Data from: 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 variation was
similar to relationships in published among-species comparisons and
correlations among wood traits and correlations among leaf traits were
stronger than between wood and leaf traits. Genotype explained 30 – 70% of
the trait variation, and traits differed in how much of this variation was
controlled by location or the relatedness among clones. 5. There was no
correlation with mean temperature or total annual rainfall. However,
rainfall in the driest quarter (19 – 199 mm) was strongly related to leaf
mass per area, carbon isotopic composition and area-based nitrogen
content(r2 = 0.54 - 0.70) and weaker to wood traits (vessel density and
vessel lumen fraction). Trees from locations with a stronger dry season
also had higher growth rates in Thailand. 6. All traits correlating with
climate showed a significant phylogenetic signal. We found no evidence of
increased drought tolerance, but the trait spectrum and higher growth in
trees from drier locations suggests that deciduous rubber trees have
adapted via drought avoidance rather than tolerance. Our study also
underlines the importance of looking at a suite of traits rather than
individual ones to understand adaptive strategies.