acclimation and selection.If high within-population stand phenotypic variation in growth traits contributes to the resilience and adaptive capacity of forests to climate change, a trade-off could represent a constraint on selection. We provide genetic and environmental arguments supporting the hypothesis of a trade-off, then we highlight the importance of integrating it into the management process, especially during selective thinning, to avoid indirectly increasing population sensitivity by selecting the most vigorous trees.

19 Pág., Microgeographical adaptation occurs when the effects of directional selection persist despite gene flow. Traits and genetic loci under selection can then show adaptive divergence, against the backdrop of little differentiation at other traits or loci. How common such events are and how strong the selection is that underlies them remain open questions. Here, we discovered and analysed microgeographical patterns of genomic divergence in four European and Mediterranean conifers with widely differing life-history traits and ecological requirements (Abies alba MIll., Cedrus atlantica [Endl.] Manetti, Pinus halepensis Mill. and Pinus pinaster Aiton) by screening pairs from geographically close forest stands sampled along steep ecological gradients. We inferred patterns of genomic divergence by applying a combination of divergence outlier detection methods, demographic modelling, Approximate Bayesian Computation inferences and genomic annotation to genomic data. Surprisingly for such small geographical scales, we showed that selection is strong in all species but generally affects different loci in each. A clear signature of selection was systematically detected on a fraction of the genome, of the order of 0.1%-1% of the loci depending on the species. The novel modelling method we designed for estimating selection coefficients showed that the microgeographical selection coefficient scaled by population size (Ns) was 2-30. Our results convincingly suggest that selection maintains within-population diversity at microgeographical scales in spatially heterogeneous environments. Such genetic diversity is likely to be a major reservoir of adaptive potential, helping populations to adapt under fluctuating environmental conditions., Agence Nationale de la Recherche, Grant/ Award Number: FLAG project (ANR-12- ADAP-0007-01); European Commission, Grant/Award Number: TOPWOOD project (MSCA-RISE-2014-645654- TOPWOOD) and grant agreement No. 676876 (GenTree); Ministère de l'Écologie, du Développement Durable et de l'Énergie, Grant/Award Number: GRAAL project (10-MCGOT-GICC-8-CVS-139)

High genetic variation and extensive gene flow may help forest trees with adapting to ongoing climate change, yet the genetic bases underlying their adaptive potential remain largely unknown. We investigated range-wide patterns of potentially adaptive genetic variation in 64 populations of European beech (Fagus sylvatica L.) using 270 SNPs from 139 candidate genes involved either in phenology or in stress responses. We inferred neutral genetic structure and processes (drift and gene flow) and performed differentiation outlier analyses and gene-environment association (GEA) analyses to detect signatures of divergent selection.Beech range-wide genetic structure was consistent with the species’ previously identified postglacial expansion scenario and recolonization routes. Populations showed high diversity and low differentiation along the major expansion routes. A total of 52 loci were found to be putatively under selection and 15 of them turned up in multiple GEA analyses. Temperature and precipitation related variables were equally represented in significant genotype-climate associations. Signatures of divergent selection were detected in the same proportion for stress response and phenology-related genes. The range-wide adaptive genetic structure of beech appears highly integrated, suggesting a balanced contribution of phenology and stress-related genes to local adaptation, and of temperature and precipitation regimes to genetic clines. Our results imply a best-case scenario for the maintenance of high genetic diversity during range shifts in beech (and putatively other forest trees) with a combination of gene flow maintaining within-population neutral diversity and selection maintaining between-population adaptive differentiation.

International audience; Plant trait variability, emerging from eco-evolutionary dynamics that range from alleles to macroecological scales, is one of the most elusive, but possibly most consequential, aspects of biodiversity. Plasticity, epigenetics, and genetic diversity are major determinants of how plants will respond to climate change, yet these processes are rarely represented in current vegetation models. Here, we provide an overview of the challenges associated with understanding the causes and consequences of plant trait variability, and review current developments to include plasticity and evolutionary mechanisms in vegetation models. We also present a roadmap of research priorities to develop a next generation of vegetation models with flexible traits. Including trait variability in vegetation models is necessary to better represent biosphere responses to global change.

International audience; Key Message: We provide phenotypic and genotypic data for a progeny trial of 5813 European beech seedlings, originating from 60 open-pollinated families collected at three altitudes (1020 m; 1140 m, 1340 m) on Mont Ventoux (44° 11′ N; 17° 5′ E).Background: Considering the patterns of adaptive traits’ genetic divergence and local adaptation displayed by many tree species at large spatial scale, forest tree populations are usually assumed to have a high evolutionary potential (Alberto et al. 2013). However, there is still limited evidence of the level of genetic variation available within population at key functional traits involved in response to climate. Moreover, we also need to investigate the abilities of tree populations to adapt to local variation of their environment (i.e., microgeographic adaptation, Richardson et al. 2014).Abstract: This data paper extensively describes a valuable quantitative genetic experiment designed to address these issues in the European beech (Fagus sylvatica L.), a major tree species in Europe. Sixty beech maternal progenies were collected in three plots along an elevation gradient and grown in a common garden under two contrasted experimental conditions (water stress/no water stress), to assess how the variation at twelve adaptive traits partitioned within and among families, plots, and experimental contrasts. Moreover, we genotyped a subset of offspring and all the potentially reproductive adults in the three plots at 13 microsatellite markers to infer paternal relationships and to estimate average relatedness within and between maternal families and genetic divergence among plots.

Background and Aims Abiotic and biotic stresses related to climate change have been associated with increased crown defoliation, decreased growth and a higher risk of mortality in many forest tree species, but the impact of stresses on tree reproduction and forest regeneration remains understudied. At the dry, warm margin of species distributions, flowering, pollination and seed maturation are expected to be affected by drought, late frost and other stresses, eventually resulting in reproduction failure. Moreover, inter-individual variation in reproductive performance versus other performance traits (growth, survival) could have important consequences for population dynamics. This study investigated the relationships among individual crown defoliation, growth and reproduction in a drought-prone population of European beech, Fagus sylvatica. Methods We used a spatially explicit mating model and marker-based parentage analyses to estimate effective female and male fecundities of 432 reproductive trees, which were also monitored for basal area increment and crown defoliation over 9 years. Key Results Female and male fecundities varied markedly between individuals, more than did growth. Both female fecundity and growth decreased with increasing crown defoliation and competition, and increased with size. Moreover, the negative effect of defoliation on female fecundity was size-dependent, with a slower decline in female fecundity with increasing defoliation for the large individuals. Finally, a trade-off between growth and female fecundity was observed in response to defoliation: some large trees maintained significant female fecundity at the expense of reduced growth in response to defoliation, while some other defoliated trees maintained high growth at the expense of reduced female fecundity. Conclusions Our results suggest that, while decreasing their growth, some large defoliated trees still contribute to reproduction through seed production and pollination. This non-coordinated decline of growth and fecundity at individual level in response to stress may compromise the evolution of stress-resistance traits at population level, and increase forest tree vulnerability.

