Supplementary Material for: Neuroanatomical and Morphological Trait Clusters in the Ant Genus <b><i>Pheidole:</i></b> Evidence for Modularity and Integration in Brain Structure

A central question in brain evolution concerns how selection has structured neuromorphological variation to generate adaptive behavior. In social insects, brain structures differ between reproductive and sterile castes, and worker behavioral specializations related to morphology, age, and ecology are associated with intra- and interspecific variation in investment in functionally different brain compartments. Workers in the hyperdiverse ant genus <i>Pheidole </i>are morphologically and behaviorally differentiated into minor and major subcastes that exhibit distinct species-typical patterns of brain compartment size variation. We examined integration and modularity in brain organization and its developmental patterning in three ecotypical <i>Pheidole</i> species by analyzing intra- and interspecific morphological and neuroanatomical covariation. Our results identified two trait clusters, the first involving olfaction and social information processing and the second composed of brain regions regulating nonolfactory sensorimotor functions. Patterns of size covariation between brain compartments within subcastes were consistent with levels of behavioral differentiation between minor and major workers. Globally, brains of mature workers were more heterogeneous than brains of newly eclosed workers, suggesting diversified developmental trajectories underscore species- and subcaste-typical brain organization. Variation in brain structure associated with the striking worker polyphenism in our sample of <i>Pheidole</i> appears to originate from initially differentiated brain templates that further diverge through species- and subcaste-specific processes of maturation and behavioral development

Nonrandom search geometry in subterranean termites

[Extract] Studies of the organization of search in ants suggest that individual and colonylevel patterns are related to foraging ecology and may be adaptive [1, 2]. The organization of search in termites has received far less attention, in part because of their cryptic, subterranean foraging habits. Search in subterranean termites involves the construction of a gallery system, a series of branching tunnels in the soil that brings termites into contact with food. The organization of the gallery system might reflect the efficiency of colony search. In this paper we describe the nonrandom colony- level search pattern of the subterranean termite Reticulitermes ftavipes (Kollar), and suggest that it may be organized to minimize search redundancy