GenTree Upside Down: Local adaptation of Nothofagus pumilio along environmental gradients in the Andes

SEKELY, JILL; ARANA, M. VERÓNICA; DALLA SALDA, GUILLERMINA; HEER, KATRIN; MARCHELLI, PAULA; MARTINEZ MEIER, ALEJANDRO; MATTERA, GABRIELA; OPGENOORTH, LARS; PASTORINO, MARIO J; SCOTTI, IVAN; SOLIANI, CAROLINA

Avignon

Conferencia; Genetics to the rescue: managing forests sustainably in a changing world; 2020

Universidad de Avignon

Natural selection pressures vary in time and space. Local adaptation is the product of divergent selection based on such spatial variation, which creates populations that have higher relative fitness in their home environments. The Andes mountain range is an ideal location to study both the current extent and drivers of local adaptation. The geography of the Andes creates various environmental gradients, including a north-south temperature and photoperiod cline and a west-east precipitation gradient. Nothofagus pumilio is a common deciduous tree that inhabits the southern Andes between 36°S to 55°S latitude. This project?s overarching aim is to determine the current extent and bases of local adaptation in N. pumilio, i.e. to disentangle the interactions between genotype, phenotype, and environmental conditions. This project is an extension of the Europe-centric GenTree 2020 project, and will use similar rationale. We hypothesize that limited gene flow and steep day-length and precipitation gradients have created pronounced local adaptation. Furthermore, we hypothesize that individual trees have significantly different responses to stress events, and that this phenomenon is associated with genomic regions that are under different selection pressures. To test these hypotheses, we will first use a genome-wide association study to link genotypes with environmental variables at both the individual and population levels. To approximate growth responses to environment, we will use variation in annual increment within individual tree-ring series. This time series-based dendrophenotypic approach enables us to study individual responses to both long-term climate and short-term stress events, namely extreme climate events such as severe drought, El Niño-Southern Oscillation, and pest outbreaks, all of which are expected to become more unpredictable and extreme under climate change. To analyze the current patterns of local adaptation in N. pumilio, we employ a randomized paired study design, in which we sample nine pairs of sampling sites that are far enough apart to experience different environmental selection pressures but close enough to share a common evolutionary history. Additionally, we will sample two sites in xeric populations which will be analyzed with two mesic sites to represent the precipitation gradient. Finally, we intend to compare patterns of local adaptation among N. pumilio and the seven GenTree species, to determine whether similar selective pressures in South America and Europe have led to convergent evolution.