Abstract
Complex environments, characterized by co-varying factors (e.g. temperature and food availability) may cause animals to invest resources differentially into fitness-related traits. Thus, experiments manipulating multiple environmental factors concurrently provide valuable insight into the role of the environment in shaping not only important traits (e.g. dispersal capacity or reproduction), but also trait–trait interactions (e.g. trade-offs between traits). We used a multi-factorial design to manipulate variation in temperature (constant 28 °C vs. 28 ± 5 °C daily cycle) and food availability (unlimited vs. intermittent access) throughout development in the sand field cricket (Gryllus firmus). Using a univariate approach, we found that temperature variability and unlimited food availability promoted survival, development, growth, body size and/or reproductive investment. Using principal components as indices of resource allocation strategy, we found that temperature variability and unlimited food reduced investment into flight capacity in females. Thus, we detected a sex-specific trade-off between flight and other life-history traits that was developmentally plastic in response to variation in temperature and food availability. We develop an experimental and statistical framework to reveal shifts in correlative patterns of investment into different life-history traits. This approach can be applied to a range of biological systems to investigate how environmental complexity influences traits and trait trade-offs.
Food availability and parasite infection influence the correlated responses of life history traits to selection for age at pupation in the mosquito Aedes aegypti
