Continuity of evolutionary processes across hierarchy and scale is by no means a given, and discordance may be expected, informative, and critical in understanding the scale and reach of different evolutionary mechanisms. For example, trait variation and covariation are known to impact the response of populations to natural selection on microevolutionary time scales, but their role in shaping long-term macroevolutionary divergence is still unclear. As heritable morphological variation is the raw material on which natural selection acts, understanding its structure and lability can directly inform the extent to which microevolutionary forces may extend into macroevolutionary time. Over the course of this dissertation, my work has focused on addressing questions central to both micro- and macroevolutionary paradigms, by exploiting the unique biology of Neotropical army ants with modern scientific methods. Through investigating the cross-section of genomics, geography, and developmental plasticity in Neotropical army ants, my work has aimed at bridging our understanding of evolutionary processes across broad spatial and temporal scales.