We dedicate this manuscript to I.O. who passed away before the completion of this study, which she initiated. She inspired and is still inspiring our research in many ways.; International audience; Sexual dimorphism in plants may emerge as a result of sex-specific selection on traits enhancing access to nutritive resources and/or to sexual partners. Here we investigated sex-specific differences in selection of sexually dimorphic traits and in the spatial distribution of effective fecundity (our fitness proxy) in a highly dimorphic dioecious wind-pollinated shrub, Leucadendron rubrum. In particular, we tested for the effect of density on male and female effective fecundity. We used spatial and genotypic data of parent and offspring cohorts to jointly estimate individual male and female effective fecundity on the one hand and pollen and seed dispersal kernels on the other hand. This methodology was adapted to the case of dioecious species. Explicitly modelling dispersal avoids the confounding effects of heterogeneous spatial distribution of mates and sampled seedlings on the estimation of effective fecundity. We also estimated selection gradients on plant traits while modelling sex-specific spatial autocorrelation in fecundity. Males exhibited spatial autocorrelation in effective fecundity at a smaller scale than females. A higher local density of plants was associated with lower effective fecundity in males but was not related to female effective fecundity. These results suggest sex-specific sensitivities to environmental heterogeneity in L. rubrum. Despite these sexual differences, we found directional selection for wider canopies and smaller leaves in both sexes, and no sexually antagonistic selection on strongly dimorphic traits in L. rubrum. Many empirical studies in animals similarly failed to detect sexually antagonistic selection in species expressing strong sexual dimorphism, and we discuss reasons explaining this common pattern.

1AbstractA trade-off between growth and fecundity, reflecting the inability of simultaneously investing in both functions when resources are limited, is a fundamental feature of life history theory. This particular trade-off is the result of evolutionary and environmental constrains shaping reproductive and growth traits, but it remains difficult to pinpoint in natural populations of long-lived plants. We developed a hierarchical Bayesian model to estimate the inter-individual correlation among growth and reproduction, using observations at individual level over several years combined with resource simulations from an ecophysiological-based model (CASTANEA). In the Bayesian model, the resource, simulated by CASTANEA and incorporated as a latent variable, is allocated to tree growth, reproductive buds initiation and fruit maturation. Then, we used individual random effects correlated among energetic sinks to investigate potential trade-offs. We applied this original approach to a Mediterranean coniferous tree, Atlas Cedar (Cedrus atlantica), at two contrasted levels of competition, high versus low density population. We found that trees initializing many reproductive buds had a higher growth. Moreover, a negative correlation was detected between growth and fruit survival during maturation. Finally, trees investing more resource to maturate fruits initiated less reproductive buds. The level of competition did not impact the sign of these three correlations, but changed the level of resource allocation: low density population favored growth whereas high density favored reproduction. The level of resource have an impact on individual strategies. This new modeling framework allowed us to detect various individual strategies of resource allocation to growth versus late-stage reproduction on the one hand, and to early-versus late-stage reproduction on the other hand. Moreover, the sign of the correlation between growth and reproductive traits depends on the stage of reproduction considered. Hence, we suggest that the investigation of potential trade-offs between growth and reproduction requires to integrate the dynamics of resource and sink’s phenology, from initiation to maturation of reproductive organs.

International audience; Key message: Few studies have linked the origin of dispersed tree seeds with their post-dispersal fate. We show that habitat-dependent mortality in a pedunculate oak (Quercus roburL.) seedling cohort reshapes the effective fecundity of individual mother trees but has little effect on the cohort's genetic diversity. Context : Initial tree recruitment plays a key role in forest regeneration, yet little is known on how patterns of recruit mortality feed back on the fecundity of reproducing trees. Aims : To investigate how among-habitat variation in seedling arrival and survival alters initial patterns of genetic diversity and maternal reproductive success. Methods : We genotyped a pedunculate oak seedling cohort (n = 809) and monitored it over 3 years. The mother trees of 81% of the seedlings were identified through parentage analysis. Seedlings were assigned to one of three habitats (broadleaved forest, pine plantation, or open area). Results : Broadleaved forest received most seedlings (approximate to 65%) but their survival was reduced by a third compared with pine plantations or open areas. Thus, mother trees dispersing many descendants to broadleaved forest suffered a disproportionate reduction of their reproductive success. Genetic diversity did not vary among habitats, nor over the monitoring period. Conclusion : The quality of seed dispersal, in terms of delivery sites, can considerably influence the reproductive success of individual mother trees without affecting the overall genetic diversity of the recruits.

R script and dataset used to run the hierarchical Bayesian model. See main text and SI for more details about the Bayesian model and its parameters. Inventory, forestry file and climate data use to run the CASTANEA model. Details are provided in the main article and Supporting Information. We use two inventory files and forestry file: one per plot density. The same climate file was used for both density plots. CASTANEA is an ecophysiological process-based model. We use the version available from the CAPSIS plateform (http://capsis.cirad.fr/capsis/models). Description of paramaters are available on the manual: https://www.overleaf.com/read/nmyvszjkfxxh

Understanding the ecological and evolutionary processes occurring during species range shifts is important in the current context of global change. Here, we investigate the interplay between recent expansion, gene flow and genetic drift, and their consequences for genetic diversity and structure at landscape and local scales in European beech (Fagus sylvatica L.) On Mont Ventoux, South-Eastern France, we located beech forest refugia at the time of the most recent population minimum, ~150 years ago, and sampled 71 populations (2042 trees) in both refugia and expanding populations over an area of 15,000 ha. We inferred patterns of gene flow and genetic structure using 12 microsatellite markers. We identified six plots as originating from planting, rather than natural establishment, mostly from local genetic material. Comparing genetic diversity and structure in refugia versus recent populations did not support the existence of founder effects: heterozygosity (He = 0.667) and allelic richness (Ar = 4.298) were similar, and FST was low (0.031 overall). Still, significant spatial evidence of colonization was detected, with He increasing along the expansion front, while genetic differentiation from the entire pool (βWT) decreased. Isolation by distance was found in refugia but not in recently expanding populations. Our study indicates that beech capacities for colonization and gene flow were sufficient to preserve genetic diversity despite recent forest contraction and expansion. Because beech has long distance pollen and seed dispersal, these results illustrate a 'best case scenario' for the maintenance of high genetic diversity and adaptive potential under climate-change-related range change.

