Mechanisms facilitating ant species coexistence in the burnt and unburnt grassland

Abstract

Many ant species can coexist in a small space, which is surprising because ants are competitive. Trade-offs have been proposed as mechanisms that facilitate such coexistence. Therefore, the current study assessed the temperature-dominance trade-off and the bait discovery-dominance trade-off to determine if any of these facilitate coexistence in the burnt and unburnt grassland habitat in KwaZulu-Natal Province, South Africa. We used cat food as bait in two grassland plots replicated five times to observe ant activities every 15 min for 3 h, recorded ant interactions and foraging surface temperature. We observed a negative relationship between minimum temperature and dominance. This suggests that dominant ants may tolerate even lower temperatures, meaning they have a broader range of foraging temperatures. There was a significant relationship between the percentage number of baits discovered and dominance in the burnt plot. Dominant ants located most baits in both plots. Also, they could discover baits much faster in the unburnt plot. Both burnt and unburnt plots showed no significant relationship between time to discover baits and dominance. This study also revealed that burning influenced competitive interactions and not trade-offs. However, burning may not explain the increase/decrease of competitive interaction, as this can be explained by temperature, since the study showed that temperature varied considerably between the burnt and unburnt plots. There is a need to examine other possible mechanisms that may facilitate coexistence in this grassland system.