Meeting Abstract
Animals are under selection to optimize several traits associated with fitness, such as reproduction, growth, and self-maintenance. However, a tradeoff among two traits often occurs wherein an animal invests into one trait at the expense of investment into another trait. Such two-trait tradeoffs may be fixed, but they may also be plastic in response to the environment (e.g., a tradeoff only occurs when food becomes less available) or due to investment into a third trait. We investigated these dynamics in female sand field crickets (Gryllus firmus), which exhibit a wing polymorphism that mediates a flight-fecundity tradeoff. During early adulthood, short-winged (SW) females prioritize egg production (fecundity) over locomotion or dispersal (flight) capability while long-winged (LW) females invest in flight musculature at the expense of fecundity. We used a 2 x 2 factorial design to manipulate food availability (unlimited or limited access to cat food) and investment into antioxidant defenses (repeated injection of the oxidative stressor, paraquat, or a sham injection) for SW and LW females during early adulthood. We measured the following traits: body size and condition (femur length and scaled mass index, respectively), and investment into fecundity (dry ovary mass) and flight (status of the dorso-longitudinal muscles). Preliminary results in LW females indicate that oxidative stress and food limitation shift the flight-fecundity tradeoff in different directions: oxidative stress reduces investment into flight musculature while food limitation reduces investment into ovary mass. Complete results from our study will inform the dynamics by which animals balance multiple important, widespread traits (reproduction, locomotion, and self-maintenance) in variable environments.
