1.Changes in resource availability, functional demands, hormonal regulation and developmental constraints can promote differences in the expression of leaf traits during plant development and foster changes in the targets of natural selection. As a consequence, the pattern and magnitude of covariation among traits, and therefore their phenotypic integration and modularity are equally expected to change throughout ontogeny. However, these changes have not been described yet. 2.We measured leaf economic, defensive and morphological traits in plants of Turnera velutina and estimated the magnitude and pattern of foliar integration and modularity for juvenile and reproductive individuals. In addition, we assessed the relationship between plant biomass and foliar integration within and among ontogenetic stages. 3.Both the pattern and magnitude of foliar integration changed across plant ontogeny. Foliar integration was lower in juvenile than in reproductive plants, and the pattern of phenotypic integration and modularity was different between ontogenetic stages: whereas leaves from juvenile plants showed two functional modules related to plant defence and leaf economy, traits from reproductive plants had greater interconnectivity and hence lower modularity. 4.The relationship between plant biomass and foliar integration was negative within each ontogenetic stage but positive between ontogenetic stages, suggesting that processes intrinsic to plant development influenced the magnitude of foliar integration to a greater extent than plant size. 5.Our findings indicate that plants can change the patterns of covariation among leaf traits during their development. Whereas a lower foliar integration in juvenile plants could allow for greater lability to explore a multi-trait phenotypic space, canalization of leaf attributes along ontogeny should promote greater phenotypic integration, constraining the number of multi-trait combinations that plants can express. Hence, we suggest that ontogenetic changes in foliar integration allow plants to deal with changing selective dynamics and physiological priorities along their development.

Because pollinators are unable to directly assess the amount of rewards offered by flowers, they rely on the information provided by advertising floral traits. Thus, having a lower intra-individual correlation between signal and reward (signal accuracy) than other plants in the population provides the opportunity to reduce investment in rewards and cheat pollinators. However, pollinators' cognitive capacities can impose a limit to the evolution of this plant cheating strategy if they can punish those plants with low signal accuracy. In this study we examined the opportunity for cheating in the perennial weed Turnera ulmifolia L. evaluating the selective value of signal accuracy, floral display and reward production in a natural population. We found that plant reproductive success was positively related to signal accuracy and floral display, but not to nectar production. The intensity of selection on floral display was more than three times higher than on signal accuracy. The pattern of selection indicated that pollinators can select for signal accuracy provided by plants, and suggest that learning abilities of pollinators can limit the evolution of deceptive strategies in T. ulmifolia.