Ant Assemblages Research Articles

Spatial and temporal distribution patterns of ants (Hymenoptera: Formicidae) in Gobi Desert ecosystems, Northwest China

Ants (Hymenoptera: Formicidae) represent the most critical arthropod community in desert ecosystems, where interactions among vegetation, soil, and climate dictate ant assemblages. Nonetheless, our understanding of how various factors influence desert ant assemblages across different spatial and temporal scales remains limited. Therefore, this study aims to analyse the temporal and spatial distribution patterns of desert ants and to determine the effects of precipitation and temperature variations on ant assemblages. To achieve this, we continuously monitored the monthly dynamics of ants at 72 uniform 8m × 8m grid points in the Gobi Desert ecosystem of Northwest China from 2015 to 2020 using pitfall traps. The results indicated that Messor desertus and Cataglyphis aenescens were the dominant ant species, with significant annual and monthly variations in the number of individuals captured from 2015 to 2020. In 2020, monthly captures of M. desertus exhibited a bimodal pattern, peaking in November, whereas those of C. aenescens exhibited a unimodal pattern, peaking in June. Annual data revealed that population size was significantly positively correlated spatially at a distance of 24 meters. Semi-variance analysis and Moran’s I indicated that structural factors predominantly controlled the ant assemblages at a small scale from 2015 to 2020. Annual catches of desert ants tended to decrease with increasing annual precipitation, while an opposite trend was rising average annual temperatures. In conclusion, variations in annual and monthly precipitation and temperature influenced the temporal response patterns of desert ants, thereby altering their spatial assemblages.

The impacts of fire vary among vertical strata: Responses of ant communities to long-term experimental burning.

Fire is a powerful tool for conservation management at a landscape scale, but a rigorous evidence base is often lacking for understanding its impacts on biodiversity in different biomes. Fire-induced changes to habitat openness have been identified as an underlying driver of responses of faunal communities, including for ants. However, most studies of the impacts of fire on ant communities consider only epigeic (foraging on the soil surface) species, which may not reflect the responses of species inhabiting other vertical strata. Here, we examine how the responses of ant communities vary among vertical strata in a highly fire-prone biome. We use a long-term field experiment to quantify the effects of fire on the abundance, richness, and composition of ant assemblages of four vertical strata (subterranean, leaf litter, epigeic, and arboreal) in an Australian tropical savanna. We first document the extent to which each stratum harbors distinct assemblages. We then assess how the assemblage of each stratum responds to three fire-related predictors: fire frequency, fire activity, and vegetation cover. Each stratum harbored a distinct ant assemblage and showed different responses to fire. Leaf litter and epigeic ants were most sensitive to fire because it directly affects their microhabitats, but they showed contrasting negative and positive responses, respectively. Subterranean ants were the least sensitive because of the insulating effects of soil. Our results show that co-occurring species of the same taxonomic group differ in the strength and direction of their response to fire depending on the stratum they inhabit. As such, effective fire management for biodiversity conservation should consider species in all vertical strata.

Temporal and trophic niche partitioning among arboreal ants in a Neotropical woodland savanna

Abstract Niche partitioning is a key mechanism for explaining species coexistence, including the coexistence of ants in trees of the Brazilian savanna (cerrado). However, we have limited information on the extent to which arboreal ant species exploit different food resources and/or have different daily foraging schedules. We tested these ideas through a baiting experiment, and by measuring the isotopic signature (δ15N) and the critical thermal maximum (CTmax) of the 14 most common species found in a typical cerrado tree species. Although most species foraged on all bait types offered, species‐specific preferences were noted for about one‐third of the species. We also found a wide variation in mean δ15N between species, reflecting interspecific differences in trophic position. Most (71.4%) species foraged predominantly on a given period of the day, ranging from strictly nocturnal species to those that foraged mainly in the afternoon. Species with a higher heat tolerance (higher CTmax) often foraged at warmer periods of the day than those with a lower tolerance. Despite the evidence of trophic and temporal niche partitioning, other mechanisms, such as nesting site specialization and behavioural trade‐offs, are required to explain species coexistence in this arboreal ant assemblage, as several species pairs largely overlapped both in their diet and time of foraging. Importantly, our results provide additional support for the idea that physiological restriction to high temperatures is important for understanding interspecific differences in foraging activity schedules.

