Fluctuating selection and rapid evolution of oaks during recent climatic transitions

International audienceSocietal Impact Statement The rapidity of evolutionary changes in trees and whether this pace is sufficient to cope with ongoing climatic change are hotly debated issues in ecology today. Climate warming began in the mid‐19th century, after the Little Ice Age (LIA). Monitoring temporal genetic changes during this climatic transition in multicentennial oak populations revealed evidence of fluctuating selection and rapid evolution. These findings suggest that rapid evolution is probably also currently underway. They may lead to management options for operational forestry aiming to stimulate evolutionary mechanisms during the renewal of oak stands and to decrease potential temporal gene flow. Summary Retrospective studies of the evolutionary responses of tree populations to past documented climate change can provide insight into the adaptive responses of these organisms to ongoing environmental changes. We used a retrospective approach to monitor genetic changes over time in multicentennial sessile oak ( Quercus petraea L.) forests. We compared the offspring of three age‐structured cohorts (340, 170, and 60 years old, dating from about 1680, 1850, and 1960) spanning the late Little Ice Age and early Anthropocene. The experiment was repeated in three different forests in western France. The offspring were raised in a common garden experiment, with 30 to 53 open‐pollinated families per cohort. We assessed 16 phenotypic traits in the common garden and observed significant shifts between cohorts for growth and phenology‐related traits. These shifts were correlated with differences in the prevailing temperatures in the past and could be interpreted as temporal genetic changes. However, there was no temporal trend for genetic variation. The genetic changes between the cold (late Little Ice Age) and warm (early Anthropocene) periods were mostly opposite for growth and phenology‐related traits. These findings highlight fluctuations of selection and a rapid evolutionary response of tree populations to climatic transitions in the past, suggesting that similar trends may be at work now. We discuss these results in terms of the mode and direction of evolution, and their potential implications for the adaptive management of oak forests.La vitesse d'évolution des arbres et leur capacité à répondre au changement climatique sont très largement débattues aujourd'hui en écologie et en biologie évolutive. Dans cet article les auteurs ont mesuré les changements génétiques sur des chênes sessiles ayant traversé la transition climatique depuis la fin du petit âge glaciaire jusqu'à l'époque actuelle (de 1660 à nos jours). Les résultats montrent que les chênes ont évolué rapidement, sous l'effet de pressions de sélection contrastées lors de cette transition. Ils concluent que les mécanismes d'évolution rapide sont également à l'œuvre à l'époque actuelle, sous l'effet du changement climatique en cours et discutent de leur activation par la gestion forestière

Genetic differentiation in functional traits among European sessile oak populations

The vulnerability of forest species and tree populations to climate change is related to the exposure of the ecosystem to extreme climatic conditions and to the adaptive capacity of the population to cope with those conditions. Adaptive capacity is a relatively under-researched topic within the forest science community and there is an urgent need to understand to what extent particular combinations of traits have been shaped by natural selection under climatic gradients, potentially resulting in adaptive multi-trait associations. Thus, our aim was to quantify genetic variation in several leaf and woody traits that may contribute to multi-trait associations in which intraspecific variation could represent a source for species adaptation to climate change. A multi-trait approach was performed using nine Quercus petraea provenances originating from different locations that cover most of the species' distribution range over Europe and that were grown in a common garden. Multiple adaptive differences were observed between oak provenances but also some evolutionary stasis. Also, our results revealed higher genetic differentiation in traits related to phenology and growth than in those related to xylem anatomy, physiology and hydraulics for which no genetic differentiation was observed. The multiple associations between those traits and climate variables resulting from multivariate and path analyses suggest a multi-trait association largely involving phenological and growth traits for Quercus petraea. © The Author(s) 2019. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: [email protected]

Évolution passée et contemporaine des chênes

International audienceThe present review takes stock of recently acquired knowledge on the evolution of European white oaks, from their origin and the diversification of the genus Quercus up to their contemporary evolution, notably in link with the evolution of climate. We recall the way these advances were made possible thanks to the improvement of the theoretical and methodological methods for studying genomes and the improvement of the sciencesof evolution. For example, paleontological data coupled with population genetics methods made it possible to better date the emergence of European white oaks and understand their evolutionary history. European white oaks progressively differentiated from one another from a genetic point of view; but the end of the last glacial period brought them into contact, and a massive exchange of genes ensued. This new pathway contributedto homogenise the genomes of these species, except in a few precise zones of their genomes that explain current ecological preferences and other observable differences across species. These genetic exchanges also led to the transfer of adaptations among species; e.g. for example, sessile oak grew adapted to altitude. Finally, at a contemporary time scale, our analyses reveal that genetic and demographic changes occurred within two generations in sessile oak and pedunculate oak. To conclude, the review suggests possible applications of these results to the management and conservation of oak groves.Dans cette revue, nous faisons le point sur les connaissances récentes acquises sur l’évolution des chênes blancs européens, depuis les origines et la diversification du genre Quercus jusqu’à leur évolution contemporaine, notamment en lien avec l’évolution du climat. Nous rappelons comment ces avancées ont été rendues possibles par l’amélioration des méthodes théoriques et méthodologiques pour l’étude des génomes et des sciences de l’évolution. Les données paléontologiques, couplées à des méthodes de génétique des populations, ont par exemple permis de mieux dater l’émergence des chênes blancs européens et de comprendre leur histoire évolutive. Les chênes blancs européens se sont progressivement différenciés génétiquement les uns des autres ; mais à la fin de la dernière période glaciaire ils se sont retrouvés en contact et ont échangémassivement des gènes entre eux. Ce changement de trajectoire a contribué à homogénéiser les génomes de ces espèces, sauf à quelques zones précises de leur génome, expliquant les préférences écologiques et autres différences toujours observables entre elles. Ces échanges génétiques ont aussi conduit à transférer des adaptations entre espèces, comme par exemple l’adaptation à l’altitude du Chêne sessile. Enfin, à une échellecontemporaine, nos analyses révèlent les changements génétiques et démographiques sur deux générations chez le Chêne sessile et chez le Chêne pédonculé. En conclusion, cette revue évoque des applications possibles de ces résultats dans la gestion et la conservation des chênaies

