Behavioural mediators of genetic life-history trade-offs: a test of the pace-of-life syndrome hypothesis in field crickets

The pace-of-life syndrome (POLS) hypothesis predicts associations between life-history and ‘risky’ behaviours. Individuals with ‘fast’ lifestyles should develop faster, reproduce earlier, exhibit more risk-prone behaviour, and die sooner than those with ‘slow’ lifestyles. While support for POLS has been equivocal to date, studies have relied on individual-level (phenotypic) patterns in which genetic trade-offs may be masked by environmental effects on phenotypes. We estimated genetic correlations between life-history (development, lifespan, size) and risky behaviours (exploration, aggression) in a pedigreed population of Mediterranean field crickets (Gryllus bimaculatus). Path analyses showed that behaviours mediated some genetic relationships between life-history traits, though not those involved in trade-offs. Thus, while specific predictions of POLS-theory were not supported, genetic integration of behaviour and life-history was present. This implies a major role for risky behaviours in life-history evolution.