Patterns of phenotypic plasticity among populations of three Mediterranean pine species and implications for evolutionary responses to climate change

AimUnder rapid environmental change, phenotypic plasticity, if adaptive, could increase the odds for organisms to persist. Environmental variation over time is an important source of phenotypic plasticity. Likewise, phenotypic plasticity can vary with age in many organisms. However, little is known on phenotypic plasticity variation across species ranges. Our aims are: (i) to assess whether populations phenotypic plasticity is related to the inter-annual climate variation under which populations have evolved during the last century; (ii) to compare phenotypic plasticity among developmental classes; and (iii) to predict phenotypic plasticity across species ranges.\n\nLocationEurope and North-Africa.\n\nTime period1901-2014.\n\nMajor taxa studiedPinus nigra, P. pinaster and P. pinea.\n\nMethodsWe used 372 646 individual tree height measurements at three developmental classes from a wide network of 38 common gardens in Europe and North Africa with provenances covering the distribution range of the species. With this data, we: i) build linear mixed-effect models of tree height as a function of tree age, population and climate; ii) estimate populations reaction norms from the fitted models; iii) calculate populations phenotypic plasticity indexes; iv) build models of populations phenotypic plasticity indexes as a function of inter-annual climate variation during the last century.\n\nResultsWe found that i) most populations that have evolved under high inter-annual climate variation, in either maximum or minimum values in temperature or precipitation, exhibited high values of plasticity in tree height; ii) phenotypic plasticity for tree height was higher in young trees than in older ones, iii) phenotypic plasticity did not follow any particular geographical pattern across species ranges.\n\nMain conclusionsPhenotypic plasticity across the three Mediterranean pines ranges is related with the climate variation experienced over time and calls into question whether this plasticity could be adaptive and hence beneficial to cope with climate change in the short-term.