Ant (Hymenoptera: Formicidae) assemblages in seashore vegetation (“restinga”) formations along the northern coast of the state of Bahia, Brazil

Ant (Hymenoptera: Formicidae) assemblages in seashore vegetation (“restinga”) formations along the northern coast of the state of Bahia, Brazil

The Effects of Fire on Ant Assemblages are Stratum‐Specific

The Effects of Fire on Ant Assemblages are Stratum‐Specific

Reassembly of ground-dwelling ant communities in reforestation plots in SW Costa Rica

Due to agriculture and logging, Costa Rica has lost many primary forests, making reforestation an important task. To judge the progress of reforestation, it is important to follow the reassembly of organismal communities within restored habitats. The COBIGA project near La Gamba, in the Golfo Dulce region of Costa Rica, aims at reforestation of lowland sites with native tree species. Ants, as ubiquitous and highly abundant terrestrial organisms, have a substantial influence on tropical ecosystems. The multiple roles include scavenging, predation, herbivory, and mutualistic interactions. We examined ant community responses to reveal the status of community regeneration and functional integrity. We compared the composition and diversity of the ant assemblages at three different age reforestation sites (2, 8, and 10 years old) with those at an old-growth forest as a reference site. By offering canned tuna fish at ground level along replicated transects, we observed 43 ant species representing six functional groups during the 2 months of sampling. Most of the observed ant species were omnivorous, but old-growth forests harbored a substantial number of other functional groups, such as generalized predators, arboreal predators, and arboreal omnivores. In contrast, the youngest reforestation site harbored a severely impoverished ant assemblage comprising mostly generalized polygynous and polydomous ant species from lower trophic levels. The within-site heterogeneity of the ant assemblages increased from the youngest to the oldest forest. In addition, our results show the importance of monitoring the progress of forest recovery to avoid the spread of invasive species into primary habitats.

Structure of ant assemblages and effect of environmental conditions in gallery forests with different conservation status in the Humid Chaco ecoregion of Argentina

Structure of ant assemblages and effect of environmental conditions in gallery forests with different conservation status in the Humid Chaco ecoregion of Argentina

Beyond beta: diversity partitioning reveals different underlying patterns in ant assemblages along two small scale gradients in a Brazilian neotropical forest

Beyond beta: diversity partitioning reveals different underlying patterns in ant assemblages along two small scale gradients in a Brazilian neotropical forest

Temperature-driven homogenization of an ant community over 60 years in a montane ecosystem.

Identifying the mechanisms underlying the changes in the distribution of species is critical to accurately predict how species have responded and will respond to climate change. Here, we take advantage of a late-1950s study on ant assemblages in a canyon near Boulder, Colorado, USA, to understand how and why species distributions have changed over a 60-year period. Community composition changed over 60 years with increasing compositional similarity among ant assemblages. Community composition differed significantly between the periods, with aspect and tree cover influencing composition. Species that foraged in broader temperature ranges became more widespread over the 60-year period. Our work highlights that shifts in community composition and biotic homogenization can occur even in undisturbed areas without strong habitat degradation. We also show the power of pairing historical and contemporary data and encourage more mechanistic studies to predict species changes under climate change.

A Rapid Sampling of Ant Assemblages Diagnoses Soil Physicochemical Properties before Planting Chayote Monoculture

Ants respond fast to changes in soil conditions in agricultural fields, thus they represent a practical, cheap, clean, and accurate tool to diagnose soil fertility before planting a crop. This study assesses the capacity of richness, occurrence, and activity of ant assemblages to indicate soil physicochemical properties in chayote monoculture in Veracruz, Mexico. Sampling was performed in 15 1-ha-plots and was replicated three times before planting chayote from August to October. Ants were collected using pit-fall traps and determined soil properties were texture, density, contents of organic matter (OM), nitrogen (N), and phosphorous (P), pH, and electrical conductivity (EC). In total, 20,385 ant workers belonging to 51 species, 28 genera, 9 tribes and 6 subfamilies were collected. Species richness significantly explained contents of OM, N, and P in a three-weeks sampling. Species occurrence explained clay percentage in the one-week sampling, N, and P contents in the two-weeks sampling and the aforementioned and percentages of sand and silt in the three-weeks sampling. Ant activity predicted more soil properties in the one-week sampling than in those that lasted two and three weeks.Richness, occurrence, and activity of ant assemblages are valuable tools for diagnosing texture, contents of OM, N, and P, and pH of soil before planting chayote monoculture. It contributes to the understanding of the role that ants play in agricultural fields. Therefore, soil management practices should consider indication capacity of ant assemblages to ensure growth and development of morphological structures such roots, stems, leaves, shoots, and fruits of cultivated plants.

