Genome-wide association and landscape genomics identifies patterns of
environmental adaptation in Araucaria angustifolia
Abstract
Araucaria angustifolia has high economic, social, and ecological
importance in Brazil, although it is critically threatened with
extinction. To understand araucaria’s adaptation, we used a genome-wide
association studies (GWAS) to identify markers with signatures of
selection associating genomic variation to phenotypic and climatic
variables. We also used landscape genomics to identify geographic
regions at the highest risk of extinction for the species due to climate
change. We used phenotypic and genotypic data of 859 adult trees from a
provenance-progeny trial (15 populations), 1,304 SNPs, climatic
variables, and growth traits. The GWAS analyses were performed using a
general linear model, the Wald test, and a Bayesian method based on
population divergence. BLAST techniques were used to gather information
about the selected markers. We estimated the proportion of variance
explained by regression of genomic data against phenotypic and climatic
variables. To estimate vulnerability to climate change, we used the
gradient forests. We identified outlier SNPs associated with the
climatic and phenotypic traits. Considering the climatic features as
drivers of araucaria adaptation, we see that precipitation in the dry
season is the leading and most predictable adaptation trait for
araucaria. Genomic offset (Goff) for the most optimistic scenario shows
that the main critical area is the transition between the tropical and
temperate climates in Brazil. In Goff’s most pessimistic scenario, the
entire temperate region presents a change in allele turnover. In this
context, we propose strategies like assisted migration and targeted
reforestation management to accelerate the adaptation of araucaria to
the predicted scenarios.