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E4E Evolution in Forest Ecosystems

Team leaders : Benjamin Brachi & Marta Benito

Manager : Florence Le Pierres

Background and motivation

Forests are dynamic systems where the environment changes over broadly different temporal scales. For example climate and soil composition can change over hundreds to millions of years whereas communities and micro-environmental conditions can vary over just a few years to decades. Global change can exacerbate those changes and disrupt temporal scales. 

Evolutionary biology aims to study changes in allele frequencies between generations whereas ecology studies demographic fluctuations and changes in ecological interactions. The difference between ecological and evolutionary time scales has long been a rationale for keeping these disciplines separated. However, evolutionary and ecological processes can take place over similar time scales. Recent results in many organisms, including forest trees,  showed that natural selection can be strong and that its effects are observed over a single or few generations. As a consequence, ecological changes can drive evolutionary change, and phenotypic changes induced by natural selection can influence ecological processes such as population demography (density and diversity) or biotic interactions at the scale of ecosystems.  

In this context, our goal is to study ecological and evolutionary processes in an integrated manner in temperate, mediterranean and tropical forest ecosystems. From a more finalized point of view, these research topics should help better characterize the adaptive potential of forest tree populations, contribute to conservation and sustainable use of forest genetic resources, and propose forest management solutions taking into account evolutionary and ecological processes. 

Objectives and scientific strategy

The main objectives of the group are:

1. Determine the relative contribution of local adaptation and demographic history in shaping natural variation in forest tree populations and identify the environmental drivers of natural selection. 
2. Study the relationships between phenotypic and genetic micro-evolutionary changes
3. Study variation in functional traits using biogeographical approaches to better understand changes in species composition of forests along environmental gradients.
4. Understand how phenotypic and genetic variation are maintained within populations. 
5. Understand how phenotypic plasticity can be adaptive and quantify its role in the persistence and resilience of populations.
6. Quantify gene flow and hybridization and its contribution to the adaptive potential of populations
7. Identify molecular functions and regulatory mechanisms contributing to the natural variation of adaptive phenotypes

Our investigations are centered around the concept of the adaptive landscape, which is the fitness of individuals in the space of possible phenotypic values. We are mostly interested in the spatial and temporal dynamics of this adaptive landscape. In particular we study how ecological processes like competition or predation interact to shape the natural variation of fitness-related traits.

Impacts

Our research will contribute to understanding, for example, how moving forest genetic resources according to climate predictions could promote or impair the resilience of forest ecosystems, both planted and naturally regenerated. Most forests in France regenerate naturally, and individuals harvested are generally chosen based on shape and size criteria. This type of anthropic selection may lead to losses of phenotypic diversity for adaptive traits and affect intraspecific competition and interactions with the forest-associated community. Similarly, in the tropics, conservation and restoration efforts need to account for the functional role of phenotypic variation between and within species, and ensure sufficient diversity is maintained for ecosystem stability and resilience. Eventually, our research will help evaluate silvicultural practices on the maintenance and evolution of genetic and phenotypic diversity. 

Keywords

Ecology, Evolution, Forest trees, Genetic, Genomic, Biogeography, Ecophysiology, Biotic interactions

Staff members