International audience; The genetic composition of forest stands dynamically evolves driven by the combination of natural processes and management practices. Evolution-oriented forest management consists in understanding and stewarding these combined processes to enhance short-term adaptation and productivity while maintaining long-term evolvability.Silviculture is a sequence of practices, each having multiple possible genetic impacts, depending one on the other. Moreover, silvicultural practices interact with demographic changes due to other natural causes like environment changes. All these dependencies and interactions make an analytical approach of the resulting evolutionary dynamics, based on quantitative genetics, very complex. Here, we developed a demo-genetic simulation approach of this issue.Previous demo-genetic models in forest systems mainly focused on the possible impacts of silviculture on the overall (neutral) gene diversity. Here we focus on the selection effects on growth. We coupled a quantitative genetics model to a growth dynamics model calibrated for Cedrus atlantica, and simulated various scenarios of silviculture, using the CAPSIS simulation platform (http://capsis.cirad.fr/capsis/help_en/luberon2).We compared the effect of various management practices on (i) the growth, (ii) the genetic quality and (iii) the evolutionary potential of the stand. We show that different silviculture sequences may result in very different levels of selection intensity for growth, which have different impacts on the dynamics of genetic means and variances from one generation of trees to the next. We also show the importance of all stages of interventions, including those in the juvenile stage, on the final genetic impacts. Finally, we show that the effective genetic impacts of a given silviculture guideline are highly influenced by pragmatic choices in the forest and by local disturbance regimes.This work should be considered as a “proof of concept” showing that demo-genetic models coupling forest dynamics, quantitative genetics, silviculture practices and natural disturbances are feasible. Such models provide a powerful approach to investigate the potential genetic impacts of silviculture and guide evolution-oriented forest management. We are currently extending this approach to other species and other contexts.

International audience; Adaptation is a major stake of forest management in the climate change context The genetic diversity of forest trees confers them a huge – yet not boundless – adaptive potential Taking evolutionary mechanisms into account in adaptive forest management practices will reinforce the capacity of managed forests to respond to climate-induced changes and hazards By laying the emphasis on forests under natural regeneration conditions,we propose a general conceptual framework that includes knowledge on these mechanisms in decision- making processes, in a silvicultural approach through and for evolution This general framework will encompass diverse and complex local situations by relying on knowledge of local contexts from forest managers. We developed a simple analysis grid based on a small number of parameters characterising evolutionary mechanisms to understand the impact of silvicultural practices on the genetic diversity dynamics and the maintenance of the evolutionary potential of forest tree populations After recalling the current state of knowledge on the evolutionary mechanisms of forest trees, we examined the expected effects of current or innovative silvicultural practices on these mechanisms To illustrate the complexity of these interacting mechanisms, we further studied the evolutionary consequences of biotic interactions and of interactions in a highly heterogeneous environment Silviculture through and for evolution can contribute to the adaptation of forests to climate change This will require combining short-term and long-term objectives We further propose lines ofresearch and experimentation to support this approach.; L’adaptation est un enjeu majeur de la gestion forestière dans le contexte du changement climatique La diversité génétique qui caractérise les arbres forestiers leur confère un potentiel adaptatif très important mais pas illimité Prendre en compte les mécanismes de l’évolution dans les pratiques de gestion forestière adaptative renforcera la capacité des forêts gérées à répondre aux changements et aux aléas induits par le climat. En mettant l’accent sur le cas des forêts en régénération naturelle, nous proposons un cadre conceptuel général permettant d’intégrer la connaissance de ces mécanismes dans la prise de décision, dans une démarche de sylviculture par et pour l’évolution Ce cadre général pourra être décliné dans des situations locales diverses et complexes en s’appuyant sur la connaissance du contexte qu’ont les gestionnaires forestiers Nous développonsune grille d’analyse simple, basée sur un petit nombre de paramètres caractérisant les mécanismes de l’évolution, pour comprendre l’impact des pratiques sylvicoles sur la dynamique de la diversité génétique et le maintien du potentiel d’évolution des populations d’arbres forestiers Après avoir rappelé l’état des connaissances sur les mécanismes de l’évolution chez les arbres forestiers, nous examinons les effets attendus de pratiques forestières actuelles ou innovantes sur ces mécanismes Pour illustrer la complexité des mécanismes en interaction, nous développons plus en détail les conséquences évolutives des interactions biotiques et celles d’un environnement fortement hétérogène La sylviculture par et pour l’évolution peut contribuer à l’adaptation des forêts au changement climatique Elle nécessite de combiner des objectifs à court et à long terme Nous proposons des pistes de recherche et d’expérimentation pour accompagner cette démarche.

National audience; Recent interest for microgeographic adaptation, i.e. adaptation at spatial scales compatible with substantial amount of gene dispersal, offers to reconsider the scale at which evolution occurs (Richardson et al. 2014). Whether gene flow is constraining or facilitating local adaptation at this fine spatial scale remains an unresolved question. Too important gene flow would overwhelm the effects of natural selection and decrease local adaptation along environmental gradients. Conversely, gene flow, and particularly long-distance dispersal events, could play a major role in resupplying the genetic variation of populations and favouring the spread of beneficial alleles (Kremer et al. 2012). Hence, the high dispersal capacities of trees are often assumed to be the main process maintaining the large levels of genetic variation measured in their natural populations. However, evidences for microgeographic adaptation and the quantitative assessment of the impact of gene flow on adaptive genetic variation are still limited in most temperate trees. Here, we sampled 60 open-pollinated families of European beech (Fagus sylvatica L.) from three natural plots, spreading along a short elevation gradient (∼1.5 km) at the warm margin of this species distribution. We analysed the phenotypic and genotypic data of ∼2,300 seedlings grown in a common garden. We focused on 11 potentially adaptive traits with significant heritabilities (Gauzere et al. 2016) and tested for signature of local selection on quantitative trait differentiation. We then identified the offspring likely originating from local or distant pollen immigration events and quantified the role of gene flow in increasing locally the additive variance of traits under selection. We found a significant signal of adaptive differentiation among plots separated by less than one kilometre, with local selection acting on growth and phenological traits. We found that trees in the plots at high elevation, experiencing the lowest temperature conditions, flushed earlier and had a higher height and diameter growth in our common garden than trees from the plot at low elevation. Beech populations originating from higher longitude or elevation have also been shown to be genetically earlier in provenance tests, suggesting that these populations evolved phenological traits promoting a longer vegetation period. At this southern margin of the species, the reduced allocation to stem growth at the low elevation plot is likely an adaptive response to drought, which has previously been described by comparing marginal vs central beech populations. Consistently with theoretical expectations, our results suggest a beneficial effect of pollen dispersal by increasing the genetic diversity for these locally differentiated traits. These effects were quantitatively high, with more than twice higher genetic variance for immigrant than local offspring, although with large standard errors around estimates. Our results highlight that local selection is an important evolutionary force in natural tree populations, and provide a strong evidence that adaptive genetic differentiation can occur despite high gene flow. For the two genetically differentiated traits, our analyses suggested a beneficial effect of pollen dispersal by increasing genetic diversity after one episode of reproduction. The findings suggest that conservation and management interventions to facilitate movement of gametes along short ecological gradients would boost genetic diversity of individual tree populations, and thereby enhance their adaptive potential.

