The structure of mutualistic networks provides clues to processes shaping biodiversity [1-10]. Among them, interaction intimacy, the degree of biological association between partners, leads to differences in specialization patterns [4, 11] and might affect network organization [12]. Here, we investigated potential consequences of interaction intimacy for the structure and coevolution of mutualistic networks. From observed processes of selection on mutualistic interactions, it is expected that symbiotic interactions (high-interaction intimacy) will form species-poor networks characterized by compartmentalization [12, 13], whereas nonsymbiotic interactions (low intimacy) will lead to species-rich, nested networks in which there is a core of generalists and specialists often interact with generalists [3, 5, 7, 12, 14]. We demonstrated an association between interaction intimacy and structure in 19 ant-plant mutualistic networks. Through numerical simulations, we found that network structure of different forms of mutualism affects evolutionary change in distinct ways. Change in one species affects primarily one mutualistic partner in symbiotic interactions but might affect multiple partners in nonsymbiotic interactions. We hypothesize that coevolution in symbiotic interactions is characterized by frequent reciprocal changes between few partners, but coevolution in nonsymbiotic networks might show rare bursts of changes in which many species respond to evolutionary changes in a single species.

The structure of mutualistic networks provides insights into ecological and coevolutionary dynamics of interacting species. However, the spatial effect has only recently been incorporated as a factor structuring mutualistic networks. In this study, we evaluated how the topological structure and species turnover of ant–plant mutualistic networks vary over a spatial gradient. We showed that although the ant and plant composition of networks changed over space, the central core of generalist species and the structure of networks remained unaltered on a geographic distance of up to 5099 m in the southern Brazilian Amazon. This finding indicates that independently of variation in local and landscape environmental factors, the nonrandom pattern organization of these interacting assemblages do not change. Finally, we suggest that a stable core can increase the potential for coevolutionary convergence of traits among species from both sides of the interaction within the community. These findings contribute to our understanding of the maintenance of biodiversity and coevolutionary processes.

We studied the relationship between Hirtella myrmecophila (Chrysobalanaceae), a common but littlestudied Amazonian ant-plant that produces leaf-pouches as domatia, and its obligate ant partner, Allomerus octoarticulatus. Field observations revealed that H. myrmecophila drops domatia from older leaves, a characteristic that is unique among myrmecophytes. The physiological mechanism for abortion of domatia is currently unknown, but this characteristic allows for the existence, within the same plant, of branches with and without ants. Older branches generally bear only old leaves with no domatia and therefore have no ants, whereas younger branches have leaves of various ages. Ants forage mainly on new leaves, and experimental removal of ants showed that A. octoarticulatus is crucial for defense of these leaves against insect herbivores. However, A. octoarticulatus also acts as a castration parasite, severing the plant's inflorescences. Mature flowers and fruits were only found on older branches with no ants, and flower production was 8 times greater on plants whose ants were experimentally removed than on control plants. Given the reproductive costs inflicted by its mutualistic partner, we suggest that abortion of domatia is a strategy developed by H. myrmecophila to minimize the effects of cheating by A. octoarticulatus. These results support the view that evolutionary conflicts of interest between mutualistic species often impose selection for cheating on the partner, as well as for mechanisms to retaliate or to prevent super-exploitation. Opposing selection pressures, operating independently on the two partners, probably help to maintain the evolutionary stability of this mutualistic relationship.

Building bridges between environmental and political agendas is essential nowadays in face of the increasing human pressure on natural environments, including wetlands. Wetlands provide critical ecosystem services for humanity and can generate a considerable direct or indirect income to the local communities. To meet many of the sustainable development goals, we need to move our trajectory from the current environmental destructive development to a wiser wetland use. The current article contain a proposed agenda for the Pantanal aiming the improvement of public policy for conservation in the Pantanal, one of the largest, most diverse, and continuous inland wetland in the world. We suggest and discuss a list of 11 essential interfaces between science, policy, and development in region linked to the proposed agenda. We believe that a functional science network can booster the collaborative capability to generate creative ideas and solutions to address the big challenges faced by the Pantanal wetland.

Despite the importance and increasing knowledge of ecological networks, sampling effort and intrapopulation variation has been widely overlooked. Using continuous daily sampling of ants visiting three plant species in the Brazilian Neotropical savanna, we evaluated for the first time the topological structure over 24 h and species-area relationships (based on the number of extrafloral nectaries available) in individual-based ant-plant networks. We observed that diurnal and nocturnal ant-plant networks exhibited the same pattern of interactions: a nested and non-modular pattern and an average level of network specialization. Despite the high similarity in the ants’ composition between the two collection periods, ant species found in the central core of highly interacting species totally changed between diurnal and nocturnal sampling for all plant species. In other words, this “night-turnover” suggests that the ecological dynamics of these ant-plant interactions can be temporally partitioned (day and night) at a small spatial scale. Thus, it is possible that in some cases processes shaping mutualistic networks formed by protective ants and plants may be underestimated by diurnal sampling alone. Moreover, we did not observe any effect of the number of extrafloral nectaries on ant richness and their foraging on such plants in any of the studied ant-plant networks. We hypothesize that competitively superior ants could monopolize individual plants and allow the coexistence of only a few other ant species, however, other alternative hypotheses are also discussed. Thus, sampling period and species-area relationship produces basic information that increases our confidence in how individual-based ant-plant networks are structured, and the need to consider nocturnal records in ant-plant network sampling design so as to decrease inappropriate inferences.