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Keywords:

  • Ants (Formicidae);
  • behavioural dominance;
  • spatial heterogeneity;
  • species coexistence;
  • thermal tolerance

1. Ecological trade-offs in ant (Hymenoptera: Formicidae) assemblages and their implications for coexistence boast a rich history in entomology. Yet investigations of trade-offs have largely been limited to homogeneous environments. We examined how environmental context modifies trade-off expression in an ant assemblage spanning a heterogeneous region in central Florida, U.S.A.

2. We examined how trade-off expression is altered among two contrasting habitat types: open shrub and forest. We tested for the presence of the dominance-discovery trade-off and two dominance-thermal tolerance trade-offs by estimating behavioral dominance, discovery ability, and thermal tolerance (foraging thermal limit, lethal temperature, and maximal abundance temperature) for a wide range of interacting ant species.

3. We found significantly linear dominance hierarchies in both shrub and forest habitats, showing dominant species out-compete subordinates for food resources. In thermally stressful shrub habitats, subordinates exhibit higher thermal tolerances, take greater thermal risks, and reach maximum forager abundances at higher temperatures than do dominant species. This suggests temperature mediated trade-offs control coexistence in shrub habitat. In thermally moderate forest habitat, we found limited evidence for trade-offs between competitive dominance and resource discovery or between dominance and thermal traits, implying other processes control coexistence. These results demonstrate that trade-offs controlling ant coexistence may be contingent on environmental context.