Among population trait diversity (Qst) andwithin-population genetic diversity (Hs) evolveunder natural selection in an heterogeneousenvironment. Local adaptation occurs veryquickly during the first few generations whilegenetic diversity decreases only slowly, bufferedby sexual reproduction. Thus, selection does notdirectly result in the erosion of geneticdiversity, and in some cases will be protected atthe meta-population scale. The dynamics oflocal adaptation and erosion of genetic diversitydepend on selection intensity, geneticarchitecture of the traits under selection andhabitat heterogeneity.

Simulated data are produced using an individual process-based model that includes reproduction, dispersal and growth. When mortality is not modeled (black bars), the range shrinks only slightly

at the rear edge and the species does not go extinct. When mortality is modeled and dieback is included (red bars), the upward migration at the tree line (blue arrows) under different temperature warming scenarios (+ 0°C, +2°C, +3.5°C and 6°C) is slower than extinction at the rear-edge, leading to a retraction of the range by 2100. If temperature increases beyond 5°C, the species will go extinct by 2100.

In this individual-based Physio-Demo-Geneticmodel, budburst date is genetically determined byTsum (the sum of temperature since Jan 1st atwhich budburst occurs, coded by 10 loci). Among-individual differences in mortality andreproduction dynamically emerge from naturalselection.A- Without natural selection, no geneticdifferentiation of Tsum occurs and the altitudinaldistribution of Tsum after 5 generations (G5) ofcolonization is that of G0, unchanged.B- With natural selection, populations at differentaltitudes diverge. Differences in Tsumrequirements can be as high as 8°C at G5 (1200 m),

corresponding to a start of leaf unfolding 5 days earlier than at G0. Local adaptation allows F.sylvatica to expand at low elevation and to better survive at mid elevation.

Accounting for ecological and genetic processes changes species

distribution predictions: adaptation of Mediterranean forests to climate

change as a model

Introduction:Bioclimatic niche models predict drastic changes in the geographical distribution of forest species habitats by the end of the 21stcentury. However, these models rarely account for management and the dynamics of the forest response to climate change.Recent interdisciplinary research in diversity-rich Mediterranean forests shows how demographic and evolutionary processeschange local forest structure and composition. Integrating knowledge of these multiple processes into a comprehensivemodeling approach is necessary to understand how species will track their habitats under changing environmental conditions.

Effects of silvicultural regimes on forest resilience: An experimental study in Cedrus atlantica plantations

INRA PROVENCE-ALPES-COTE D’AZUR – UR629 URFM Ecologie des Forêts Méditerranéennes

Discussion and conclusions:Migration, because it is constrained, limits the ability of species to track their optimal habitat when the velocity of climate change is too high. Phenotypic plasticity and geneticadaptation, on the other hand, can occur rapidly and facilitate local persistence when habitats become sub-optimal. However, in the Mediterranean, disturbances such as forestfire and insect outbreaks are expected to rise to more frequent and severe levels by the end of the 21st century. These new disturbance regimes may result in demographic,evolutionary and functional tipping points where mortality becomes too massive and reproduction too limited for tree populations to adapt and survive. These processes need tobe better understood and further integrated for species distribution models to become more realistic, particularly at the spatial scale of management and forestry practice.

Bibliography: Fady & Conord (Div Distr) 2010, Fallour-Rubio et al. (JEB) 2009, Guillemot et al. (AFSc) 2015, Lefèvre et al. (AFSc) 2013, Oddou-Muratorio & Davi (Evol Appl) 2014

Key processes considered:• Demographic: Competition (density and

spacing) and migration (dispersal,recruitment);

• Evolutionary: Gene flow and drift, geneticadaptation and phenotypic plasticity.

1100 16001300 15001200

Altitude (m)

+ 0 °C

+ 2 °C

+ 3.5 °C

+ 6 °C

- 30 %

No change in range

- 40 % range reduction

Extinction

1400

Phenotypic plasticity is theprocess by which individualsmodify their phenotype as aresponse to environmentalchanges. The plastic response ofannual radial growth (RGI) tosummer precipitation (MJJA) inCedrus atlantica varies with age,environment and genotype. In thispopulation, plasticity evolvedacross three generations beyondage effects, facilitating adaptation.

Left: Aerial photograph of the experimental site and ground pictures of thecontrol plot and the most heavily thinned plot (2005).Center: Evolution of the stand basal area of the different plots.Right: The predicted growth response to annual climate (1990-2010) variedsignificantly under contrasted stand basal area (SBA) silvicultural treatments. Ayear was considered positive if its predicted growth response to climate at SBA= 55 m².ha-1 (average of the control plot) was higher than the average, negativeotherwise. During negative years, higher density stands had a significantlylower growth than stands where thinning had been substantial. The effect ofstand density was non significant for positive years.

Evolution of the range of Abies alba in Mont Ventoux(South-eastern France): A simulation study

Dynamics of local adaptation and genetic diversity under selection in a heterogeneous landscape: A simulation study

Effect of climate selection on budburst date in Fagus sylvatica: A simulation study

Changes in phenotypic plasticity across three cohorts in a Cedrus atlantica forest in south-eastern France

B. Fady, A. Amm, F. Courbet, Ph. Cubry, H. Davi, J. Guillemot, F. Lefèvre, S. Oddou-

Muratorio, C. Pichot, E. Rigolot

Contact: bruno.fady@avignon.inra.fr