Non-native ants are breaking down biogeographic boundaries and homogenizing community assemblages

As geographic distance increases, species assemblages become more distinct, defining global biogeographic realms with abrupt biogeographic boundaries. Yet, it remains largely unknown to what extent these realms may change because of human-mediated dispersal of species. Focusing on the distributions of 309 non-native ant species, we show that historical biogeographic patterns have already broken down into tropical versus non-tropical regions. Importantly, we demonstrate that these profound changes are not limited to the distribution patterns of non-native ants but fundamentally alter biogeographic boundaries of all ant biodiversity (13,774 species). In total, 52% of ant assemblages have become more similar, supporting a global trend of biotic homogenization. Strikingly, this trend was strongest on islands and in the tropics, which harbor some of the most vulnerable ecosystems. Overall, we show that the pervasive anthropogenic impacts on biodiversity override biogeographic patterns resulting from millions of years of evolution, and disproportionally affect particular regions.

Imprints of indirect interactions on a resource-mediated ant-plant network across different levels of network organization.

Indirect interactions are pivotal in the evolution of interacting species and the assembly of populations and communities. Nevertheless, despite recently being investigated in plant-animal mutualism at the community level, indirect interactions have not been studied in resource-mediated mutualisms involving plant individuals that share different animal species as partners within a population (i.e., individual-based networks). Here, we analyzed an individual-based ant-plant network to evaluate how resource properties affect indirect interaction patterns and how changes in indirect links leave imprints in the network across multiple levels of network organization. Using complementary analytical approaches, we described the patterns of indirect interactions at the micro-, meso-, and macro-scale. We predicted that plants offering intermediate levels of nectar quantity and quality interact with more diverse ant assemblages. The increased number of ant species would cause a higher potential for indirect interactions in all scales evaluated. We found that nectar properties modified patterns of indirect interactions of plant individuals that share mutualistic partners, leaving imprints across different network scales. To our knowledge, this is the first study tracking indirect interactions in multiple scales within an individual-based network. We show that functional traits of interacting species, such as nectar properties, may lead to changes in indirect interactions, which could be tracked across different levels of the network organization evaluated.

Habitat simplification affects functional group structure along with taxonomic and phylogenetic diversity of temperate‐zone ant assemblages over a ten‐year period

Biodiversity is declining at various scales due to habitat simplification. Nevertheless, there is scarce information on how the biotic and abiotic changes linked to simplification affect several diversity dimensions, such as taxonomic, functional, and phylogenetic diversities. This study investigated whether transforming natural oak forests into induced grasslands affected species diversity, functional group structure, and phylogenetic diversity of ant assemblages inhabiting a temperate forest in central Mexico. We placed over 1000 pitfall traps in five sampling events covering a ten‐year period. We used Hill numbers to evaluate species diversity differences between vegetation types and patterns over time. Ant species were classified into stress‐related functional groups, which were analyzed for their association with vegetation types and changes to their proportional abundance over time. We calculated the standardized effect size of the mean nearest taxon distance to quantify the evolutionary history and test for non‐random patterns within vegetation types and sampling years. Species richness did not differ between vegetation types, yet grasslands showed greater diversity for the q = 1 and q = 2 orders. , We also found three ant species as bioindicators for each type of vegetation. Regarding functional structure, cold climate specialists were associated with oak forests. In contrast, generalist species were predominant in induced grasslands. Higher phylogenetic diversity with an overdispersed structure was associated with oak forest, whereas lower phylogenetic diversity and a clustered pattern were found in induced grassland. These results indicate that habitat simplification may not affect the number of ant species, but rather increases their relative abundance and reorganizes the functional and phylogenetic structure in the ecosystem, particularly shifting towards the dominance of evolutionary closely related species and broad‐stress‐tolerant groups. These results highlight the importance of integrating further dimensions of diversity to properly evaluate the reassembly dynamics after habitat simplification, and understand the mechanisms driving this biodiversity loss.

