Life history traits such as longevity, dispersal and total reproductive output are key organismal adaptations. Many life history traits are negatively coupled with each other because nutrients allocated towards one trait (e.g. egg production) are not available for another trait (e.g. production of lipid fuel for dispersal). The magnitude of trade-offs can be strongly influenced by the amount and quality of nutrients available to an organism, but currently little is known about how nutrient inputs affect life history trade-offs. Here this issue is investigated using a wing-polymorphic cricket, Gryllus firmus. This cricket exists as one of two genetically-specified forms, one adapted for flight (dispersal) at the expense of egg production, the other adapted to maximize reproduction at the expense of dispersal (it lacks flight muscle). Using a range of well-defined diets that differ in their protein-carbohydrate composition (and total caloric content), a comparison will be made that reveals how these two contrasting phenotypes differentially extract, interconvert, and eliminate protein and carbohydrate demanded by their specific life history. Specifically, this study will measure consumption and assimilation of protein and carbohydrates into body tissues, document how these two nutrients are allocated to flight and reproduction organs, and use radiotracer and enzymological studies of biochemical pathways to study interconversion and metabolic elimination of these two nutrients. An important focus will be identifying the physiological mechanisms that allow a particular phenotype to acquire/produce the biomolecules it needs (for its life history) in a constantly shifting nutritional environment. Results will be applicable to a wide range of organisms, including life history traits (e.g. longevity) in humans. This project also has a significant instructional component, including the training of a postdoctoral associate, research opportunities for undergraduate students, and the development of workshops for secondary school educators which provides novel approaches to teaching basic principles of evolution.
