Ant Composition Research Articles

Can variation in seed removal patterns of Neotropical pioneer tree species be explained by local ant community composition?

AbstractMany plants depend on animals for seed dispersal, and ants commonly fill this role. We examined whether heterogeneity in ant community composition among sites, between above‐ and belowground foraging guilds, or between seasons predicts observed variation in seed removal rates for 12 nonmyrmecochorous Neotropical pioneer tree species on Barro Colorado Island, Panama. We also investigated whether ants associated with removing seeds differed in specific morphological characters from the larger ant community. We observed ant–seed interactions at caches to determine which ants removed seeds of 12 tree species. We also sampled ant community composition by placing 315 pitfall traps and 160 subterranean traps across the five sites where seed removal rates were quantified. Aboveground ant community composition varied by site but not season. Among‐site variation in ant composition did not predict seed removal patterns at these same sites. Belowground ant communities differed from aboveground ant communities but were not structured by either site or seed cache type. Finally, ants that removed seeds did not differ morphologically from the broader ant community. Overall, our results suggest ant communities vary over relatively small spatial scales but exhibit a high degree of functional redundancy in terms of seed removal services provided for Neotropical pioneer tree species.Abstract in Spanish is available with online material.

Effect of forest disturbance on ant (Hymenoptera: Formicidae) diversity in a Mexican tropical dry forest canopy

Abstract1. Ants are the dominant insects in tropical forest canopies. The α and β diversities of ants change in response to forest disturbance. Understanding the response of ants to forest disturbance will help to guide ant conservation and forest management plans, especially in endangered ecosystems such as the tropical dry forest. 2. We analysed ant α and β diversities in 15 fragments (5 mature, 5 disturbed, and 5 secondary) of a tropical dry forest in central Mexico. We identified and measured all of the trees in two transects (10 × 50 m) established within each fragment. Pit‐fall traps were used to sample ants in all of the trees. 3. We identified 52 ant species (from a total of 11,524 individuals). The mature forest presented the greatest quantity of exclusive species and the highest α diversity. Ant composition differed among the mature forest but not between disturbed and secondary forest, and was related to tree size and richness. The β diversity was lower in the disturbed forest, reflecting the cost of biotic homogenization (15%). Among the β diversity components in all three forest types, this diversity was mainly influenced by turnover, while nestedness diminished in the disturbed forest. 4. In the tropical dry forest studied, anthropogenic disturbance homogenises the ant community, probably because the availability of resources is also homogenised, decreasing the α diversities of the canopy ants. Our results show the importance of the conservation of mature forests in terms of maintaining the diversity of canopy ants.

Environmental determinants of leaf litter ant community composition along an elevational gradient

AbstractAnt communities are extremely diverse and provide a wide variety of ecological functions in tropical forests. Here, we investigated the abiotic factors driving ant composition turnover across an elevational gradient at Mont Itoupé, French Guiana. Mont Itoupé is an isolated mountain whose top is covered by cloud forests, a biogeographical rarity that is likely to be threatened according to climate change scenarios in the region. We examined the influence of six soil, climatic, and LiDAR‐derived vegetation structural variables on leaf litter ant assembly (267 species) across nine 0.12‐ha plots disposed at three elevations (ca. 400, 600, and 800m asl). We tested (a) whether species cooccurring within a same plot or a same elevation were more similar in terms of taxonomic, functional, and phylogenetic composition, than species from different plots/elevations, and (b) which environmental variables significantly explained compositional turnover among plots. We found that the distribution of species and traits of ant communities along the elevational gradient was significantly explained by a turnover of environmental conditions, particularly in soil phosphorus and sand content, canopy height, and mean annual relative humidity of soil. Our results shed light on the role exerted by environmental filtering in shaping ant community assembly in tropical forests. Identifying the environmental determinants of ant species distribution along tropical elevational gradients could help predicting the future impacts of global warming on biodiversity organization in vulnerable environments such as cloud forests.