Forest fragmentation may affect mating and pollen dispersal patterns through conversion of continuous forests into small, spatially isolated remnant patches and individual trees in an anthropogenic landscape. We investigated reproductive investment and success, pollen dispersal, mating system, and genetic diversity and spatial structure of Qualea grandiflora trees in two environmental contexts: a continuous natural Cerrado area and isolated individuals on roadsides. Roadside trees produced more flowers and more fruit than Cerrado trees. Pollen dispersal kernels were fat-tailed in both contexts, indicating long-distance dispersal, but in Cerrado the mean pollen dispersal distance (524.7 m) and the effective number of pollen donors per mother-tree (Nep = 12.7) were higher than for roadside trees (60.9 m, Nep = 4.6). The levels and structure of genetic diversity, outcrossing rates ( $$t_{m}$$ > 0.98), and mating among relatives ( $$t_{m} - t_{s}$$ < 0.1) were similar in both environmental contexts. Allelic richness and number of private alleles were similar between the two environments. The fixation index was significantly lower in adults (minimum of 0.08) than in offspring (minimum of 0.23) in both contexts, suggesting selection against inbred individuals between offspring and adult stage. Our results indicate that the spatial isolation of roadside trees, by increasing the number of flowers produced, decreased pollinator movements, thereby reducing effective pollen flow and the number of pollen donors. All these results suggest that roadside trees can be used for harvesting seeds for recovery plans, and that these trees are a biological legacy, and reservoir of Q. grandiflora genetic diversity, from the original Cerrado forest.

Since several studies have been reporting an increase in the decline of forests, a major issue in ecology is to better understand and predict tree mortality. The interactions between the different factors and the physiological processes giving rise tree mortality, as well as the inter-individual variability in mortality risk, still need to be better assessed.This study investigates mortality in a rear-edge population of European beech (Fagus sylvatica L.) using a combination of statistical and process-based modelling approaches. Based on a survey of 4323 adult beeches since 2002 within a natural reserve, we first used statistical models to quantify the effects of competition, tree growth, size, defoliation and fungi presence on mortality. Secondly, we used an ecophysiological process-based model (PBM) to separate out the different mechanisms giving rise to temporal and inter-individual variations in mortality by simulating depletion of carbon stocks, loss of hydraulic conductance and damage due to late frosts in response to climate.The combination of all these simulated processes was associated with the temporal variations in the population mortality rate. The individual probability of mortality decreased with increasing mean growth, and increased with increasing crown defoliation, earliness of budburst, fungi presence and increasing competition, in the statistical model. Moreover, the interaction between tree size and defoliation was significant, indicating a stronger increase in mortality associated to defoliation in smaller than larger trees. Finally, the PBM predicted a higher conductance loss together with a higher level of carbon reserves for trees with earlier budburst, while the ability to defoliate the crown was found to limit the impact of hydraulic stress at the expense of the accumulation of carbon reserves.We discuss the convergences and divergences obtained between statistical and process-based approaches and we highlight the importance of combining them to characterize the different processes underlying mortality, and the factors modulating individual vulnerability to mortality.

Key message This review highlights some of the discoveries and applications made possible by “omics” technologies over the last 10 years and provides perspectives for pioneering research to increase our understanding of tree biology. Context A decade after the first forest tree genome sequence was released into the public domain, the rapidly evolving genomics and bioinformatics toolbox has advanced our understanding of the structure, functioning, and evolution of forest tree genomes. Aims and methods This review highlights some of the discoveries and applications that “omics” technologies have made possible for forest trees over the past 10 years. Results In this review, we start by our current understanding of genome evolution and intricacies of gene regulation for reproduction, development, and responses to biotic and abiotic stresses. We then skim over advances in interactome analysis and epigenomics, the knowledge of the extent of genetic variation within and between species, revealing micro- and macro-evolutionary processes and species history, together with the complex architecture of quantitative traits. We finally end with applications in genetic resource conservation and breeding. Conclusion The knowledge gained through the use of these technologies has a huge potential impact for adapting forests to the main challenges they will have to face: changing demand from ecosystem services with potentially conflicting strategies in terms of conservation and use, as well as climate changes and associated threats. Genomics will undoubtedly play a major role over the next decade and beyond, not only to further understand the mechanisms underlying adaptation and evolution but also to develop and implement innovative management and policy actions to preserve the adaptability of natural forests and intensively managed plantations.

Evolutionary processes are expected to be crucial for the adaptation of natural populations to environmental changes. In particular, the capacity of rear edge populations to evolve in response to the species limiting conditions remains a major issue that requires to address their evolutionary potential. In situ quantitative genetic studies based on molecular markers offer the possibility to estimate evolutionary potentials manipulating neither the environment nor the individuals on which phenotypes are measured. The goal of this study was to estimate heritability and genetic correlations of a suite of leaf functional traits involved in climate adaptation for a natural population of the tree Fagus sylvatica, growing at the rear edge of the species range. Using two marker-based quantitative genetics approaches, we obtained consistent and significant estimates of heritability for leaf phenological (phenology of leaf flush), morphological (mass, area, ratio mass/area) and physiological (δ(13)C, nitrogen content) traits. Moreover, we found only one significant positive genetic correlation between leaf area and leaf mass, which likely reflected mechanical constraints. We conclude first that the studied population has considerable genetic diversity for important ecophysiological traits regarding drought adaptation and, second, that genetic correlations are not likely to impose strong genetic constraints to future population evolution. Our results bring important insights into the question of the capacity of rear edge populations to evolve.

1- Global change is generating widespread local-scale expansions of tree populations. During demographic expansions, even small differences in individual reproductive success can generate large differences in the genetic composition of the resulting population. Colonizing tree populations almost invariably show highly skewed distributions of seed production, but the evolution of this reproductive skew during plant recruitment remains understudied.2- We examine how recruit mortality modifies initial patterns of acorn dispersal and maternal reproductive success in a recently established, expanding Pedunculate oak (Quercus robur) forest stand and test different predictors of successful recruit establishment.3- We mapped and genotyped a cohort of seedlings (n = 809) emerging within and around the stand (n = 254 adult trees), identified their habitats and monitored their fate until an age of 3 years. Their mother trees were inferred by Bayesian parentage analysis, and the number of assigned descendants was used as a proxy for tree maternal fertility. We examined temporal trends in tree fertility and patterns of dispersal, and tested effects of seed number-quality trade-offs, dispersal failure, dispersal distance and habitat of propagule arrival on the probability of seedling establishment.4- We observed marked inequality in maternal reproductive success at the time of seedling emergence. A positive relationship between tree fertility and the proportion of non-dispersed seedlings pointed to disperser satiation. An overall seedling mortality of 69% generated considerable reshuffling in the fertility ranking of individual trees. Non-dispersal more than doubled seedling mortality. The establishment success of actually dispersed seedlings was independent of mother fertility and dispersal distance but strongly related to the habitat of arrival. Recruit survival was markedly higher in pine plantations or non-forested areas than in broadleaved forest.5- Synthesis. A few highly fertile trees dominated reproduction in the stand. Differential recruitment success tended to reduce their initial advantage, however, suggesting that reproductive inequality might rapidly decline as more trees start to reproduce along the expansion process. Our results also suggest that field estimates of size or seed production are unlikely to provide reliable estimates of lifetime reproductive success in trees.

