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 (P_ST–F_ST 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. P_ST–F_ST 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.

预计遗传漂变和发散选择都是斑块生境中种群分化的驱动因素，但这些力量作用于自然种群以塑造特征的程度受到物种生态特征的强烈影响。在这项研究中，我们推断了Pitcairnia lanuginosa的基因组结构，这是一种分布广泛的多年生草本植物，分布不均。我们对巴西塞拉多和安第斯中部永加斯的种群进行了抽样，并使用双酶切限制性位点相关的 DNA 测序发现了 SNP 标记并对其进行了基因分型。此外，我们分析了从普通花园实验中获得的生态生理特征，并比较了表型和遗传差异的模式（P _ST - F _ST比较）在来自塞拉多的人口子集中。我们的分子分析结果表明遗传多样性极低和显着的种群分化，支持遗传漂变的主要作用。至少有两种不同的方法将大约 0.3% 的基因分型 SNP 标记为分化异常值，并且贝叶斯广义线性混合模型揭示了环境隔离的特征，以及 Cerrado 种群中高分化异常值 SNP 的距离隔离。P _ST – F _ST比较表明，与耐旱性相关的两个生态生理特征存在不同的选择。我们发现这些特征在人群中有所不同，尽管没有任何特定的宏观空间模式，这表明当地适应了微生境的差异。我们的研究表明，选择可能是一种相关的力量，特别是对于涉及干旱胁迫的性状，即使对于经历强烈漂移的种群也是如此，这提高了我们对作用于非连续分布物种的生态进化过程的认识。