Rates of species turnover across elevation vary with vertical stratum in rainforest ant assemblages

Climatic variation at local scales can influence both exposure and sensitivity of organisms and thereby scale up to influence population persistence and community composition across broader geographic extents. Tropical forest canopies are more climatically dynamic than the understorey. Consequently, the niche space of forest canopies has higher overlap in thermal conditions along elevation gradients, which imposes less of a climatic barrier to arboreal species than their ground‐dwelling counterparts. We use ant communities of the Australian Wet Tropics to test the prediction that ground communities should have higher rates of species turnover over elevation compared to arboreal communities. We sampled ground and arboreal ants along elevation gradients at a bioregional scale that includes four mountain sub‐regions. We assessed community composition at three spatial resolutions (regional, elevation, vertical) and then calculated beta diversity (species turnover) over elevation for ground and arboreal communities using null modelling procedures to compare different sized species pools. Vertical niche affinity was a strong contributor to overall biogeographic patterns; indicated by a strong interaction between vertical niche and elevation in beta diversity models. On average, the ground community exhibited a pronounced elevational distance–decay pattern while the arboreal community showed no pattern. Mean species turnover was 36% higher in ground than arboreal communities. Our findings suggest that the vertical niche has a pronounced effect on biogeographic patterns which has important implications for understanding the role of local scale climate conditions in shaping communities and for potential responses to future climate change.

Inventaire des fourmis de l’île d’Yeu (France) (Hymenoptera, Formicidae)

Inventory of ants of the Yeu Island (France) (Hymenoptera, Formicidae). Yeu is a small island located in the Bay of Biscay that encompasses a wide diversity of highly preserved coastal habitats. We provide here a first formal inventory of the ant community found on the island, where we identified 29 species forming an assemblage of temperate and Mediterranean ants at the northern range of their distribution. The presence of species such as Messor capitatus, Aphaenogaster gibbosa and Monomorium carbonarium is discussed, as well as the occurrence of species seldom observed across the western part of France such as Strongylognathus testaceus and Lasius mixtus. Considering the overall remarkable diversity found on the island given its minute size, we further provide a detailed list of the species found at the surveyed sites, as well as brief additional notes on their ecology.

Regionally unique ant assemblages associated with community‐based conservation in northwestern Ghana

AbstractCommunity‐based conservation can play an important role in preserving biodiversity, but it is unclear whether such benefits extend to invertebrate communities; in particular, baseline data for insect communities is lacking to assess efficacy of conservation efforts. Here we evaluate ant assemblages across three habitats, protected within the Wechiau Community Hippo Sanctuary (WCHS) in the Upper West Region of Ghana. We compare relative ant species diversity and uniqueness between the sanctuary's Guinea savannah, riparian forest, and floodplain habitats. Ants were collected with other invertebrates using malaise traps, pitfall traps, and yellow pan traps between 2001 and 2011 multiple times per year. From these data, we compiled a list of ant species found, castes collected, and functional groups, and evaluated the differences in ant diversity among the habitats using accumulation curves, assemblage structure comparison, and Morisita‐Horn indices. We also compared the overall WCHS assemblage to other ant assemblages in Western Africa to gain a clearer understanding of relative diversity and uniqueness. We collected 83 species from seven subfamilies and 44 genera; 14 of the species were previously unrecorded in Ghana, including one ant species new to science. Ant species diversity differed among habitats in assemblage composition but not significantly in species richness. We found that the WCHS ant assemblage was relatively unique, sharing only about 35% of species found in similar Côte d'Ivoire habitats, and 25% of other Ghanaian assemblages. Some species present in the WCHS were not found in any of the other compared assemblages. We conclude that community‐based conservation initiatives like the WCHS may play an important role in conserving the biodiversity of ants.

Selection of climate variables in ant species distribution models: case study in South Korea.

The selection of explanatory variables is important in modeling prediction of changes in species distribution in response to climate change. In this study, we evaluated the importance of variable selection in species distribution models. We compared two different types of models for predicting the distribution of ant species: temperature-only and both temperature and precipitation. Ants were collected at 343 forest sites across South Korea from 2006 through 2009. We used a generalized additive model (GAM) to predict the future distribution of 16 species that showed significant responses to changes in climatic factors (temperature and/or precipitation). Four types of GAMs were constructed: temperature, temperature with interaction of precipitation, temperature and precipitation without interaction, and temperature and precipitation with interaction. Most species displayed similar results between the temperatureonly and the temperature and precipitation models. The results for predicted changes in species richness were different from the temperature-only model. This indicates higher uncertainty in the prediction of species richness, which is obtained by combining the prediction results of distribution change for each species, than in the prediction of distribution change. The turnover rate of the ant assemblages was predicted to increase with decreases in temperature and increases in elevation, which was consistent with other studies. Finally, our results showed that the prediction of the distribution or diversity of organisms responding to climate change is uncertain because of the high variability of the model outputs induced by the variables used in the models.