Q(ST) is a differentiation parameter based on the decomposition of the genetic variance of a trait. In the case of additive inheritance and absence of selection, it is analogous to the genic differentiation measured on individual loci, F(ST). Thus, Q(ST)−F(ST) comparison is used to infer selection: selective divergence when Q(ST) > F(ST), or convergence when Q(ST) < F(ST). The definition of Q-statistics was extended to two-level hierarchical population structures with Hardy–Weinberg equilibrium. Here, we generalize the Q-statistics framework to any hierarchical population structure. First, we developed the analytical definition of hierarchical Q-statistics for populations not at Hardy–Weinberg equilibrium. We show that the Q-statistics values obtained with the Hardy–Weinberg definition are lower than their corresponding F-statistics when F(IS) > 0 (higher when FIS < 0). Then, we used an island model simulation approach to investigate the impact of inbreeding and dominance on the Q(ST)−F(ST) framework in a hierarchical population structure. We show that, while differentiation at the lower hierarchical level (Q(SR)) is a monotonic function of migration, differentiation at the upper level (Q(RT)) is not. In the case of additive inheritance, we show that inbreeding inflates the variance of Q(RT), which can increase the frequency of Q(RT) > F(RT) cases. We also show that dominance drastically reduces Q-statistics below F-statistics for any level of the hierarchy. Therefore, high values of Q-statistics are good indicators of selection, but low values are not in the case of dominance.

A central issue in plant evolutionary ecology is to understand how several coordinated suites of traits (i.e. traits syndrome) may be jointly selected within a single species. This study aims to describe patterns of variation and co-variation of functional traits in a water-stressed tree population and test their relationships with performance traits. Within a Mediterranean population of Fagus sylvatica experiencing recurrent summer droughts, we investigated the phenotypic variation of leaf unfolding phenology, leaf area (LA), leaf mass per area (LMA), leaf water content (LWC), water use efficiency (WUE) estimated by carbon isotopic discrimination (d13C), twig Huber- value (HV: the stem cross-section divided by the leaf area distal to the stem), wood density (WDens), and leaf nitrogen content (Nmass). First, a principal component analysis revealed that two main axes structured the phenotypic variability: the first axis opposed leaf unfolding earliness and LWC to LMA and WUE; the second axis opposed LA to HV. These two axes can be interpreted as the opposition of two strategies (water economy versus water uptake) at two distinct scales (leaf for the first axis and branches for the second axis). Second, we found that LMA, LA, leaf unfolding and LWC responded differently to competition intensity, while WUE, WDens and HV did not correlate with competition. Third, we found that all studied functional traits were related to growth and/or reproductive performance traits and that these relationships were frequently non-linear, showing strong interactions between traits. By highlighting phenotypic clustering of functional traits involved in response to water stress and by evidencing antagonistic selection favouring intermediate trait values as well as trait combinations, our study brought new insights on how natural selection operates on plant functional traits in a stressful environment.

International audience; Understanding how invasive species establish and spread is vital for developing effective management strategies for invaded areas and identifying new areas where the risk of invasion is highest. We investigated the explanatory power of dispersal histories reconstructed based on local-scale wind data and a regionalscale wind-dispersed particle trajectory model for the invasive seed chalcid wasp Megastigmus schimitscheki (Hymenoptera: Torymidae) in France. The explanatory power was tested by: (1) survival analysis of empirical data on M. schimitscheki presence, absence and year of arrival at 52 stands of the wasp’s obligate hosts, Cedrus (true cedar trees); and (2) Approximate Bayesian analysis of M. schimitscheki genetic data using a coalescence model. The Bayesian demographic modeling and traditional population genetic analysis suggested that initial invasion across the range was the result of long-distance dispersal from the longest established sites. The survival analyses of the windborne expansion patterns derived from a particle dispersal model indicated that there was an informative correlation between the M. schimitscheki presence/absence data from the annual surveys and the scenarios based on regional-scale wind data. These three very different analyses produced highly congruent results supporting our proposal that wind is the most probable vector for passive long-distance dispersal of this invasive seed wasp. This result confirms that long-distance dispersal from introduction areas is a likely driver of secondary expansion of alien invasive species. Based on our results, management programs for this and other windborne invasive species may consider (1) focusing effort at the longest established sites and (2) monitoring outlying populations remains critically important due to their influence on rates of spread. We also suggest that there is a distinct need for new analysis methods that have the capacity to combine empirical spatiotemporal field data, genetic data, and environmental data to investigate dispersal and invasion

Finding outlier loci underlying local adaptation is challenging and is best approached by suitable sampling design and rigorous method selection. In this study, we aimed to detect outlier loci (single nucleotide polymorphisms, SNPs) at the local scale by using Aleppo pine (Pinus halepensis), a drought resistant conifer that has colonized many habitats in the Mediterranean Basin, as the model species. We used a nested sampling approach that considered replicated altitudinal gradients for three contrasting sites. We genotyped samples at 294 SNPs located in genomic regions selected to maximize outlier detection. We then applied three different statistical methodologies&mdash, Two Bayesian outlier methods and one latent factor principal component method&mdash, To identify outlier loci. No SNP was an outlier for all three methods, while eight SNPs were detected by at least two methods and 17 were detected only by one method. From the intersection of outlier SNPs, only one presented an allelic frequency pattern associated with the elevational gradient across the three sites. In a context of multiple populations under similar selective pressures, our results underline the need for careful examination of outliers detected in genomic scans before considering them as candidates for convergent adaptation.

Understanding the determinants of phenotypic variation is critical to evaluate the ability of traits to evolve in a changing environment. In trees, the genetic component of the phenotypic variance is most often estimated based on maternal progeny tests. However, the lack of knowledge about the paternal relatedness hampers the accurate estimation of additive genetic and maternal effects. Here, we investigate how different methods accounting for paternal relatedness allow the estimation of heritability and maternal determinants of adaptive traits in a natural population of Fagus sylvatica L., presenting non-random mating. Twelve potentially adaptive functional traits were measured in 60 maternal families in a nursery. We genotyped a subset of offspring and of all the potentially reproductive adults in the population at 13 microsatellite markers to infer paternal relationships and to estimate average relatedness within and between maternal families. This relatedness information was then used in family and animal models to estimate the components of phenotypic variance. All the studied traits displayed significant genetic variance and moderate heritability. Maternal effects were detected for the diameter increment, stem volume and bud burst. Comparison of family and animal models showed that unbalanced mating system led to only slight departures from maternal family assumptions in the progeny trial. However, neglecting the significant maternal effects led to an overestimation of the heritability. Overall, we highlighted the usefulness of relatedness pattern analyses using polymorphic molecular markers to accurately analyse tree sibling designs.

