In order to understand the dynamics of co-evolution it is important to consider spatial variation in interaction dynamics. We examined the relative importance of ant activity, diversity and species ...identity in an ant seed dispersal mutualism at local, regional and continental scales. We also studied the determinants of seed dispersal rates and dispersal distances at eight sites in the Eneabba sandplain (29.63 S, 115.22 E), western Australia to understand local variation in seed dispersal rate and distance. To test the generality of the conclusions derived from the eight local sites, we established 16 sites along a 1650-km transect in western Australia, covering 11° of latitude and a six-fold increase in rainfall, at which we sampled the ant assemblage, estimated ant species richness and ant activity and observed the removal rate of myrmecochorous seeds. We also assessed the importance of ant species identity at a continental scale via a review of studies carried out throughout Australia which examined ant seed dispersal. Among the eight sandplain shrubland sites, ant species identity, in particular the presence of one genus, Rhytidoponera, was associated with the most dispersal and above average dispersal distances. At the landscape scale, Rhytidoponera presence was the most important determinant of seed removal rate, while seed removal rate was negatively correlated with ant species richness and latitude. Most ant seed removal studies carried out throughout Australia reinforce our observations that Rhytidoponera species were particularly important seed dispersers. It is suggested that superficially diffuse mutualisms may depend greatly on the identity of particular partners. Even at large biogeographic scales, temporal and spatial variation in what are considered to be diffuse mutualisms may often be linked to variation in the abundance of particular partners, and be only weakly - or negatively - associated with the diversity of partners.
Taxonomic stability is essential if the requirements of a host of stakeholders - health professionals, farmers, environmental consultants and public servants, to name just a few occupations - who ...need advice on particular organisms are to be satisfied. In many cases this involves the production of species lists. Reliably identified lists of species of one or more groups of taxa are desirable if not mandatory for decision making by stakeholders in environmentally-based long-term research. Both straightforward factors (i.e., quality of the taxonomy that is associated with the species list) and more complex factors behind the compilation (the philosophical undergirding that determines how the species are differentiated in the first place) can often make its interpretation a problematic undertaking, particularly when taxonomic changes occur during the course of long-term studies. Concepts behind the naming of species can deal with patterns or with underlying processes. Whichever way it is undertaken, traditional taxonomy is often slow. This paper evaluates recent attempts to devise cheap, cost effective methods (i.e., barcoding, metagenomics) that will make the taxonomic process more uniform, less labor intensive and hopefully more stable over time.
The sight of land managers poring over ant checklists is a regular occurrence in Australia, where ant monitoring has been successfully applied to a wide range of land-use situations. The robustnes of ...ants as ecological indicators has been consistently demonstrated, and is supported by an extensive understanding of their community dynamics in relation to disturbance. Despite the widespread recognition of the value of terrestrial invertebrates as bioindicators, the use of ants represents one of the few examples where invertebrates are widely adopted in land management as indicator organisms, as opposed to being consigned to the "too hard" basket. The use of invertebrates as bioindicators in land management will always require specialist expertise and a substantial investment in resources. However, research in Australia shows that invertebrate monitoring does not require comprehensive surveys, and that it is possible to simplify sampling and processing without compromising indicator performance. This should help take invertebrates out of the "too hard" basket and provide land managers with a powerful tool for environmental monitoring.
The dramatic increased rates of uncontrolled urbanisation in various parts of the World have resulted in loss of native species and overall threats to biodiversity. Over the last few decades Saudi ...Arabia has witnessed a remarkably rapid population growth and unparalleled levels of urbanisation, leading to threats to biodiversity. In this study we focused on arid city (Riyadh, Saudi Arabia) where ant assemblages cross an urban-rural gradient. Ants were collected by pitfall traps from 15 sites along three different urbanisation gradients at 3-monthly intervals throughout 1 year. Ant abundance, species richness, evenness, and α diversity were consistent across the urbanisation gradient. However, significant differences were observed in ant β diversity and assemblage composition between rural and urban, suburban and urban, but not between rural and suburban sites. Eleven ant species were identified as indicator species (IV values between 50.7% and 80.7%). These ant assemblages were influenced by flora, ground cover, soil variables, and urbanisation characteristics. To conclude, we found a significant effect of urbanisation on the β diversity and composition of ant assemblages.
