The network structure of myrmecophilic interactions

Abstract

1. Ants establish mutualistic interactions involving a wide range of protective relationships (myrmecophily), in which they provide defence against enemies and partners provide food rewards and/or refuge. Although similar in the general outcome, myrmecophilic interactions differ in some characteristics such as quantity and quality of rewards offered by partners which may lead to different specialisation levels and, consequently, to different network properties.2. The aim of this study was to identify structural patterns in myrmecophilic interaction networks, focusing on aspects related to specialisation: network modularity, nestedness and taxonomic relatedness of interaction ranges. To achieve this, a database of networks was compiled, including the following interactions: ants and domatia-bearing plants (myrmecophytes); ants and extrafloral nectary-bearing plants (EFNs); ants and floral nectary-bearing plants (FNs); ants and Lepidoptera caterpillars; and ants and Hemiptera.3. Myrmecophilic networks differed in their topology, with ant-myrmecophyte and ant-Lepidoptera networks being similar in their structural properties. A continuum was found, ranging from highly modular networks and phylogenetically structured interaction ranges in ant-myrmecophyte followed by ant-Lepidoptera networks to low modularity and taxonomically unrelated interaction ranges in ant-Hemiptera, EFN and FN networks.4. These results suggest that different network topologies may be found across communities of species with similar interaction types, but also, that similar network topologies can be achieved through different mechanisms such as those between ants and myrmecophytes or Lepidoptera larvae. This study contributes to a generalisation of myrmecophilic network patterns and a better understanding of the relationship between specialisation and network topology.

Does biological intimacy shape ecological network structure? A test using a brood pollination mutualism on continental and oceanic islands

“…Finally, the Ryukyu networks (which we compiled from a phylogenetic study not explicitly examining network architecture) were not as intensively sampled as our Polynesian networks, so it is possible that further sampling there may uncover additional moth species or links. We also note that although a number of studies have examined attributes of network structure in other intimate mutualisms (Cagnolo & Tavella, ; Ollerton et al., ; Ricciardi et al., ), they have not explicitly tested both reciprocal specialization and modularity in the same assemblages. Additional studies testing the biological intimacy hypothesis in these and other intimate mutualisms (such as other ant‐myrmecophile and brood pollination assemblages) would be extremely valuable.…”

“…Modularity varies across Glochidion – Epicephala networks as is the case in both intimate and nonintimate mutualisms (Olesen et al., ), although all continental and one oceanic (Moorea) island networks show significant modularity. In the combination of these two structural properties, leafflower‐moth networks are thus structurally similar to ant‐myrmecophyte networks (Blüthgen et al., ; Cagnolo & Tavella, ; Dáttilo et al., ; Guimarães et al., ); with regard to their high reciprocal specialization, they are similar also to the intimate mutualism between Alpheus shrimps and gobies (Thompson et al., ). These findings thus constitute an important independent test of the biological intimacy hypothesis.…”

Merging evolutionary history into species interaction networks

“…Asymmetry in interaction conservatism among interacting groups has also been observed in mutualistic networks , although less pronounced (Fontaine & Th ebault 2015). For instance, in plant-pollinator and seed dispersal networks, animals tend to have higher conservatism in their interactions than plants ( constraints in partner use appear for shrimps (Thompson et al 2013), and myrmecophilic networks, where ants interact with phylogenetically related plant species (Cagnolo & Tavella 2015). Differences in the conservatism of interactions between interacting groups could also greatly influence the evolution of the network, with the higher conservatism group potentially driving the evolution of the system (Jordano 2010).…”

“…Other examples of phylogenetic asymmetry include marine goby–shrimp mutualistic networks, where the evolutionary constraints in partner use appear for shrimps (Thompson et al . ), and myrmecophilic networks, where ants interact with phylogenetically related plant species (Cagnolo & Tavella ).…”

Few Ant Species Play a Central Role Linking Different Plant Resources in a Network in Rupestrian Grasslands

“…In fact, recent findings have shown that ant dominance over resource usage is the main mechanism responsible for differences in specialization of networks formed by interactions between ants and extrafloral nectary (EFN)-bearing plants, and between ants and honeydew-producing hemipterans [25]. Likewise, results from compiled datasets suggest that ant-flower networks are more specialized (i.e., more modular) than ant–Hemiptera and ant-EFN networks [26]. …”