One ant's trash is another ant's treasure: Army ant middens provide resources for diverse ant assemblages

AbstractThe army ant Eciton burchellii boasts more animal associates than any other animal species yet described, but the relationship between army ants and other ant species has only been studied in the context of predation. The waste deposits (middens) of army ant colonies are nitrogen‐rich, a potentially high‐value nutrient source for leaflitter arthropods. We explored this bottom‐up role of army ant middens in the context of tropical ant communities. Our three main questions were the followings: (1) Which ant species forage on army‐ant middens? (2) How does the bi‐phasic life cycle of army ant colonies (affecting midden size, persistence, and abundance) affect which and how many ant species a midden boasts? (3) How do the ants that forage on army ant middens differ across elevations? Across 39 bivouacs, we found 36 species of ants foraging on army ant middens. These included highly predatory ants, nitrogen‐limited arboreal ants, and fungus‐farming ants. Per‐midden richness was significantly lower for the usually smaller middens deposited during the nomadic phase and was higher for the typically larger middens deposited during the statary phase. Per‐midden richness was not significantly different across elevations, but there was far greater species turnover across elevations than across phases within the same elevational site. Our results suggest that army ant middens are an important resource for a wide variety of tropical ants, informing a better understanding of the complex network of associations revolving around this keystone species.Abstract in Spanish is available with online material

Complexity of cacao production systems affects terrestrial ant assemblages

Given the rapid changes in tropical agricultural production, the evaluation of different management practices has gained interest to determine the effects of land-use change on biodiversity. The conversion of forests into agricultural land is one of the main drivers of diversity loss. Agroforestry systems have been shown as a promising option to provide suitable yields in addition to conserving biodiversity. In this study we compared species richness and community composition of terrestrial ants in six different systems in a long-term experimental site established in 2009 in Bolivia: a full-sun monoculture and an agroforestry system under conventional management, a full-sun monoculture and an agroforestry system under organic management, a highly diverse and dense agroforestry system without external inputs and a secondary forest. Using pitfall traps, we sampled ants four times during a seven-year period (2015-2021). We collected a total of 85 ant species belonging to 6 sub-families and 41 genera. More than 80% of the species were recorded in less than 10% of the traps. Species richness did not significantly differ between the systems. However, species composition mainly differed between the fallow and the production systems, and within the latter, it followed the management intensity gradient, i.e., complex agroforestry, agroforestry and monocultures. The indicator species analysis clearly showed species exclusively associated with one or more production systems, whereas others were only associated with the secondary forest. Species with specialised trophic roles were more frequent in forest and agroforestry systems. Our results showed that the disturbance generated by cultivation was the main driver differentiating ant communities, but also reinforced the importance of the complexity and management intensity of the production system. These results have strong implications for landscape management and highlights the importance of preserving natural patches of forest but also diverse and complex agroforestry systems within the agricultural matrix for ant diversity conservation.

Competition and habitat availability interact to structure arboreal ant communities across scales of ecological organization.

Understanding how resource limitation and biotic interactions interact across spatial scales is fundamental to explaining the structure of ecological communities. However, empirical studies addressing this issue are often hindered by logistical constraints, especially at local scales. Here, we use a highly tractable arboreal ant study system to explore the interactive effects of resource availability and competition on community structure across three local scales: an individual tree, the nest network created by each colony and the individual ant nest. On individual trees, the ant assemblages are primarily shaped by availability of dead wood, a critical nesting resource. The nest networks within a tree are constrained by the availability of nesting resources but also influenced by the co-occurring species. Within individual nests, the distribution of adult ants is only affected by distance to interspecific competitors. These findings demonstrate that resource limitation exerts the strongest effects on diversity at higher levels of local ecological organization, transitioning to a stronger effect of species interactions at finer scales. Collectively, these results highlight that the process exerting the strongest influence on community structure is highly dependent on the scale at which we examine the community, with shifts occurring even across fine-grained local scales.