Peace, sweet peace: ants become less aggressive when carbohydrates abound

1. An animal's energetic condition is causally related to its ability to display costly behaviours such as aggressive behaviours. Aggressive behaviours are used by animals interacting with heterospecifics when competing through interference. Therefore, how does the abundance of energetic resources influence the pattern of interspecific competition by interference at the community level? To answer this, ants were used as models because the aggressiveness of workers is fuelled by the consumption of carbohydrates.2. It was hypothesised that ant species are more aggressive when carbohydrates were more abundant. Consequently, the strength of competition by interference would increase, changing the patterns of ant species' resource use at the community level.3. This study experimentally increased the availability of carbohydrates and counted the number of aggressive behaviours, the probability of ant species exclusion, and the composition of ant morphospecies exploring protein baits before and after the addition of carbohydrates.4. After the addition of carbohydrates, ants displayed 42% less aggressive behaviour and were twice as prone to exclude other ant species from the protein baits. This led to changes in the composition of ants exploring the protein baits before and after carbohydrate addition.5. In general, ants became less motivated to engage in competitive interactions when carbohydrates were more available. However, this response was not homogeneous as the occurrence and aggressiveness of some species, such as the nectarivores, were higher when carbohydrates abound. As carbohydrates are mainly offered by plants, this study's results suggest that plants can indirectly shape the structure of ant communities through ant responses to the availability of carbohydrates.

Contrasting effects of herbivore damage type on extrafloral nectar production and ant attendance

The ant-plant mutualism mediated by extrafloral nectaries (EFNs) is based on the provision of extrafloral nectar (a sugar-rich liquid) in exchange for ant defense against herbivores. The extrafloral nectar production can vary depending on the intensity or types of leaf damage caused by different mouthparts of insect herbivores (i.e., sucking or chewing insects). However, it is poorly known how the type of herbivore damage changes the outcomes of tri-trophic interactions. Here, we address how the damage inflicted by different herbivore groups affects extrafloral nectar production and ants’ attendance and aggressiveness. Through an experimental field study, we tested whether the type of leaf damage, sucking or chewing, changes extrafloral nectar volume and sugar concentration, and subsequently ant composition and behavior. We evaluated the extrafloral nectar production and ant attendance and aggressiveness before and after simulated herbivory in Qualea parviflora (Vochysiaceae), a Brazilian savanna EFN-bearing plant. We found that only plants with sucking damage increased the sugar concentration of their extrafloral nectar, only plants with chewing damage increased ant abundance, and surrogate herbivore predation differed before and after simulated herbivory only for sucking damage. We provided the first evidence that the type of damage can influence ant aggressiveness via changes in extrafloral nectar production, translating to changes in the outcomes of this ant-plant mutualism. Ultimately, studies should consider the effects of herbivore damage type when studying insect-plant interactions.

Comparative FISH-mapping of TTAGG telomeric sequences to the chromosomes of leafcutter ants (Formicidae, Myrmicinae): is the insect canonical sequence conserved?

Telomeric sequences are conserved across species. The most common sequence reported among insects is (TTAGG)n, but its universal occurrence is not a consensus because other canonical motifs have been reported. In the present study, we used fluorescence in situ hybridization (FISH) using telomeric probes with (TTAGG)6 repeats to describe the telomere composition of leafcutter ants. We performed the molecular cytogenetic characterization of six Acromyrmex Mayr, 1865 and one Atta Fabricius, 1804 species (Acromyrmex ambiguus (Emery, 1888), Ac. crassispinus (Forel, 1909), Ac. lundii (Guérin-Mèneville, 1838), Ac. nigrosetosus (Forel, 1908), Ac. rugosus (Smith, 1858), Ac. subterraneus subterraneus (Forel, 1893), and Atta sexdens (Linnaeus, 1758)) and described it using a karyomorphometric approach on their chromosomes. The diploid chromosome number 2n = 38 was found in all Acromyrmex species, and the karyotypic formulas were as follows: Ac. ambiguus 2K = 14M + 12SM + 8ST + 4A, Ac. crassispinus 2K = 12M + 20SM + 4ST + 2A, Ac. lundii 2K = 10M + 14SM + 10ST + 4A, Ac. nigrosetosus 2K = 12M + 14SM + 10ST + 2A, and Ac. subterraneus subterraneus 2K = 14M + 18SM + 4ST + 2A. The exact karyotypic formula was not established for Ac. rugosus. FISH analyses revealed the telomeric regions in all the chromosomes of the species studied in the present work were marked by the (TTAGG)6 sequence. These results reinforce the premise that Formicidae presents high homology between their genera for the presence of the canonical sequence (TTAGG)n.

