Figure 2.

Trait–climate associations between quantitative genetic traits and bioclimate variables generated using Geographical Information Systems (modified from Nakazato et al. 2008). As described in Nakazato et al. (2008), 10 populations of Solanum pimpinellifolium were assessed for quantitative genetic variation in a common garden environment and under drought manipulation. Top panel (A) shows the relationship between native mean annual precipitation (mm) experienced by each population, and the average seedling root length when germinated under common garden conditions. Bottom panel (B) shows the relationship between native annual precipitation and the number of days to wilting in juvenile (prereproductive) plants from each population, once water was withheld. Both significant relationships suggest that traits associated with drought responses are preferentially found in populations with low native rainfall, consistent with natural selection for these population differences.