Phenotypic plasticity is broadly adaptive across an elevation gradient in the Cutleaf Monkeyflower

Abstract

O_LIPhenotypic plasticity is a key mechanism by which organisms can cope with environmental heterogeneity, but its evolutionary consequences depend on how plastic responses align with the broader adaptive landscape. C_LIO_LIWe tested whether plasticity in leaf shape alongside other traits is associated with differential fitness across an elevational gradient in Mimulus laciniatus, an annual wildflower endemic to montane California. Using a reciprocal transplant experiment and recombinant inbred lines (RILs) previously phenotyped for plasticity in controlled conditions, we measured variation in survival and fecundity in native low- and high-elevation habitats. C_LIO_LIBased on previous work, we expected to find selection against leaf shape plasticity at low-elevation and selection for leaf shape plasticity in the high-elevation direction (increased leaf lobing under long-day conditions) at high-elevation. Interestingly, we found that RIL genotypes exhibiting high-elevation plasticity had the greatest survival to seed production at high-elevations, but that low-elevation plasticity (increased leaf lobing under short-day conditions) was associated with greater fecundity in both elevations. RILs with high-elevation plasticity also outperformed non-plastic genotypes at high-elevation. C_LIO_LIThis pattern suggests that plasticity is broadly beneficial across a species geographic range even if local variation in the direction of plasticity is not always adaptive. C_LI