Die Evolution der Eichen in Vergangenheit und Neuzeit

Dans cette revue, nous faisons le point sur les connaissances récentes acquises sur l’évolution des chênes blancs européens, depuis les origines et la diversification du genre Quercus jusqu’à leur évolution contemporaine, notamment en lien avec l’évolution du climat. Nous rappelons comment ces avancées ont été rendues possibles par l’amélioration des méthodes théoriques et méthodologiques pour l’étude des génomes et des sciences de l’évolution. Les données paléontologiques, couplées à des méthodes de génétique des populations, ont par exemple permis de mieux dater l’émergence des chênes blancs européens et de comprendre leur histoire évolutive. Les chênes blancs européens se sont progressivement différenciés génétiquement les uns des autres ; mais à la fin de la dernière période glaciaire ils se sont retrouvés en contact et ont échangémassivement des gènes entre eux. Ce changement de trajectoire a contribué à homogénéiser les génomes de ces espèces, sauf à quelques zones précises de leur génome, expliquant les préférences écologiques et autres différences toujours observables entre elles. Ces échanges génétiques ont aussi conduit à transférer des adaptations entre espèces, comme par exemple l’adaptation à l’altitude du Chêne sessile. Enfin, à une échellecontemporaine, nos analyses révèlent les changements génétiques et démographiques sur deux générations chez le Chêne sessile et chez le Chêne pédonculé. En conclusion, cette revue évoque des applications possibles de ces résultats dans la gestion et la conservation des chênaies.The present review takes stock of recently acquired knowledge on the evolution of European white oaks, from their origin and the diversification of the genus Quercus up to their contemporary evolution, notably in link with the evolution of climate. We recall the way these advances were made possible thanks to the improvement of the theoretical and methodological methods for studying genomes and the improvement of the sciencesof evolution. For example, paleontological data coupled with population genetics methods made it possible to better date the emergence of European white oaks and understand their evolutionary history. European white oaks progressively differentiated from one another from a genetic point of view; but the end of the last glacial period brought them into contact, and a massive exchange of genes ensued. This new pathway contributedto homogenise the genomes of these species, except in a few precise zones of their genomes that explain current ecological preferences and other observable differences across species. These genetic exchanges also led to the transfer of adaptations among species; e.g. for example, sessile oak grew adapted to altitude. Finally, at a contemporary time scale, our analyses reveal that genetic and demographic changes occurred within two generations in sessile oak and pedunculate oak. To conclude, the review suggests possible applications of these results to the management and conservation of oak groves

In situ estimation of genetic variation of functional and ecological traits in Quercus petraea and Q. robur

Predicting the evolutionary potential of natural tree populations requires the estimation of heritability and genetic correlations among traits on which selection acts, as differences in evolutionary success between species may rely on differences for these genetic parameters. In situ estimates are expected to be more accurate than measures done under controlled conditions which do not reflect the natural environmental variance. The aim of the current study was to estimate three genetic parameters (i.e., heritability, evolvability, and genetic correlations) in a natural mixed oak stand composed of Quercus petraea and Quercus robur about 100 years old, for 58 traits of ecological, and functional relevance (growth, reproduction, phenology, physiology, resilience, structure, morphology, and defense). First, we estimated genetic parameters directly in situ using realized genomic relatedness of adult trees and parentage relationships over two generations to estimate the traits' additive variance. Secondly, we benefited from existing ex situ experiments (progeny tests and conservation collection) installed with the same populations, thus allowing comparisons of in situ heritability estimates with more traditional methods. Heritability and evolvability estimates obtained with different methods varied substantially and showed large confidence intervals; however, we found that in situ were less precise than ex situ estimates, and assessments over two generations (with deeper relatedness) improved estimates of heritability while large sampling sizes are needed for accurate estimations. At the biological level, heritability values varied moderately across different ecological and functional categories of traits, and genetic correlations among traits were conserved over the two species. We identified limits for using realized genomic relatedness in natural stands to estimate the genetic variance, given the overall low variance of genetic relatedness and the rather low sampling sizes of currently used long-term genetic plots in forestry. These limits can be overcome if larger sample sizes are considered, or if the approach is extended over the next generation

