Intraspecific trait variation plays a fundamental role in shaping plant ecological strategies and population responses to environmental gradients. In this study, we examined coordinated variation in leaf and seed traits across four populations of the coastal shrub Corema album distributed along a humid to semi-arid gradient in Portugal. Using a multivariate trait framework, we found strong evidence of a resource acquisition-conservation trade-off that aligns with macroclimatic water availability: populations from wetter sites displayed more acquisitive traits (e.g., high leaf nitrogen, rapid stem growth), while drier populations exhibited more conservative traits (e.g., higher delta C-1(3) and larger seed volume). These trait patterns reflect broad-scale environmental filtering, consistent with the plant economics spectrum. However, we also detected significant trait differentiation among arid populations with similar climate, suggesting that microhabitat variation-such as edaphic or hydrological conditions-further shapes interpopulation differences and functional strategies at finer spatial scales. Notably, intra-population trait variability did not correlate with genetic diversity, indicating that intraspecific phenotypic variation or selection on existing genetic variation, rather than non-selective evolutionary processes, is driving observed patterns. Our findings highlight how both macroclimatic gradients and local environmental heterogeneity interact to shape intraspecific trait covariation and variability. This work reinforces the need to consider multi-scale environmental drivers and coordinated trait syndromes in the study of species ecological strategies and their evolutionary implications.