Who is the top dog in ant communities? Resources, parasitoids, and multiple competitive hierarchies

Abstract

A wide variety of animal communities are organized into interspecific dominance hierarchies associated with the control and harvest of food resources. Interspecific dominance relationships are commonly found to be linear. However, dominance relations within communities can form a continuum ranging from intransitive networks to transitive, linear dominance hierarchies. How interference competition affects community structure depends on the configuration of the dominance interactions among the species. This study explores how resource size and the trait-mediated indirect effect (TMIE) specialist phorid fly parasitoids exert on interference competition, affect the transitive nature of competitive interactions in an assemblage of woodland ants. I quantify the linearity of networks of interactions associated with large and small food resources in the presence and absence of phorid parasitoids. Two distinct, significantly linear dominance hierarchies exist within the ant assemblage depending on the size of the disputed resource. However, the presence of phorid fly parasitoids eliminates the linearity of both dominance hierarchies. The host's phorid defense behaviors reduce the competitive asymmetries between the host and its subdominant competitors, increasing the indeterminacy in the outcome of competitive interactions. Thus, both resource size variation and phorid-induced TMIEs appear to facilitate coexistence in assemblages of scavenging ants.

Resource discovery in ant communities: do food type and quantity matter?

“…In the traditional interpretation of the trade-off, good discoverers are subordinate species that maximised their resource encounter rates so as to access resources before being displaced from them by behavioural dominants during harvest (Vepsäläinen & Pisarski, 1982;Fellers, 1987;Morrison, 1996). Individual foragers of subordinate species may pre-empt competitive interference at resources by arriving first at small resources that they can quickly exhaust or carry away (LeBrun, 2005;Adler et al, 2007). Being a good discoverer may also be a means by which subordinates access preferred resources.…”

RETRACTED ARTICLE: Interspecific competition among ants in the boreal forest: Testing predictions from a linear hierarchical competition model

“…Cerdµ et al, 1997), resource size (e.g. LeBrun, 2005), resource type (e.g. Sanders and Gordon, 2003) and parasitoids (e.g.…”

Exploitative Competition and Risk of Parasitism in Two Host Ant Species: The Roles of Habitat Complexity, Body Size, and Behavioral Dominance

“…Psyche Ant communities are not traditionally considered to be structured by top-down forces from predators. However, community composition can be influenced by specialist Dipteran parasitoids (Apocephalus: Phoridae) that attack host ant species, induce behavioral responses in their hosts, and alter the outcome of interspecific competition in the community [26][27][28][29][30][31][32]. Habitat complexity has been shown to benefit the host ant species Pheidole diversipilosa and P. bicarinata during interference competition with nonhost ant species by providing refuge from parasitoids.…”

“…Refuge allows hosts to maintain similar numbers of soldiers during head-to-head competition as in competitive bouts without parasitoids [13]. These two host ants cooccur in the same habitat and are dominant to most other ants in the community, but P. bicarinata is behaviorally subordinate to P. diversipilosa [30]. This difference in dominance has the potential to impact benefits derived from habitat complexity during exploitative competition.…”

“…; soldiers: 0.44 versus 0.26 mg, resp. ), and wins 15% more of its interactions with all other species in the local assemblage [30]. First, we determine whether habitat complexity influences the time it takes each host species to find resources (the "discovery" component of exploitative competition, [38]).…”