26.6 Wednesday, Jan. 4 Direct and indirect selection on size and development in Manduca sexta KINGSOLVER, JG*; DIAMOND, SE; SEITER, S; HIGGINS, JK; UNC, Chapel Hill; UNC, Chapel Hill; UNC, Chapel Hill; UNC, Chapel Hill firstname.lastname@example.org
Adult size and development time are the outcomes of growth and differentiation throughout the life of an individual organism—its developmental trajectory. As a result, there will be both direct and indirect components of selection on body size and age during development. We used two field studies in experimental gardens to evaluate phenotypic selection on size and age across larval, pupal and adult stages in the tobacco hornworm, Manduca sexta. Rapid larval development was positively associated with survival to pupation and adulthood, in part because it allowed escape from larval parasitoids. Egg production was positively correlated with adult mass, but not with development time. Principal components analyses of size and age throughout development showed that adult size and development time were not negatively correlated, contrary to life history expectations. As a result, selection favoring larger adult size (via female reproduction) and selection favoring rapid larval development (via juvenile survival) act quite independently in this system. We discuss the physiological mechanisms that may underlie the independence of adult size and early larval development for holometabolous insects, and the implications for selection on body size and developmental trajectories.