Maternal Effects Generate Variation in Life History: Consequences of Egg Weight Plasticity in the Gypsy Moth

Abstract

Features of an individual's life history are the product of its genotypic background and environmental experience. For the gypsy moth, Lymantria dispar L., the earliest environmental experience comes via maternal nutrients supplied to the egg. To estimate the importance of maternal provisions to the expression of offspring life history in the gypsy moth, egg weights of siblings were measured 1 week before hatch in each of 18 families. Siblings representing the range of egg weights produced by each mother were reared individually under homogeneous conditions and monitored for time until hatch, larval development time and pupal weight. There was significant variation among families in each life-history trait for both sexes suggesting the presence of genetic variation. Life-history expression also had a strong maternal effect component. Based on partial correlation coefficients which control for familial differences in life-history expression, the following relationships were seen: when individuals came from larger eggs, they hatched earlier (both sexes), daughters finished the larval period faster, and became heavier pupae. Maternal effects generate phenotypic variation within a family. This may represent a bet-hedging strategy in response to the environment typically encountered by this species: an unpredictable one. Key-words: Bet-hedging, egg provisions, gypsy moth, Lyman tria dispar, life-history traits, maternal effects, plant-herbivore interactions