Wet season environments drive local adaptation in the drought-sensitive
timber tree Dicorynia guianensis in French Guiana
Abstract
Climate change poses threats to biodiversity, particularly in tropical
rainforests. How tropical rainforest tree species will respond to
climate change is uncertain because their extent of local adaptation,
its drivers and genetic basis remain poorly known. Characterizing these
and the risks of maladaptation in future climates can inform on possible
responses and help design strategies for the conservation. This study
focuses on Dicorynia guianensis (Fabaceae), a widespread tree species in
French Guiana, known for its sensitivity to drought. We performed genome
resequencing on 87 individuals sampled in 11 sites across French Guiana
to investigate the genetic structure, diversity, the drivers and the
genetic basis of local adaptation. Genetic structure analysis identified
three distinct groups: western, inland, and eastern, with similar levels
of genetic diversity and distributed in areas with different
environmental conditions. Six methods applied to detect genomic
signatures of selection revealed region-specific selective sweeps and
overlap between SNPs identified through outlier analysis or
genome-environment association analyses. The most relevant environmental
drivers of selection were potential evapotranspiration of the wettest
quarter and precipitation of the coldest quarter, indicating that
environmental variables related to high rainfall during the wet season
are stronger drivers of local adaptation of D. guianensis than drought.
Sites located in inland French Guiana had higher risks of climatic
maladaptation than coastal sites. Our results contribute to the
understanding of local adaptation and risk of maladaptation in tropical
trees. They emphasize the need for area-specific approaches in managing
tropical tree under the pressures of climate change.