A trade-off between growth and starvation endurance in a pit-building antlion

Abstract

Trade-offs have a central role in evolutionary ecology and life-history theory. Here, we present evidence for the existence of a rarely studied trade-off between growth rate and starvation endurance in larvae of a pit-building antlion. We first manipulated antlions' feeding regime and obtained a spectrum of growth rates. Next, we starved the antlions and documented their rate of mass loss. Antlions growing faster during the feeding phase also lost mass faster during the successive starvation period, implying the existence of an induced trade-off between fast growth and starvation endurance. Finally, we fed all antlions with prey items of similar mass and measured both the giving-up prey mass (i.e. the remaining body mass of the prey that was not converted into predator body mass), and growth efficiency of antlions (i.e. proportion of prey consumed, negatively correlated with giving-up prey mass). The giving-up mass was negatively correlated with the growth rate of the antlions during the feeding phase, and positively correlated with their growth rate during the starvation phase (the opposite pattern was evident when examining growth efficiency), incongruently with the common phenomenon of growth compensation (i.e. extracting more of the prey after a starvation period). We suggest that antlion larvae can adopt a physiological mode bounded by two extremes: one extreme is adapted to starvation, involving reduced metabolic rates but also reduced capability to exploit prey, while the other is adapted to fast growth, allowing an efficient exploitation of prey, but at the expense of lowered starvation endurance.