•Globally, our knowledge is focused on a limited set of taxonomic groups.•We know more about small and young areas, degraded by mining or agriculture.•Planted or seeded areas monitored by diversity ...or richness indexes are the most common investigations.•Groups evaluated and functional group approaches have been increasing in recent years.•Incomplete-Puzzle hypothesis can be a more realistic approach in restoration scenarios.
Biodiversity promotion activities, such as ecological restoration, are recognized as instruments to arrest and mitigate the diminishing health of ecosystems. The restoration of fauna is a fundamental component of this process but, despite this, there are few studies that compile and discuss the knowledge produced on this topic. Hence, by seeking a general understanding of what we currently know about terrestrial invertebrates as bioindicators in restored ecosystems, the present work sought to organize knowledge in such a way as to indicate gaps and opportunities for both researchers and restorers. To this end, we searched for topics associated with restoration ecology in the Web of Science database, identifying which invertebrate groups have been studied in relation to intrinsic characteristics of ecological intervention, including type of biome, type of disturbance, restoration technique, age, project size, and indices used. We found 154 studies published between 1995 and 2018: 93.5% of which were from 2002 onwards. We detected a growing number of studies and a tendency to evaluate functional groups. Moreover, there was a high concentration of studies within a few taxonomic groups, notably Hymenoptera (Formicidae), Coleoptera, and Lepidoptera. Many of the restoration scenarios are poorly studied, for example, in temperate coniferous forests or taiga biomes, previous disturbances caused by pollution or urbanization, under certain restoration techniques such as brushwood transposition, and investigations in large or old areas. There was also a paucity of information concerning community or population-level measures of restoration success, such as the structure of communities, biomass, and dominance. We discuss some consequences of these knowledge gaps. Finally, we indicate which taxonomic groups have been evaluated in relation to each restoration characteristic considered, resulting in guidance for those wishing to engage in research and monitoring of such organisms during the restoration process.
•Biodiversity surrogates provide meaningful information at a lower cost and effort.•Ants are often used in such environmental assessments.•We seek a useable substitute surrogate for taxonomic and ...functional ant diversity.•For this, we tested four potential ant surrogates at 65 Atlantic rainforest sites.•Of the species and functional group surrogates, mixed-level was the best.
Comprehensive biodiversity inventories are expensive and time-consuming to achieve, especially for groups of megadiverse organisms. One approach to resolve such situations is to utilize biological substitutes, referred to as surrogates. A surrogate should provide meaningful information at a lower cost and/or effort than the original level of resolution. Studies have shown that species richness is often not the best or most appropriate component or predictor of biodiversity. Functional diversity can be used as a measurement of the ecological differentiation between habitats or between biological functions. We evaluated the use of several taxonomic metrics as potential surrogates for leaf-litter ant assemblages distributed in 65 Atlantic rainforest sites. Our goal was to find reliable and economic substitutes for both taxonomic and functional leaf-litter ant diversity and composition. We tested four potential surrogate approaches for taxonomic metrics and three for functional group metrics. Additionally, we also evaluated the time and costs involved. We used a large leaf-litter ant database that comprises 364 ant species, respectively classified into 13 or 26 ant functional groups based on either a general and specific resolution. Subfamily was found to be an unacceptable surrogate for both taxonomic and functional group metrics. Mixed-level and indicator taxa metrics were rated as ‘excellent’ taxonomic surrogates. Mixed-level and genus metrics were rated as ‘excellent’ or ‘acceptable’ functional group surrogates when considering the most general functional resolution, while mixed-level and genus were considered as ‘excellent’ surrogates when considering the more specific resolution. The monetary and time costs to identify ants to genus level were lower than those using indicator taxa and mixed-level metrics. The use of a certain higher taxon functional and taxonomic surrogates allows a reduction of survey and analysis costs while still enabling the analysis of biological diversity from the taxonomic and functional point of view.
