Changes in mitochondrial function parallel life history transitions between flight and reproduction in wing polymorphic field crickets

Abstract

Mitochondria serve as critical producers of both cellular energy and metabolic precursors for biosynthesis required for organismal growth, activity, somatic maintenance, and reproduction. Consequently, variation in mitochondrial function is commonly associated with variation in life histories both within and across species. For instance, flight-capable, long-winged crickets have mitochondria with larger bioenergetic capacities than flightless, short-winged crickets investing in early lifetime fecundity instead of flight. However, we do not know whether differences in mitochondrial function associated with life history are fixed or result from flexible changes in metabolism throughout the life cycle. We measured mitochondrial function of fat body tissue across early adulthood of long-winged and short-winged crickets from two species of wing-polymorphic field crickets (Gryllus firmus and Gryllus lineaticeps). Fat body is a multifunctional organ that supports both flight and reproduction in insects. Consistent with flexibility in mitochondrial function specific for alternative life histories, the capacity for oxidative phosphorylation increases in mitochondria throughout early adulthood in the fat body of long-winged but not short-winged crickets. Furthermore, fat body mitochondrial oxidative phosphorylation capacities declined rapidly when long-wing crickets degraded their flight muscles and initiated large-scale oogenesis. This finding suggests that shifts in tissue function require a concurrent shift in mitochondrial function and that tissue-specific functional constraints may underpin the flight-oogenesis trade-off. In conclusion, changes in mitochondrial bioenergetics form a component of alternative life histories, indicating that mitochondrial function is dynamic and set to a level that matches current and future energy demands and biosynthetic requirements of life history.

Keywords: bioenergetics; fat body; insect; life history trade-off; mitochondria.