Data from: Genomic divergence across ecological gradients in the Central African rainforest songbird (Andropadus virens)

The little greenbul, a common rainforest passerine from sub-Saharan
Africa, has been the subject of long-term evolutionary studies to
understand the mechanisms leading to rainforest speciation. Previous
research found morphological and behavioural divergence across
rainforest–savannah transition zones (ecotones), and a pattern of
divergence with gene flow suggesting divergent natural selection has
contributed to adaptive divergence and ecotones could be important areas
for rainforests speciation. Recent advances in genomics and environmental
modelling make it possible to examine patterns of genetic divergence in a
more comprehensive fashion. To assess the extent to which natural
selection may drive patterns of differentiation, here we investigate
patterns of genomic differentiation among populations across environmental
gradients and regions. We find compelling evidence that individuals form
discrete genetic clusters corresponding to distinctive environmental
characteristics and habitat types. Pairwise FST between populations in
different habitats is significantly higher than within habitats, and this
differentiation is greater than what is expected from geographic distance
alone. Moreover, we identified 140 SNPs that showed extreme
differentiation among populations through a genomewide selection scan.
These outliers were significantly enriched in exonic and coding regions,
suggesting their functional importance. Environmental association analysis
of SNP variation indicates that several environmental variables, including
temperature and elevation, play important roles in driving the pattern of
genomic diversification. Results lend important new genomic evidence for
environmental gradients being important in population differentiation.