The effect of resource availability on interspecific competition between a native and an invasive ant

Abstract

Interspecific competition influences the composition of ecological communities. Species may differ in their needs for different resources, therefore resource availability may determine the outcome of interspecific interactions. Species often compete over food, shelter or both. When more than one resource is limited, different species may prioritize different resources. To determine the impact of resource availability on the competitive relationship between an invasive and a native species, we examined interactions between groups of the invasive Argentine ant ( Linepithema humile ) and the native odorous ant ( Tapinoma sessile ) over (1) food, (2) shelter or (3) both simultaneously. We further examined the mechanisms underlying the competitive relationship, asking whether aggressive interactions, exploratory behaviour or the order of arrival at a resource explained resource use. Shelter was preferred by both species when no competitors were present. In a competitive setting, L. humile groups controlled shelter through aggressive displacement but lost control over food due to investment of workers in the control of shelter. Thus, there are tradeoffs when competing over multiple resources and aggressive interactions allow invasive species to displace native species from a preferred resource. This article is part of the theme issue ‘Intergroup conflict across taxa’.

Intergroup conflict: origins, dynamics and consequences across taxa

“…One such factor may be changes in the groups' ecology, as suggested by various contributions to the current theme. For instance, Neumann & Pinter-Wolman [ 32 ] highlight that groups may need to trade off which resources to compete for under restricted environments with limited resources. In an experimental set-up, both the invasive Argentine ant ( Linepithema humile ) and the native odorous ant ( Tapinoma sessile ) prefer to occupy shelter and food locations.…”

“…Intergroup conflict has also been observed in spider monkeys (Ateles paniscus) [19], hyaenas (Crocuta crocuta) [20], wolves (Canis lupus) [21], meerkats (Suricata suricatta) [22], banded mongooses (Mungos mungo) [23,24], in various group-living birds [25][26][27] and social fishes [28]. Social insects raid neighbouring colonies and kill enemy conspecifics [29][30][31][32][33].…”

“…It provides, for the first time, to our knowledge, a side-by-side treatment of intergroup conflict across taxa, detailing the origins and consequences of intergroup conflict. Each in their own way, the contributions provide insight on intergroup conflict for social insects [32,33], social fishes [40], group-living birds [26,27], non-primate mammals such as banded mongoose [24], lions and wolves [17], several monkey species [41][42][43], chimpanzees [18,44] and humans [45][46][47].…”

Intraspecific competition for a nest and its implication for the fitness of relocating ant colonies

“…In the case of woodland ants like Camponatus ferrugineus, Lasius alienus, Formica subsericea and Prenolepis imparis studies demonstrate a trade-off between resource discovery and behavioral dominance of resources (12, 51). If the group size is not similar and they compete for the same resource, then the smaller colony was at a disadvantage as members engaged in interactions with the competitors could not simultaneously undertake the assigned tasks (59). In the current study, we hypothesize that smaller colonies were not able to compete for the resource because their workforce was mostly occupied with interactions with larger colonies and could not allocate members for exploration leading to delayed discovery, higher latency to initiate tandem run.…”

From inter-group conflict to inter-group cooperation: insights from social insects

“…Indeed, the above examples notwithstanding, group-level combat among conspecifics is relatively rare in the social insects. The weaponry borne by social insect workers is primarily used to defend their resources (stored food and vulnerable proteinrich brood) from heterospecific predators and kleptoparasites, rather than from conspecifics [22,25,26]. Many conspicuous colony-level conflicts are in fact attempts to withstand heterospecific robbing [22,27,28].…”