Meeting Abstract
Daily hormonal rhythms are an important part of organismal life-history adaptation, but little is known about how genetic variation in endocrine traits is linked to the organismal traits they regulate. Wing-polymorphic crickets, Gryllus firmus, have a well-characterized genetically-polymorphic circadian rhythm for juvenile hormone (JH), which is linked to a genetic polymorphism for flight capability. We tested the hypothesis that the morph-specific JH titer cycle is linked to metabolic preparation for flight by injecting 13C-labeled nutrient tracers into flight-capable and flightless crickets at five timepoints across the circadian cycle, and measured oxygen consumption, carbon dioxide production, and metabolite oxidation rates. Respiratory quotients were higher during the day and decreased at night in both morphs. In contrast, glucose oxidation rates were acyclic in flightless crickets, but decreased at night in the flight-capable morph. These patterns suggest that the JH titer cycle in flight-capable crickets is associated with a switch in the utilization of different metabolic fuels at different times in the circadian cycle, providing a link between the genetically-polymorphic hormonal rhythm and a key trait it may regulate.
