Structural changes over time in individual‐based networks involving a harvester ant, seeds, and invertebrates

Abstract

1. Harvester ants perform important ecological functions, such as seed predation and redistribution of nutrients in the soil, through a complex of ecological interactions. Most studies are static descriptions of network structure, while their temporal organisations and the factors that modulate it have been neglected. 2. This study describes the temporal organisation and the influence of climatic variables (e.g. temperature and rainfall) on network structure between a harvester ant species and its food resources (seeds and invertebrates) in the Brazilian savanna over a 1‐year period. In addition, considering the ant–seed networks, the relationship between the size of seeds collected by ants and the distance travelled was examined, as well as how this relationship behaves over time. 3. For all network types (ant–seed, ant–invertebrate, and combined) there was great structural variation throughout the year. Among climatic variables, only rainfall influenced the properties of ant–invertebrate networks, presenting a positive influence on diversity of interactions and a negative influence on network specialisation. Finally, this study shows that harvester ants tend to collect larger seeds in the vicinity of the nest (< 5 m) and smaller seeds at greater distances, and this relationship appears to be constant over time. 4. This study highlights that ecological networks are useful tools with which to understand the temporal organisation of ecological functions. In addition, climatic changes, mainly in the rainfall regime, may interfere directly in the availability of resources and ultimately in the interactions between harvester ants and their food resources.

Climate seasonality drives ant–plant–herbivore interactions via plant phenology in an extrafloral nectary‐bearing plant community

“…Thus, some ants can change their foraging patterns according to the availability of resources in the environment (Belchior, Del‐Claro, & Oliveira, 2012; Whitford & Jackson, 2007). For instance, Anjos, Luna, Borges, Dáttilo, and Del‐Claro (2019) showed that granivorous ants can change their foraging behaviour due to the seasonality of the environment, which results in changes in resource availability (also see Donoso, Johnston, & Kaspari, 2010). Therefore, in our region we observe that biotic and abiotic factors lead to the simultaneous occurrence of EFNs, ants and herbivores, and the production of new leaves.…”

Harvester ant seed removal in an invaded sagebrush ecosystem: Implications for restoration

“…For example, temperatures alter daily foraging activity which can be geographically dependent (Stuble et al, 2013(Stuble et al, , 2014; however, harvester ants generally display unimodal activity in cooler months and bimodal patterns in warmer months (Crist & MacMahon, 1992;Stuble et al, 2013Stuble et al, , 2014. Vegetation structure, resource distance, and biotic factors, such as larger colonies and neighboring nests, are additional factors that can influence harvester ant foraging (Anjos et al, 2019;Gordon & Kulig, 1996;MacMahon et al, 2000). Our final objective was to evaluate the relative effects these factors had on seed removal by harvester ants.…”

Local and Temporal Effects on Ant Richness, Recruitment and Resource Dominance in Two Cerrado Areas

“…Species are delimited by a heterogeneous distribution of resources and environmental conditions (Wang et al, 2001), which determine potential local interactions (Perfecto & Vandermeer, 1996;Camarota et al, 2016;Queiroga & Moura, 2017). For instance, some authors discuss how annual temperature and rainfall affect ants' survival and how warmer and wetter conditions can increase the diversity and frequency of ant-plant interactions (Costa et al, 2018;Anjos et al, 2019;Bujan et al, 2020).…”