Understanding local adaptation through trade-offs among life history and ecophysiological traits in Aleppo pine (Pinus halepensis Mill.). Jose Climent 1,4 , Rafael Zas 2 , Jordi Voltas 3 , Maria Regina Chambel 1 , Luis Sampedro 2 , Juan Pedro Ferrio 3 1 Forest Research Centre-INIA (Madrid, Spain), 2 Misión Biológica de Galicia-CSIC (Pontevedra, Spain) 3 Dept. Crop and Forest Sciences. University of Lleida (Lleida, Spain) 4 Sustainable Forest Research Institute UVa-INIA Instituto Universitario de Investigación GESTIÓN FORESTAL SOSTENIBLE Universidad de Valladolid-INIA Instituto Universitario de Investigación GESTIÓN FORESTAL SOSTENIBLE Universidad de Valladolid-INIA BACKGROUND OBJECTIVES Here we performed a preliminary search for negative genetic correlations between life history and ecophysiological traits and the possible role of those trade-offs in the geographical structure of phenotypic variation within the species. • As any other living entity, forest trees must optimize resource investment to growth, reproduction and maintenance, but investment in one function may occur at the expense of other functions, resulting in trade-offs that limit maximization of all processes. • Global Change is imposing new challenges to Mediterranean forests, in particular owing to the combination of abiotic and biotic stressors such as drought, wildfires and epidemic outbreaks of pests and pathogens. • Mediterranean pine populations are expected to harbor a valuable adaptive genetic diversity for facing these challenges, already shaping the populations since long ago, but little is known about how populations will respond to multiple challenges, and about the correlated responses to a single stressor in other life history traits. • 19 provenances (numbers) covering a wide range of ecological conditions • Common garden in Castellón (East Spain), trees aged 13 structure of phenotypic variation within the species. METHODS • Common garden experiment with 19 range-wide provenances. • We measured: 1. A set of life-history traits related to i. growth and maintenance ii. reproduction iii. constitutive and induced defenses 2. A set of traits related to water and carbon acquisition and storage (Iberian and Balearic populations) iv. Carbon and oxygen isotopic composition v. Starch content in spring and autumn vi. Percentage of water extracted from upper and lower soil layers and from groundwater in summer through isotopic analysis of xylem water • Mixed models were used to obtain population means to perform a Principal 1.i Growth and maintenance traits Height Breast height diameter Bark thickness and bark diametric proportion Component Analysis and linear regressions between traits among populations. (1.ii) Reproductive traits Total female cones and last cohort female cones Percentage of serotinous cones (2) water and carbon acquisition and storage Cryogenic distillation of xylem water ( 18 O y 2 H) from cores Patterns of soil water extraction, water-use efficiency and reserves acquisition dynamics RESULTS (1.iii) Defense traits: bio-assay Constitutive resin flow Inducibility of resin flow after application of methil-jasmonate 11 21 92 101 105 11 1 131 142 15 2 154 157 172 173 182 185 211 214 231 241 -3 -2 -1 0 1 2 3 4 5 Factor 2: 31.55% Defensive Competitive -0.5 0.0 0.5 1.0 Factor 2 : 31.55% Constitutive resin Induced resin Dbh Bark thickness Height Bark proportion 1.4 1.6 1.8 2.0 2.2 2.4 450 550 650 750 850 Spring starch (%) Height (cm) 0 5 10 15 20 25 30 70.0 80.0 90.0 100.0 110.0 120.0 130.0 140.0 Contribution of upper soil water (%) Dbh (mm) 27 32 37 r soil water (%) PCA between population means for life history traits The position of the three groups of variables confirms the trade-offs predicted by life-history theory Inducibility of resin flow was little correlated with constitutive resin flow, and correlated with serotiny and reproduction (Bark proportion is represented as a supplementary variable but not influencing the axes calculations) Active -4 -3 -2 -1 0 1 2 3 4 5 6 7 Factor 1: 43.06% -5 -4 Reproductive Population differentiation based on life history trait correlations While several populations show a low differentiation (central group), there are some geographically consistent extreme groups: • The two Greek populations (211 and 214) with an extreme prevalence of vegetative growth • Iberian north-eastern and Balearic populations (11, 21, 92, 182) with a marked prevalence of constitutive defenses and high bark proportion • A southern Iberian (172) and the Tunisian (241) populations with an extreme prevalence of early reproduction and serotiny, linked to high plasticity for inducing chemical defenses Active Suppl. -1.0 -0.5 0.0 0.5 1.0 Factor 1 : 43.06% -1.0 Serotiny Total female cones Last cohort cones 7 12 17 22 0.30 0.35 0.40 0.45 0.50 Contribution of lower Bark diametral proportion Life history traits vs. water and carbon dynamics Negative correlation between height and non-structural carbon reserves in spring (R = -0.76***) Positive correlations between breast height diameter and contribution of upper soil water (R = 0.60*) and between bark proportion and contribution of lower soil water (R = 0.60*) Negative correlation between water use efficiency and contribution of upper soil water (previous studies) This research is part of projects AGL 2012-40151-C03 (sub-projects 01. 02 and 03) funded by Spanish Ministry of Economy and Competiveness Many thanks to Luis Santos del Blanco for help in data analysis Data used in this study is part of the Spanish Network of Genetic Trials (GENFORED). We thank all persons and institutions linked to the establishment and measurement of the field trials and to the maintenance of the network CONCLUSIONS Trade-offs between growth+maintenance, reproduction and constitutive defenses were rather evident among population of Aleppo pine. • The two Greek populations share the highest growth rates at the expenses of reducing investment to reproduction and defense. • Populations exhibiting early reproduction showed an inducible defensive strategy, rather than investing in constitutive defenses. • Cone serotiny correlated positively with female fecundity (i.e. there is no evidence for a trade-off between producing many cones and keeping them closed) High vegetative growth was associated to low levels of reserve carbohydrates, consistent with the trade-offs with defense and reproduction. Higher growth is also associated to higher contribution of upper soil water, at the expenses of lower drought resistance. 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