Natural selection and neutral evolutionary processes contribute to genetic divergence in leaf traits across a precipitation gradient in the tropical oak Quercus oleoides

The impacts of drought are expanding worldwide as a consequence of climate change. However, there is still little knowledge of how species respond to long-term selection in seasonally-dry ecosystems. In this study, we used QST-FST comparisons to investigate (i) the role of natural selection on population genetic differentiation for a set of functional traits related to drought resistance in the seasonally-dry tropical oak Quercus oleoides and (ii) the influence of water availability at the site of population origin and in experimental treatments on patterns of trait divergence. We conducted a thorough phenotypic characterization of 1896 seedlings from ten populations growing in field and greenhouse common gardens under replicated watering treatments. We also genotyped 222 individuals from the same set of populations using eleven nuclear microsatellites. The data sets include all of the raw data used in the analyses include nuclear microsatellites from populations examined in the field common garden, phenotypic data from a field common garden, nuclear microsatellites from populations examined in a greenhouse experiment, and phenotypic data from a field common garden.