No abstract

32Our understanding of how the design of peripheral sensory structures is coupled with neural 33 processing capacity to adaptively support division of labor is limited. Workers of the remarkably 34 polymorphic fungus-growing ant Atta cephalotes are behaviorally specialized by size: the 35 smallest workers (minims) tend fungi in dark subterranean chambers while larger workers 36 perform tasks mainly outside the nest. These strong differences in worksite light conditions are 37 predicted to influence sensory and processing requirements for vision. We found that eye 38 structure and visual neuropils have been be selected to maximize task performance according to 39 light availability. Minim eyes had few ommatidia, large interommatidial angles and eye 40 parameter values, suggesting selection for visual sensitivity over acuity. Large workers had 41 larger eyes with disproportionally more and larger ommatidia, and smaller interommatidial 42 angles and eye parameter values, reflecting peripheral sensory adaptation to ambient rainforest 43 light. Additionally, optic lobe and mushroom body collar volumes were disproportionately small 44 in minims, and within the optic lobe, lamina and lobula relative volumes increased with worker 45 size whereas the medulla decreased. Visual system phenotypes thus correspond to task 46 specializations in dark or light environments and reflect a functional neuroplasticity 47 underpinning division of labor in this socially complex agricultural ant. 48 49