Disentangling local adaptation drivers in the Andean Nothofagus pumilio

SEKELEY JILL; MARÍA GABRIELA MATTERA; KATRIN HEER; MARIA VERONICA ARANA; PASTORINO, MARIO J.; LARS OPGENOORTH; MARCHELLI, PAULA; CAROLINA SOLIANI

Conferencia; Evoltree Conference 2021; 2021

Disentangling the effects of individual environmental factors is important for determining the driving factors of local adaptation. However, natural forests inhabit landscapes with overlapping and interacting environmental gradients, which makes this endeavor notoriously difficult in situ. The cold-adapted Nothofagus pumilio forests present an ideal study system because they stretch over a 2000-kilometer range, from the high-altitude subtropics (35°S) to sea level at the southernmost tip of Tierra del Fuego (56°S). This species inhabits the southern Andes mountains, which run almost perfectly North to South and contain clear precipitation, day-length, and temperature gradients, which are three of the most biologically important environmental gradients. To assess in situ adaptation, we sampled 500 N. pumilio adults along these gradients using a paired-site sampling design. A pair contained two sites that were close enough to share an evolutionary history but far enough apart in elevation to experience different temperature conditions. Using a set of ~50,000 SNPs from candidate genes and the CHELSA dataset of global climate parameters, we performed an association genetic analysis to discover genes that may be under selection. We investigated population structure (e.g. ADMIXTURE), possible SNP outliers (pcadapt, outFLANK), and gene–environment associations (LFMM2). These results will fuel further downstream analyses of local adaptation including phenotype–environment associations and demographic history inference.