110.2 Saturday, Jan. 7 Nutritional Constraints in the Evolution of Cognition: effects of host shifts on neural investment in butterflies SNELL-ROOD, EC*; WHITE, WA; ESPESET, A; KENZIE, SA; University of Minnesota; University of Minnesota; University of Minnesota; University of Minnesota firstname.lastname@example.org
Understanding why organisms vary in cognition is key to predicting how individuals will respond to changing and novel environments. Diet has been hypothesized to play a role in constraining the evolution of large, costly brains. This work provides the first systematic test of this idea. Butterflies were used as a system because nutrient availability is easily manipulated in artificial diets and nutrition of larval diets varies widely across species. We focused on both the availability of limiting macronutrients (phosphorus, nitrogen) and micronutrients (potassium, sodium) in diets that varied within and across species. Given that over 70% of the butterfly brain is dedicated to visual processing, we use relative eye size as a proxy for neural investment. We found that across 28 species of butterflies, evolutionary shifts in the availability of phosphorus and electrolytes in host plants influenced relative eye size and the density of ommatidia (the units of the compound eye). We have additionally performed a series of artificial diet manipulations within cabbage white butterflies (Pieris rapae) to determine the contribution of development to variation in relative eye size and to test evolutionary changes in dietary requirements across populations that differ in learning ability. Overall, this work suggests that nutrition may indeed constrain the evolution of neural investment, at least in the short term.