1 INTRODUCTION Abiotic stress is a major driver of plant phenotypic diversity (Lowry, 2012), acting to select locally adapted varieties with specific morphological, physiological, and phenological traits (Fumagalli et al., 2011; Hereford, 2009; Stebbins, 1952). Differences in such selective pressures over a continuously varying environment produce clines of genetic and phenotypic variation, reflecting the shifting costs and benefits of diverse biological strategies (Joswig et al., 2022).