Ascertaining the costs and benefits of mutualistic interactions is important for predicting their stability and effect on community dynamics. Despite widespread designation of the interaction between ...ants and extrafloral nectaries (EFNs) as a mutualism and over 100 years of studies on ant benefits to plants, the benefits to ants have never been experimentally quantified. The success of invasive ants is thought to be linked to the availability of carbohydrate-rich resources, though reports of invasive ant visits to EFNs are mixed. In two laboratory experiments, we compared worker survival of one native (Iridomyrmex chasei) and two invasive ant species (Linepithema humile and Pheidole megacephala) exposed to herbivorized or non-herbivorized EFN-bearing plants (Acacia saligna) or positive and negative controls. We found that non-herbivorized plants did not produce any measurable extrafloral nectar, and ants with access to non-herbivorized plants had the same survival as ants with access to an artificial plant and water (unfed ants). Ants given herbivorized plants had 7-11 times greater worker survival relative to unfed ants, but there were no differences in survival between native and invasive ants exposed to herbivorized plants. Our results reveal that ants cannot induce A. saligna extrafloral nectar production, but workers of both native and invasive ant species can benefit from extrafloral nectar as much as they benefit from sucrose.
Restoration needs to consider more than just soils and plants. The role of terrestrial invertebrates in the restoration of Alcoa's bauxite mines in the Jarrah (Eucalyptus marginata) forest of Western ...Australia has been the subject of over 20 individual studies. Projects range from arthropods in soil and leaf litter, to the understorey vegetation, and the tree canopy. Moreover, projects span a range of trophic groups, including decomposers (e.g., springtails and termites), predators (e.g., ants and spiders), and herbivores (e.g., true bugs and ants preying on seeds). Elucidation of recolonization trajectories uses both space-for-time substitutions and long-term regular sampling. Importantly, many studies are at species level rather than coarser taxonomic ranks. This paper provides an historical account and an integrated review of this research. The role of ants as seed predators and as indicators of ecosystem health is described. Successional data for other groups, when measured by species richness (ants, spiders, and hemipterans) and composition (ants and spiders), show their reassembly trajectories tracking toward unmined reference areas. Hemipteran species composition tracks the vegetation reassembly trajectory but not toward unmined reference areas. Studies also have revealed optimal sampling methods for surveying invertebrates and their rich biodiversity in southwestern Australia. In restored mine pits burnt to reduce fuel loads, the response of spiders to this additional disturbance was retrogression/alteration of the post-mining trajectory. Finally, attention is drawn to research areas receiving limited scrutiny to date, such as the contribution of terrestrial invertebrates to ecosystem function and taxonomic groups not yet studied.
Insects, particularly ants, are good bioindicators of the state of ecosystems. Nevertheless, incorporating them into conservation surveys is expensive due to problems associated with their ...identification, which is exacerbated by the fact that there are fewer and fewer taxonomists working today. “Taxonomic sufficiency” (TS), which identifies organisms to a level of taxonomic resolution sufficient enough to satisfy the objectives of a study, has never been applied to Neotropical ant communities. We analysed five Neotropical datasets representing ant assemblages collected with different sampling methods in various habitats. We first treated them using two complementary and cumulative TS methods, higher-taxon and “indicator taxa” surrogacies, before testing a new approach called “mixed-level method” that combines the two previous approaches. For the higher-taxon surrogacy, we showed that, above species, genus is the most informative taxonomic level. Then, mixed-level method provided more information on ant assemblages than did the two others, even though the “indicator taxa” surrogacy was based on relevant indicator genera. Although habitat type has no effect on its efficiency, this new method is influenced by the dataset structure and the type of sampling method used to collect data. We have thus developed a new method for analyzing Neotropical ant faunas that enables the taxonomic work linked to the identification of problematic species to be significantly reduced, while conserving most of the information on the ant assemblage. This method should enhance the work of Neotropical entomologists not specialised in taxonomy, particularly those concerned with biological conservation and indication.
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