Q

International audience; Inter-individual variation in fecundities has major consequences on population evolutionary potential, through genetic drift and selection. Using two spatially explicit mating models that analyze the genotypes of seeds and seedlings, we investigated the variation of male and female fecundities within and among three European beech (Fagus sylvatica) stands situated along an altitudinal gradient. Female and male individual fecundity distributions were both skewed in this monoecious species, and we found a higher variance in female as compared to male fecundities. Both female and male fecundities increased with tree size and decreased with density and competition in the neighbourhood, the details of these effects suggesting sex-specific strategies to deal with the impact of limited resource on fecundity. The studied populations were functionally male-biased. Among-individual variations in functional gender were not driven by tree size but by density and competition in the neighbourhood. Femaleness decreased under limited resource availability, an expected consequence of the higher cost of female reproduction. Considering the variation of gene flow and genetic drift across elevation, our results suggest that the adaptive potential could be enhanced by low genetic drift at low elevation, and by high pollen-mediated gene flow at high elevation. Finally, this study predicts a more efficient response to selection for traits related to male versus female fitness, for a given selection intensity.

The evolutionary potential of long-lived species, such as forest trees, is fundamental for their local persistence under climate change (CC). Genome–environment association (GEA) analyses reveal if species in heterogeneous environments at the regional scale are under differential selection resulting in populations with potential preadaptation to CC within this area. In 79 natural [i]Fagus sylvatica[/i] populations, neutral genetic patterns were characterized using 12 simple sequence repeat (SSR) markers, and genomic variation (144 single nucleotide polymorphisms (SNPs) out of 52 candidate genes) was related to 87 environmental predictors in the latent factor mixed model, logistic regressions and isolation by distance/environmental (IBD/IBE) tests. SSR diversity revealed relatedness at up to 150m intertree distance but an absence of large-scale spatial genetic structure and IBE. In the GEA analyses, 16 SNPs in 10 genes responded to one or several environmental predictors and IBE, corrected for IBD, was confirmed. The GEA often reflected the proposed gene functions, including indications for adaptation to water availability and temperature. Genomic divergence and the lack of large-scale neutral genetic patterns suggest that gene flow allows the spread of advantageous alleles in adaptive genes. Thereby, adaptation processes are likely to take place in species occurring in heterogeneous environments, which might reduce their regional extinction risk under CC

Range expansion and contraction has occurred in the history of most species and can seriously impact patterns of genetic diversity. Historical data about range change are rare and generally appropriate for studies at large scales, whereas the individual pollen and seed dispersal events that form the basis of geneflow and colonization generally occur at a local scale. In this study, we investigated range change in Fagus sylvatica on Mont Ventoux, France, using historical data from 1838 to the present and approximate Bayesian computation (ABC) analyses of genetic data. From the historical data, we identified a population minimum in 1845 and located remnant populations at least 200 years old. The ABC analysis selected a demographic scenario with three populations, corresponding to two remnant populations and one area of recent expansion. It also identified expansion from a smaller ancestral population but did not find that this expansion followed a population bottleneck, as suggested by the historical data. Despite a strong support to the selected scenario for our data set, the ABC approach showed a low power to discriminate among scenarios on average and a low ability to accurately estimate effective population sizes and divergence dates, probably due to the temporal scale of the study. This study provides an unusual opportunity to test ABC analysis in a system with a well-documented demographic history and identify discrepancies between the results of historical, classical population genetic and ABC analyses. The results also provide valuable insights into genetic processes at work at a fine spatial and temporal scale in range change and colonization.

Negative frequency dependent selection (NFDS) is supposed to be the main force controlling allele evolution at the gametophytic self-incompatibility locus (S-locus) in strictly outcrossing species. Genetic drift also influences S-allele evolution. In perennial sessile organisms, evolution of allelic frequencies over two generations is mainly shaped by individual fecundities and spatial processes. Using wild cherry populations between two successive generations, we tested whether S-alleles evolved following NFDS qualitative and quantitative predictions. We showed that allelic variation was negatively correlated with parental allelic frequency as expected under NFDS. However, NFDS predictions in finite population failed to predict more than half S-allele quantitative evolution. We developed a spatially explicit mating model that included the S-locus. We studied the effects of self-incompatibility and local drift within populations due to pollen dispersal in spatially distributed individuals, and variation in male fecundity on male mating success and allelic frequency evolution. Male mating success was negatively related to male allelic frequency as expected under NFDS. Spatial genetic structure combined with self-incompatibility resulted in higher effective pollen dispersal. Limited pollen dispersal in structured distributions of individuals and genotypes and unequal pollen production significantly contributed to S-allele frequency evolution by creating local drift effects strong enough to counteract the NFDS effect on some alleles.

Trees' long lifespan, long-distance dispersal abilities and high year-to-year variability in fecundity are thought to have pervasive consequences for the demographic and genetic structure of recruited seedlings. However, we still lack experimental studies quantifying the respective roles of spatial processes such as restricted seed and pollen dispersal and temporal processes such as mast seeding on patterns of regeneration. Dynamics of European beech (Fagus sylvatica) seedling recruitment was monitored in three plots from 2004 to 2006. Six polymorphic microsatellite genetic markers were used to characterize seedlings and their potential parents in a 7.2-ha stand. These seedlings were shown to result from 12 years of recruitment, with one predominant year of seedling recruitment in 2002 and several years without significant recruitment. Using a spatially explicit mating model based on parentage assignment, short average dispersal distances for seed (δ(s) = 10.9 m) and pollen (43.7 m < δ(p)

Summary 1. Characterizing fine scale mating patterns in plant populations makes it possible to investigate genetic drift, gene flow and selection gradients at a contemporary time scale. Molecular markers are valuable tools for this type of analysis, and numerous statistical methods have been developed to make the best of the information they can provide. In particular, we recently proposed a Bayesian approach based on a paternity analysis wherein we estimate jointly the variance in male fecundity and the pollen dispersal kernel. 2. Here, we use simulated data sets to investigate the accuracy of the Bayesian approach compared to (i) classical maximum likelihood approaches (e.g. Neighbourhood model) that ignore variance in male fecundity or explain it through a few covariates and (ii) indirect methods (KinDist and TwoGener) that integrate the variance in fecundity in an ‘effective population density’. 3. The Bayesian estimates correctly considered the over-dispersion resulting from the variance in fecundity, resulting in wider but more accurate confidence intervals, in particular in high-density populations. The maximum likelihood methods resulted in confidence intervals with low coverage probabilities and in widespread false-positive tests when testing the effect of covariates on male fecundity. 4. Estimated individual fecundities and estimated empirical variance in fecundity were robust to the distribution assumed for the individual random fecundities (log-normal or Gamma). In contrast, the theoretical variance estimate critically depended on the assumed distribution. 5. The indirect methods provided much more variable estimators, as expected because they use less information about pollen sources and consider the molecular information only through genetic structure indices. 6. Disentangling the fecundity from the spatial effects in paternity analyses is necessary when studying selection in natura and or when addressing the effects of spatial distribution on effective gene flow. The Bayesian approach studied here successfully accounts for the variance in fecundity when a large fraction of it is not explained by the studied covariates. The Mixed Effect Mating Model computer program introduced here is devoted to its implementation.

