Trait evolution in topical rubber (Hevea brasiliensis) trees is related to dry season intensity

1. Drought shapes the distribution and survival of trees even in tropical wet forests, and the wood and leaf trait spectra are used to understand drought adaptations. However, trait variation may result from ontogenetic adjustment or be related to tree size, and not reflect evolutionary adaptations. 2. Intraspecific variation in adaptations to drought can be an important factor in a species’ distribution and response to climate change, but excluding potentially confounding factors and proving adaptive evolution is challenging. Provenance trials can identify hereditary variability. 3. We analysed wood and leaf traits in rubber (Hevea brasiliensis) tree clones from 15 locations in the Amazon basin that were planted in northern Thailand, controlled for tree size, tested for genetic relatedness and the phylogenetic signal in traits, and compared trait variations with the climate at the location of origin. 4. Correlations between traits and tree size were low. Intra-specific trait variatio...