Fatores associados à ocorrência de formigas em escolas urbanas

As escolas consistem em ambientes que oferecem condições favoráveis para acolonização por formigas. Este estudo objetiva identificar os fatores associadosà ocorrência de formigas em quatro ambientes escolares localizados em áreasurbanas. A amostragem foi realizada em cozinhas, almoxarifados, refeitóriose áreas externas em doze escolas de quatro municípios da região oeste doestado de Santa Catarina, Brasil. Foram utilizadas iscas e coleta manual naamostragem. Variáveis ambientais foram obtidas em cada local. A similaridadeentre as amostras quanto à composição e a abundância de formigas foiavaliada por meio de uma escala multidimensional não métrica (non-metricmultidimensional scaling — NMDS). Foram amostrados 1.478 exemplaresde formigas e identificados 45 espécies. Foi observada uma similaridade de60% na abundância e composição das assembleias de formigas entre escolasde pequenas cidades (Caxambu do Sul, Guatambú e Palmitos). A presençade áreas externas com vegetação e áreas verdes no entorno, o tamanho daárea construída e a frequência de eventos de controle de insetos contribuempara a abundância desses insetos nos ambientes escolares. As formigas nãosão reconhecidas como potenciais vetores de micro-organismos patogênicosnas escolas e são negligenciadas se considerada a periodicidade do controlede insetos.

INFLUENCE OF THE CEMENT DUST ON ANTS GROUPING (HYMENOPTERA, FORMICIDAE)

Introduction. Industrial emissions affect the impoverishment of insect fauna not only by reducing their species composition but also by reducing the abundance of dominant species.Aim. Therefore, the goal of the research was to investigate how the cement dust affects species diversity of ants, density and types of anthills.Methods. Investigation of the effect of cement dust on mirmecofauna was carried out on the territory of village Yamnytsia, Tysmenytsia district, Ivano-Frankivsk region and its vicinity, near the cement plant of PJSC «Ivano-Frankivskcement». Meadows and deciduous forests were studied within the village of Yamnytsia, which are located at different distances from the source of cement dust (0; 0.5 km; 1 km; 5.5 km) and 30 km from the village boundary (control). To quantify the species composition of Formica ants, the methods of K. V. Arnoldi were used. Counting of anthills and sampling of ants was performed according to the method of G. M. Dlussky. Anthills were described by the standard method, the account of the building material of the nests was carried out visually, the material was not selected.Results. Analyzing the distribution of ants genera and species on the experimental meadows, we found a direct correlation between the number of ants and the distance from the sources of cement dust (r=0.87 at p<0.05). The largest number of the ant species was observed in the area of influence from the genus Lasius. Myrmica nests are found not closer than 1 km from PJSC «Ivano-Frankivskcement», Formica nests are only in the control. With a decrease in the pollution degree, the proportion of underground nests increases (r=0.90 at p<0.05), the proportion of the dome nests decreases (r=-0.94 at p<0.05). At the same time, the size of dome on average decreases when the distance from the source of pollution grows. All anthills registered in the most polluted zone consist of a mixture of cement dust and earth up to 45 cm high. About 75 % of all nests found were heavily overgrown. Adaptation of the ants to the influence of cement dust differs from other types of impact and is expressed in the fact that in technogenic territories anthills are more often dome-shaped, of smaller diameter and considerably higher than those located in the control zone. This is because the soil near PJSC «Ivano-Frankivskcement» is covered with a layer of the lime dust which reaches 5 cm. Lasius niger is resistant to various forms of the anthropogenic influence, which can be explained by the adaptive features of the anthill forms.Conclusion. Under the influence of emissions from PJSC «Ivano-Frankivskсement», the anthill density of Formica genera is greatly reduced and is dominated by ants of the genera Lasius and Myrmica. The height of the L. niger anthill is inversely proportional to the distance to the source of industrial emissions, and the frequency of occurrence of underground nests of most species is directly proportional to the degree of anthropogenic impact.Keywords: ants; anthropogenic influence; cement dust; Lasius; Myrmica.

Relação entre a circunferência da árvore e a comunidade de formigas (Hymenoptera: Formicidae) arborícolas em uma área de preservação amazônica

Mecanismos responsáveis pela coexistência de espécies no ambiente têm implicações consideráveis na estruturação da fauna local. Aqui, avaliamos a estrutura da comunidade de formigas em uma área de floresta amazônica preservada, utilizando a circunferência das árvores como um parâmetro de heterogeneidade ambiental. Para isso, selecionamos 29 árvores, com diferentes circunferências a altura do peito (de 11 a 234 cm), e capturamos as formigas que utilizam esse substrato através de pitfalls com urina humana. Encontramos 30 espécies de formigas, mas riqueza e composição não foram influenciadas pela circunferência das árvores. Fatores combinados e mais diretamente associados à heterogeneidade ambiental, como a conectividade das árvores, devem ser levados a efeito, a fim de que tenhamos conhecimento sobre os impulsionadores locais de diversidade no estrato vertical de remanescentes amazônicos preservados.