The comparison between estimates of historical gene flow, using variance in allelic frequencies, and estimates of contemporary gene flow, using parentage assignment, is expected to provide insights into ecological and evolutionary processes at work within and among populations. Genetic variation at microsatellite loci was used to quantify genetic structure in two wind pollinated, gravity and animal-dispersed tree species (Fagus sylvatica L. and Fagus crenata Blum.) and to derive historical estimates of gene flow. The gene dispersal distances estimated assuming effective population density to be 1/4 of the observed density were ∼77 m in European beech and ∼40 m in Japanese beech. Parentage analyses and a neighbourhood model approach were used to estimate contemporary patterns of seed and pollen dispersal. Our results suggest restricted seed dispersal abilities in both European beech (δs = 10.5 m) and Japanese beech (δs = 12.4 m), with an exponential shaped seed dispersal kernel. A non-negligible rate of seed immigration (ms = 27%) was detected in European beech sites but not in Japanese beech site. Pollen dispersal within studied sites also appeared limited (δp = 41.63 m in European beech and δp = 79.4 m in Japanese beech), despite high rate of pollen immigration (mp = 68% in European beech and mp = 40% m in Japanese beech). Interestingly, contemporary and historical estimates of gene flow were within the same order of magnitude (a few tens of meters).

Interindividual variance of male reproductive success (MRS) contributes to genetic drift, which in turn interacts with selection and migration to determine the short-term response of populations to rapid changes in their environment. Individual relative MRS can be estimated through paternity analysis and can be further dissected into fecundity and spatial components. Existing methods to achieve this decomposition either rely on the strong assumption of a random distribution of pollen donors (TwoGener) or estimate only the part of the variance of male fecundity that is explained by few covariates. We developed here a method to estimate jointly the whole variance of male fecundity and the pollen dispersal curve from the genotypic information of sampled seeds and their putative fathers and geographical information of all individuals in the study area. We modelled the relative individual fecundities as a log-normally distributed random effect. We used a Bayesian approach, well suited to the hierarchical nature of the model, to estimate these fecundities. When applied to Sorbus torminalis, the estimated variance of male fecundity corresponded to an effective density of trees 13 times lower than the observed density (d(obs)/d(ep ) approximately 13). This value is between the value (approximately 2) estimated with a classical mating model including three covariates (neighbourhood density, diameter, flowering intensity) that affect fecundity and the value (approximately 30) estimated with TwoGener. The estimated dispersal kernel was close to previous results. This approach allows fine monitoring of ongoing genetic drift in natural populations, and quantitative dissection of the processes contributing to drift, including human actions.

The comparison between historical estimates of gene flow, using variance in allelic frequencies, and contemporary estimates of gene flow, using parentage assignment, is expected to provide insights into ecological and evolutionary processes at work within and among populations. Genetic variation at six microsatellite loci was used to quantify genetic structure in the insect-pollinated, animal-dispersed, low-density tree Sorbus torminalis L. Crantz, and to derive historical estimates of gene flow. The neighbourhood size and root-mean-squared dispersal distance inferred from seedling genotypes (Nb = 70 individuals, σe = 417 m) were similar to those inferred from adult genotypes (Nb = 114 individuals, σe = 472 m). We also used parentage analyses and a neighbourhood model approach after an evaluation of the statistical properties of this method on simulated data. From our data, we estimated even contributions of seed- and pollen-mediated dispersal to the genetic composition of established seedlings, with both fat-tailed pollen and seed dispersal kernels, and slightly higher mean distance of pollen dispersal (248 m) as compared to seed dispersal (135 m). The resulting contemporary estimate of gene dispersal distance (σc = 211 m) was ∼twofold smaller than the historical estimates. Besides different assumptions and statistical nuances of both approaches, this discrepancy is likely to reflect a recent restriction in the scale of gene flow which requires manager's attention in a context of increasing forest fragmentation.

Understanding local adaptation in forest trees is currently a key research and societal priority. Geographically and ecologically marginal populations provide ideal case studies, because environmental stress along with reduced gene flow can facilitate the establishment of locally adapted populations. We sampled European silver fir (Abies alba Mill.) trees in the French Mediterranean Alps, along the margin of its distribution range, from pairs of high- and low-elevation plots on four different mountains situated along a 170-km east-west transect. The analysis of 267 SNP loci from 175 candidate genes suggested a neutral pattern of east-west isolation by distance among mountain sites. F(ST) outlier tests revealed 16 SNPs that showed patterns of divergent selection. Plot climate was characterized using both in situ measurements and gridded data that revealed marked differences between and within mountains with different trends depending on the season. Association between allelic frequencies and bioclimatic variables revealed eight genes that contained candidate SNPs, of which two were also detected using F(ST) outlier methods. All SNPs were associated with winter drought, and one of them showed strong evidence of selection with respect to elevation. Q(ST)-F(ST) tests for fitness-related traits measured in a common garden suggested adaptive divergence for the date of bud flush and for growth rate. Overall, our results suggest a complex adaptive picture for A. alba in the southern French Alps where, during the east-to-west Holocene recolonization, locally advantageous genetic variants established at both the landscape and local scales.

Knowing the extent of gene movements from parents to offspring is essential to understand the potential of a species to adapt rapidly to a changing environment, and to design appropriate conservation strategies. In this study, we develop a nonlinear statistical model to jointly estimate the pollen dispersal kernel and the heterogeneity in fecundity among phenotypically or environmentally defined groups of males. This model uses genotype data from a sample of fruiting plants, a sample of seeds harvested on each of these plants, and all males within a circumscribed area. We apply this model to a scattered, entomophilous woody species, Sorbus torminalis (L.) Crantz, within a natural population covering more than 470 ha. We estimate a high heterogeneity in male fecundity among ecological groups, both due to phenotype (size of the trees and flowering intensity) and landscape factors (stand density within the neighbourhood). We also show that fat-tailed kernels are the most appropriate to depict the important abilities of long-distance pollen dispersal for this species. Finally, our results reveal that the spatial position of a male with respect to females affects as much its mating success as ecological determinants of male fecundity. Our study thus stresses the interest to account for the dispersal kernel when estimating heterogeneity in male fecundity, and reciprocally.

