Effect of agricultural land-use change on ant dominance hierarchy and food preferences in a temperate oak forest

Abstract

BackgroundThe discovery-dominance trade-off is the inverse relationship between the ability of a species to discover resources and the species’ dominance of those resources; a paradigm used to explain species coexistence in ant communities dependent on similar resources. However, factors such as stress (e.g., temperature) or disturbance (e.g., removal of biomass) associated with the change in land use, can modify this trade-off. Here, we aimed to determine the potential effects of land use change on dominance hierarchy, food preferences and on the discovery-dominance trade-off.MethodsAn experiment with baits was used to investigate the dominance hierarchies of ant communities in a temperate mountain habitat in central Mexico. We evaluated the dominance index (DI), food preferences and discovery-dominance trade-offs of ants inhabiting two types of vegetation: a native oak forest and agricultural land resulting from agricultural land use and grazing.ResultsThe ant communities in both environments were comprised of three species of ants (Monomorium minimum, Myrmica mexicana, and Camponotus picipes pilosulus), four morphospecies (Pheidole sp.1 and Pheidole sp.2, Temnothorax sp. and Lasius sp.) and one genus (Formica spp.). All Formicidae showed values of intermediate to low DI, and this factor did not seem to be influenced by the change in land use. Ants in the modified vegetation (i.e., agricultural land) were found to be numerically greater. Overall, a higher number of visits were registered to the tuna bait, although the duration of foraging events to the honey baits was longer. However, foraging times were dependent on the species considered: the generalized Myrmicinae, M. minimum, the ant species with highest DI, foraged for longer periods of time in the agricultural land and on the tuna bait. Meanwhile, the cold-climate specialist Formica spp., with a lower DI, foraged for longer periods of time in the oak (although not significant) and on the honey bait. We found little evidence of the discovery-dominance trade-off; instead, we found considerable diversity in the strategies used by the different species to access resources. This range of strategies is well represented by the generalized Myrmicinae M. minimum, the cold-climate specialists Formica spp. and Temnothorax sp., and the rare species, as the cold climate specialist Lasius sp. (insinuators).ConclusionsOur evaluation shows that transformation of the original habitat does not appear to affect the hierarchical dominance of the ant communities, but it does affect their food preferences. Species with higher DI values such as the generalized Myrmicinae are more skilled at resource acquisition in modified habitats. Our results suggest that change in land use promotes an increase in the diversity of foraging strategies used by different ant species. This diversity may contribute to resource partitioning which favors coexistence.

Ants (Hymenoptera: Formicidae) in a Temperate Ecosystem from La Malinche National Park, Mexico

“…This is interesting given that this functional group is associated with sites with high levels of disturbance and stress; although some of these species are found only on agricultural land (D. insanus and F. densiventris), the majority were found in both vegetation types. The generalized Myrmicinae, which are associated with warm, open environments, were found in both vegetation types, although numerically they were better represented in agriculture land (Castillo-Guevara et al 2019). Of the 23 species of ants recorded in our study, 2 cold-climate specialist species were exclusively present in the oak forest, whereas 4 species that were opportunists, cold-climate specialists, and tropical climate specialists were collected exclusively from agricultural land (Table 1).…”

Arboreal twig-nesting ants form dominance hierarchies over nesting resources

“…Microclimatic factors also disrupt dominance hierarchies. For instance, environmental variation in coffee systems is likely to influence dominance hierarchies (Philpott & Foster, 2005; Perfecto & Vandermeer, 2011; Castillo-Guevara et al, 2019). Occurrence of fire can disrupt dominance hierarchies in specialist ants in Acacia trees resulting in increased abundance of subordinate ants (Sensenig et al, 2017).…”

“…For example, Formica species dominating a boreal ecosystem divert resources away from subdominant competitors (Savolainen & Vepsäläinen, 1988). In Mediterranean ecosystems, subdominant species forage at nearly lethal environmental conditions while dominant species reduce their own mortality risk by foraging at more favorable temperatures (Cerdá, Retana & Manzaneda, 1998; Castillo-Guevara et al, 2019). In tropical ecosystems, competing arboreal ants can be structured into a dominance hierarchy with higher ranked ant species having greater access to nesting sites and extrafloral nectaries (Blüthgen, Stork & Fiedler, 2004; Díaz-Castelazo et al, 2004).…”

Neither ant dominance nor abundance explain ant-plant network structure in Mexican temperate forests

“…To evaluate the dominance hierarchy of MNP’s ants, we used the Dominance Index (DI) data that were calculated in a previous study at the same site from April to September of 2015 ( Castillo-Guevara et al, 2019 ). In this study, nine sampling points separated by 10 m were established in each transect.…”

“…Ant abundance was quantified using the frequency the species was reported in the pitfall traps to avoid overestimating the species that have more efficient recruitment systems (Gotelli et al, 2011). The average numerical DI was calculated for each ant species recorded in the previous study at MNP (Castillo-Guevara et al, 2019), and analyzed de novo in FBSP. The formula used was:…”