Genomic signatures of ecological divergence between savanna and forest populations of a Neotropical tree.

This article focuses on the genomic divergence and ecological differentiation between two ecotypes of the South American tree Plathymenia reticulata, one from the Cerrado savanna and the other from the Atlantic Forest, which form a hybrid zone in their ecotonal contact area. Using double-digest restriction site-associated DNA sequencing (ddRADseq), the study found high genetic divergence between the ecotypes, with only early-generation hybrids present in the hybrid zone, indicating partial reproductive isolation and supporting their recognition as distinct evolutionary lineages. Genetic divergence was significantly associated with environmental factors such as soil composition and climate, and outlier loci under divergent selection were linked to stress responses, plant development, and reproduction. The findings suggest that ecological divergence drives speciation processes in these lineages and have implications for conservation, including the recommendation to reassess the forest ecotype's vulnerable status and to manage the ecotypes as separate units.