Sorbus torminalis L. Crantz is a colonizing tree species usually found at low density in managed European forests. Using six microsatellite markers, we investigated spatial and temporal patterns of genetic structure within a 472-ha population of 185 individuals to infer processes shaping the distribution of genetic diversity. Only eight young stems were found to be the result of vegetative reproduction. Despite high levels of gene flow (standard deviation of gene dispersal = 360 m), marked patterns of isolation by distance were detected, associated with an aggregated distribution of individuals in approximately 100-m patches. This spatial structure of both genes and individuals is likely to result from patterns of seedling recruitment combined with low tree density. Our results suggest that landscape factors and logging cycles markedly shape the distribution of favourable sites for seedling establishment, which are then colonized by sibling cohorts as a result of joint seed transportation by frugivores. These combined genetic and demographic processes result in similar genetic structure both within and among logging units. However, conversion to high forest may enhance genetic structuring.

Understanding precisely how plants disperse their seeds and pollen in their neighbourhood is a central question for both ecologists and evolutionary biologists because seed and pollen dispersal governs both the rate of spread of an expanding population and gene flow within and among populations. The concept of a ‘dispersal kernel’ has become extremely popular in dispersal ecology as a tool that summarizes how dispersal distributes individuals and genes in space and at a given scale. In this issue of Molecular Ecology, the study by Moran & Clark (2011) (M&C in the following) shows how genotypic and spatial data of established seedlings can be analysed in a Bayesian framework to estimate jointly the pollen and seed dispersal kernels and finally derive a parentage analysis from a full-probability approach. This approach applied to red oak shows important dispersal of seeds (138 m on average) and pollen (178 m on average). For seeds, this estimate contrasts with previous results from inverse modelling on seed trap data (9.3 m). This research gathers several methodological advances made in recent years in two research communities and could become a cornerstone for dispersal ecology.

European beech (Fagus sylvatica L.) is one of the most economically and ecologically important deciduous trees in Europe, yet little is known about its genomic diversity and its adaptive potential. Here, we detail the discovery and analysis of 573 single nucleotide polymorphisms (SNPs) from 58 candidate gene fragments that are potentially involved in abiotic stress response and budburst phenology using a panel of 96 individuals from southeastern France. The mean nucleotide diversity was low (θ π = 2.2 × 10-3) but extremely variable among gene fragments (range from 0.02 to 10), with genes carrying insertion/deletion mutations exhibiting significantly higher diversity. The decay of linkage disequilibrium (LD) measured at gene fragments >800 base pairs was moderate (the half distance of r 2 was 154 bp), consistent with the low average population-scaled recombination rate (ρ = 5.4 × 10-3). Overall, the population-scaled recombination rate estimated in F. sylvatica was lower than for other angiosperm tree genera (such as Quercus or Populus) and similar to conifers. As a methodological perspective, we explored the effect of minimum allele frequency (MAF) on LD and showed that higher MAF resulted in slower decay of LD. It is thus essential that the same MAF is used when comparing the decay of LD among different studies and species. Our results suggest that genome-wide association mapping can be a potentially efficient approach in F. sylvatica, which has a relatively small genome size. © 2013 Springer-Verlag Berlin Heidelberg.

International audience; & Context Managing forests under climate change requires adaptation. The adaptive capacity of forest tree populations is huge but not limitless. Integrating evolutionary consider-ations into adaptive forestry practice will enhance the ca-pacity of managed forests to respond to climate-driven changes. & Aims Focusing on natural regeneration systems, we pro-pose a general framework that can be used in various and complex local situations by forest managers, in combination with their own expertise, to integrate evolutionary consid-erations into decision making for the emergence of an evolution-oriented forestry. & Methods We develop a simple process-based analytical grid, using few processes and parameters, to analyse the impact of forestry practice on the evolution and evolvability of tree populations. & Results We review qualitative and, whenever possible, quantitative expectations on the intensity of evolutionary drivers in forest trees. Then, we review the effects of actual and potential forestry practice on the evolutionary processes. We illustrate the complexity of interactions in two study cases: the evolutionary consequences for forest trees of biotic in-teractions and of highly heterogeneous environment. & Conclusion Evolution-oriented forestry may contribute adapting forests to climate change. It requires combining short-term and long-term objectives. We propose future lines of research and experimentation.

One challenge of evolutionary ecology is to predict the rate and mechanisms of population adaptation to environmental variations. The variations in most life-history traits are shaped both by individual genotypic and environmental variation. Forest trees exhibit high levels of genetic diversity, large population sizes, and gene flow, and they also show a high level of plasticity for life-history traits. We developed a new Physio-Demo-Genetics model (denoted PDG) coupling (1) a physiological module simulating individual tree responses to the environment; (2) a demographic module simulating tree survival, reproduction and pollen and seed dispersal; and (3) a quantitative genetics module controlling the heritability of key life history traits. We used this model to investigate the plastic and genetic components of the variations of the timing of budburst along an elevational gradient of Fagus sylvatica (the European beech). We used a repeated five years climatic sequence to show that five generations of natural selection were sufficient to develop non-monotonic genetic differentiation in the timing of budburst along the local climatic gradient but also that plastic variation among different elevations and years was higher than genetic variation. PDG complements theoretical models and provides testable predictions to understand the adaptive potential of tree populations

International audience; Studies addressing the variation of mating system between plant populations rarely account for the variability of these parameters between individuals within populations, although this variability is often non-negligible. Here, we propose a new direct method based on paternity analyses (Mixed Effect Mating Model) to estimate individual migration (m(i)) and selfing rates (s(i)) together with the pollen dispersal kernel. Using this method and the KINDIST approach, we investigated the variation of mating system parameters within and between three populations of Fagus sylvatica along an elevational gradient. Among the mother trees, s(i) varied from 0% to 48%, m(i) varied from 12% to 86% and the effective number of pollen donors (Nep(i)) varied from 2 to 364. The mating patterns differed along the gradient, the top population showing higher m and lower s, and a trend to higher Nep than the bottom populations. The phenological lag shaped long-distance pollen flow both within population (by increasing m(i) at mother-tree level) and between populations (by increasing m at high elevation). Rather than the mate density, the canopy density was detected as a major mating system determinant within population; it acted as a barrier to pollen flow, decreasing the proportion of long-distance pollen flow and increasing s(i). Overall, the effects of ecological factors on mating system were not the same within vs. between populations across the gradient, and these factors also differed from those traditionally found to shape variation at range-wide scale, highlighting the interest of multiscale approaches.