Interactive effects of urbanization and year on invasive and native ant diversity of sacred groves of South India

Urbanization is a major threat to native biodiversity. Invasion of tramp species is a major consequence of urbanization, which might threaten native species. Ants are established robust ecosystem indicators. We assessed the changes of ant community in sacred groves (SGs) of urban and rural landscapes of south India between 2013 and 2019, and asked, 1) what is the effect of urbanization on ant community? 2) has the population of invasive ants, particularly Anoplolepis gracilipes – a globally notorious tramp species, changed in response to urbanization and year? 3) is species composition of ants in SGs different between landscapes and years? and 4) has the population of native ants or any ant functional groups responded with the population of invasive ants? The richness of overall species, native species, and invasive species was not affected by year or landscape, but the abundance was. In six years, the abundance of ants doubled, but due to A. gracilipes. A. gracilipes, previously restricted only in the urban SGs had established in rural SGs in six years. A significant turnover of native species was observed across years and with the population rise of A. gracilipes. While Generalist Myrmecines and Tropical Climate Specialists increased with the abundance of invasive ants, Cryptic Species decreased. We consider the stability maintained in the native species composition and richness in SGs, the aftermath of the conditions provided by SGs. However, the evident shift in the composition of native ants over the years point out how invasive ants affect the native species composition.

Impacts of Tractor Logging on the Diversity of Ground Ants (Hymenoptera: Formicidae) in Natural Production Forest of Central Borneo

Tractor logging in tropical forest concession disturbs the life of soil surface organisms, including ground ant. Ground ant has an important role in determining soil fertility. The study aimed to analyze the impact of tractor logging on the diversity of ground ant (Hymenoptera, Formicidae) in the natural production forest. Two transect lines of 100 m length and 200 m distance between lines were placed in four different cutting compartments, i.e., currently logged, one month after logging, two months after logging, and unlogged. Ground ant was collected using a pitfall trap. The environmental factors (density of understorey plants, canopy cover, soil compaction, litter thickness, temperature, and humidity) were measured at the setting location of pitfall trap. Analysis of variance (ANOVA) was used to determine the mean difference between treatments. Pearson correlation test was used to determine the correlation between insect abundance and environmental factors. The results of the study indicated that there was a significant difference in the abundance of the ground ant after logging and before logging. The abundance of ground ants after logging was lower than before logging. The abundance of ground ants among skidded plots was not significantly different. Soil compaction due to tractor logging, litter thickness, and temperature did not significantly affect the abundance of ground ants. The ground ant composition did not change due to tractor logging.Keywords: environment impact, forest conservation, forest disturbance, forest ecosystem

Positive and negative impact to decomposition of pig cadavers by ants (hymenoptera: Formicidae) at the Islet Yeongdo in Busan, South Korea

AbstractWe observed how ants affected the decomposition process of pig cadavers. Experiments were carried out with six pig cadavers during three seasons without winter. Fifteen ant species belonging to 14 genera 3 subfamilies were recorded from pig cadavers. The species richness and species composition of ants were different significantly at bloated and decay stages from the remaining stages, regardless of season. Ant species Nylanderia flavipes, Aphaenogaster japonica, Pheidole fervida, and Ectomomyrmex javanus kept hunting a considerable amount of eggs and maggots of flies in the two stages. In particular, Lasius japonicus continually interrupted landing and ovipositing of flies and removed eggs and maggots from pig cadavers. Our observation suggests that ants may affect decomposition process of dead animals by participating in positive and negative ways by massive removal of eggs and maggots of flies.

Ant assemblage composition explains high predation pressure on artificial caterpillars during early night

1. Predator–prey interactions, especially those involving herbivorous insects, are of great importance in maintaining biodiversity. Predation pressure varies temporally in response to prey availability and activity. However, little is known about the patterns and drivers of fluctuations in predation pressure at fine temporal scales.2. Artificial caterpillars (placed on plant leaves at breast height) were used to assess changes in predation pressure across four time intervals of the day in a monsoonal tropical rainforest in south‐west China. The study examined how assemblage composition of arboreal ants, the dominant predators, changed across the same time intervals. The potential linkages between biotic (arboreal ants) and abiotic (temperature and light intensity) factors with predation rate were evaluated.3. Predation rate on caterpillars during the early part of the night (19.00–01.00 hours) was significantly higher than in the morning, afternoon, or late night. Ant assemblage composition, rather than species richness or total abundance, best explained the variations in predation rate on artificial caterpillars.4. The results help to strengthen understanding of trophic interactions by demonstrating that predation pressure fluctuates at finer timescales than previously tested, and that a particular set of ant species may play major roles in predation on caterpillars and possibly other organisms.