<em>In situ</em> estimation of genetic variation of functional and ecological traits in <em>Quercus petraea</em> and <em>Q. robur</em>

background: Predicting the evolutionary potential of natural tree populations requires the estimation of heritability and genetic correlations among traits on which selection acts, as di erences in evolutionary success between species may rely on di erences for these genetic parameters. In situ estimates are expected to be more accurate than measures done under controlled conditions which do not re ect the natural environmental variance. aims: The aim of the current study was to estimate three genetic parameters (i.e. heritability, evolvability and genetic correlations) in a natural mixed oak stand composed of Quercus petraea and Quercus robur about 100 years old, for 58 traits of ecological and functional relevance (growth, reproduction, phenology, physiology, resilience, structure, morphology and defence). methods: First we estimated genetic parameters directly in situ using realized genomic relatedness of adult trees and parentage relationships over two generations to estimate the traits additive variance. Secondly, we bene ted from existing ex situ experiments (progeny tests and conservation collection) installed with the same populations, thus allowing comparisons of in situ heritability estimates with more traditional methods. results: Heritability and evolvability estimates obtained with di erent methods varied substantially and showed large con dence intervals, however we found that in situ were less precise than ex situ estimates, and assessments over two generations (with deeper relatedness) improved estimates of heritability while large sampling sizes are needed for accurate estimations. At the biological level, heritability values varied moderately across di erent ecological and functional categories of traits, and genetic correlations among traits were conserved over the two species. conclusion: We identi ed limits for using realized genomic relatedness in natural stands to estimate the genetic variance, given the overall low variance of genetic relatedness and the rather low sampling sizes of currently used long term genetic plots in forestry. These limits can be overcome if larger sample sizes are considered, or if the approach is extended over the next generation.From Holocene to Anthropocene: the pace of microevolution in tree

Assessing inter- and intraspecific variability of xylem vulnerability to embolism in oaks

The genus Quercus comprises important species in forestry not only for their productive value but also for their ability to withstand drought. Hence an evaluation of inter- and intraspecific variation in drought tolerance is important for selecting the best adapted species and provenances for future afforestation. However, the presence of long vessels makes it difficult to assess xylem vulnerability to embolism in these species. Thanks to the development of a flow centrifuge equipped with a large rotor, we quantified (i) the between species variability of embolism resistance in four native and two exotic species of oaks in Europe and (ii) the within species variability in Quercus petraea. Embolism resistance varied significantly between species, with the pressure inducing 50% loss of hydraulic conductivity (P-50) ranging between -7.0 and -4.2 MPa. Species native to the Mediterranean region were more resistant than pan-European species. In contrast, intraspecific variability in embolism resistance in Q. petraea was low within provenances and null between provenances. A positive correlation between P-50 and vessel diameter among the six oak species indicates that the more embolism resistant species had narrower xylem vessels and a higher amount of hydraulic bridges between vessels. However, this tradeoff between hydraulic efficiency and safety was not observed between Q. petraea provenances

How does contemporary selection shape oak phenotypes?

Most existing forests are subjected to natural and human-mediated selection pressures, which have increased due to climate change and the increasing needs of human societies for wood, fibre and fuel resources. It remains largely unknown how these pressures trigger evolutionary changes. We address this issue here for temperate European oaks (Quercus petraeaandQ. robur), which grow in mixed stands, under even-aged management regimes. We screened numerous functional traits for univariate selection gradients and for expected and observed genetic changes over two successive generations. In both species, growth, leaf morphology and physiology, and defence-related traits displayed significant selection gradients and predicted shifts, whereas phenology, water metabolism, structure and resilience-related traits did not. However, the direction of the selection response and the potential for adaptive evolution differed between the two species.Quercus petraeahad a much larger phenotypic and genetic variance of fitness thanQ. robur. This difference raises concerns about the adaptive response ofQ. roburto contemporary selection pressures. Our investigations suggest thatQ. roburwill probably decline steadily, particularly in mixed stands withQ. petraea, consistent with the contrasting demographic dynamics of the two species

Musique concrète, French New Wave cinema, and Jean Cocteau's 'Le Testament d'Orphée' (1960)

Jean Cocteau (1889–1963) is recognized as one of France's most well-known film directors, directing six films over a thirty-year period. This article argues that his film soundscapes occupy a unique position in the history of French film sound, providing a key link between contemporary experimentation in art music and the sonic experimentation of the New Wave filmmakers. This argument is best exemplified by Le Testament d'Orphée (1960), which represents the apotheosis of Cocteau's artistic output as well as the stage at which he was most confident in handling the design of a film soundscape. Indeed, Cocteau was comfortable with the selection and arrangement of sonic elements to the extent that his regular collaborator Georges Auric became almost dispensable. Nevertheless, Auric's willing support enriched the final film and Cocteau created a highly self-reflexive work through his arrangement of the composer's music with pre-existing musical borrowings. Cocteau's engagement with contemporary developments in film and art music can be heard throughout this film, highlighting his position as a poet simultaneously establishing himself in the canon of art and looking to the future