Competition trade‐offs in the organisation of a Mediterranean ant assemblage

Abstract

1. The organisation of an ant assemblage inhabiting an olive orchard in central Italy was analysed and patterns of dominance among ant species were described in order to assess (i) the relationship between thermal dependency and degree of behavioural dominance, and (ii) the relationship between dominance and discovery ability. 2. Activity patterns of the most abundant species on trees were examined in a sample of 120 trees during spring and summer. The degree of behavioural dominance and the ability of different species to discover new food sources were assessed using tuna baiting on a subset of 80 trees. 3. Different ant species showed contrasting patterns of activity. Some species (such as Lasius lasioides, Camponotus lateralis, and Camponotus piceus) were most active during the warmer part of the day, while others restricted their activity to the cooler hours (Camponotus aethiops and Plagiolepis pygmaea). Some species (such as Crematogaster scutellaris) were active irrespective of the time of day. 4. No clear relationship was observed between temperature of maximal activity and degree of behavioural dominance. There was, however, a positive relationship between behavioural dominance and thermal range of activity. A positive relationship between dominance and ability to find resources, with the most behaviourally dominant and aggressive species being most efficient in finding food items, was also observed. 5. The results support the idea that the temperature–dominance relationship is much more complex in Mediterranean‐type habitats than in other ecosystems. Of particular interest is the positive dominance–discovery relationship. This finding contrasts with previous investigations, which reported a negative relationship between dominance and discovery ability and suggested that this pattern plays a role in promoting the coexistence of species in ant communities.

Temperature-mediated coexistence in temperate forest ant communities

“…In addition, species that were subordinate did not discover baits faster than did dominant species. Similarly, Santini et al (2007) found no evidence for the discovery-dominance or the dominance-thermal tolerance tradeoff in a Mediterranean ant assemblage, though such tradeoffs likely promote coexistence in other Mediterranean ant assemblages 1998a). Fellers (1987) found evidence of the discovery-dominance tradeoff in other temperate forest ant communities.…”

Experimental evidence for mediation of competition by habitat succession

“…Physical attributes of these stands may differ enough from older forests to reverse the effects of interactions. For example, temperature, which depends on successional stage, may regulate competitive interactions (Cerda´et al 1988, 1997, Santini et al 2007. Habitat complexity may also reduce competitive interactions (Petren and Case 1998, Gray et al 2000, so the greater cover of dead wood in 0-4-year-old stands may limit competitive interactions with F. aquilonia.…”

Competition hierarchy and plant defense in a guild of ants on tropical Passiflora

“…Ant aggressiveness was assessed by calculating a BDI based on Santini et al (2007). The number of times individual ants were dominant or subordinate was recorded for each pair of ant species that encountered each other.…”