RAD-seq data from: Evidence of local adaptation despite strong drift in a Neotropical patchily distributed bromeliad

Both genetic drift and divergent selection are predicted to be drivers of
population differentiation across patchy habitats, but the extent to which
these forces act on natural populations to shape traits is strongly
affected by species' ecological features. In this study, we infer the
genomic structure of Pitcairnia lanuginosa, a widespread herbaceous
perennial plant with a patchy distribution. We sampled populations in the
Brazilian Cerrado and the Central Andean Yungas and discovered and
genotyped SNP markers using double-digest restriction-site associated DNA
sequencing. In addition, we analyzed ecophysiological traits obtained from
a common garden experiment and compared patterns of phenotypic and genetic
divergence (PST-FST comparisons) in a subset of populations from the
Cerrado. Our results from molecular analyses pointed to extremely low
genetic diversity and a remarkable population differentiation, supporting
a major role of genetic drift. Approximately 0.3% of genotyped SNPs were
flagged as differentiation outliers by at least two distinct methods, and
Bayesian generalized linear mixed models revealed a signature of isolation
by environment in addition to isolation by distance for
high-differentiation outlier SNPs among the Cerrado populations. PST-FST
comparisons suggested divergent selection on two ecophysiological traits
linked to drought tolerance. We showed that these traits vary among
populations, although without any particular macro-spatial pattern,
suggesting local adaptation to differences in micro-habitats. Our study
shows that selection might be a relevant force, particularly for traits
involved in drought stress, even for populations experiencing strong
drift, which improves our knowledge on eco-evolutionary processes acting
on non-continuously distributed species.