Meeting Abstract
My current research explores the divergence in metabolic plasticity in response to seasonal rearing conditions among migratory and non-migratory populations of monarch butterflies. The long migration that returns individuals to overwintering sites in Mexico is four generations removed from the individuals that migrated north during the spring and summer. This natural history predicts developmental plasticity for many aspects of flight physiology and energy allocation to enable long-distance migration in the context of a life-history strategy that requires conservation of energy to invest in reproduction after overwintering. Furthermore, not all populations migrate, allowing for population divergence in migration-associated traits. Using migratory (North American) and non-migratory (Costa Rican) populations of monarchs reared for two seasons under both non-migratory (summer) and migratory (fall) conditions, we tested the prediction that migratory populations have greater plasticity in metabolic performance in response to rearing conditions than do non-migratory populations. We find that Costa Rican populations have elevated resting metabolic rates in response to fall migratory rearing conditions. Under these same conditions, the Costa Rican population also has higher resting metabolic rates relative to the North American population. Together, these patterns indicate that North American, but not Costa Rican, populations can maintain metabolic homeostasis across seasonal rearing environments. We also find that the two populations have different metabolic scaling coefficients for their flight metabolic rate in response to fall migratory rearing conditions.