Diversity snapshot of green–gray space ants in two Mexican cities

This study evaluates changes in the diversity and composition of ants that inhabit contrasting environmental conditions (green and gray spaces) in two cities of different size and degree of urbanization: Xalapa and Coatepec (Veracruz, Mexico), both of which are surrounded by cloud forest remnants, croplands and pastures. In each city, a green space and a gray space of similar area were selected (~ 31 ha) and ten sampling sites were randomly placed within each environment. Tuna in oil and honey were used as baits to collect soil ants, entomological nets to capture vegetation ants and Winkler sacks for leaf-litter ants. Ant species richness (0D) and diversity (1D) was greater in Coatepec (the smaller and less urbanized city) than in Xalapa. However, the pattern observed when comparing green and gray spaces differed between the cities: the greatest diversity (0D and 1D) was observed in the gray space of Coatepec and the lowest diversity in the green space of Xalapa. In both cities, the similarity of species composition between habitat conditions was close to 50% and the comparison of green spaces between the cities showed that these are more different to each other than is the case with the gray spaces. These results suggest that the characteristics of each city influence the ant diversity contained in green and gray spaces differently and can promote differentiation in species composition within the same city.

Time to go home: The temporal threshold in the regeneration of the ant community in the Brazilian savanna

The aim of this study was to evaluate the influence of succession stages of regeneration of the Brazilian savanna (Cerrado) on the richness, diversity, trophic guilds, and community composition of ants looking for taxonomic and functional changes in the community. The areas included an active pasture that had been created within the past six months, areas with several years of abandonment with different degrees of natural Brazilian savanna regeneration (from 2 to 15 years), and two large remnants of native forest that had been preserved for at least 40 years. Collections were carried out in 56 plots using sardine baits and an active search for a period of one hour in each plot. In addition to calculating the regeneration age, we evaluated successional stages by measuring vegetal characteristics in each plot. A total of 60 species was obtained, distributed in 28 genera and 8 subfamilies, and these demonstrated a direct association with the regeneration age of the areas, as well as their richness and diversity of ants. Areas with initial regeneration showed a greater proportion of generalist species and, as plant succession increased, generalist species decreased. A temporal threshold of 5–6 years for regeneration age was observed, when the community structure tended to stabilize. We observed that the maintenance of a minimum quantity of vegetation in areas destined for livestock can efficiently preserve ant diversity.

Ant assemblage composition and structure in different land uses in Santa Fe de Antioquia, Colombia

The Agrarian Station Cotove is located in Santa Fe de Antioquia, an area of tropical dry forest in which agricultural activities have been carried out for more than 40 years, which have transformed their original ecosystems and modifi ed the environmental conditions. Therefore, this study aims to evaluate the composition and structure of ants in five sites with different land uses: fruit trees, silvopasture, secondary forest, grass for cutting, and pastures with low density of trees. In each land use, three transects of 100m each were located, inside, inside-edge, and edge, taking a sample every 20m to a depth of 10cm. In each site, the ants were identified to morphospecies, and classified by trophic guilds and by functional groups. The diversity index for each land uses were determined. We collected 5239 ants, grouped in 253 colonies, belonging to 23 genera and 37 morphospecies of subfamilies Myrmicinae, Ponerinae, Formicinae y Ecitoninae. Species diversity was highest in secondary forest and fruit trees, while the dominance was higher in silvopasture and pastures with low density of trees. Secondary forest and fruit trees showed the highest value of shared morphospecies. The omnivorous and predator’s trophic guilds were the best represented, and regarding functional groups, we found a high proportion of tropical climate specialists and Myrmicinae generalists.

Experimental effects of white-tailed deer and an invasive shrub on forest ant communities

Ungulate browse and invasive plants exert pressure on plant communities and alter the physical and chemical properties of soils, but little is known about their effects on litter-dwelling arthropods. In particular, ants (Formicidae) are ubiquitous in temperate forests and are sensitive to changes in habitat structure and resources. As ants play many functional roles, changes to ant communities may lead to changes in ecosystem processes. We conducted a long-term experiment that controlled white-tailed deer (Odocoileus virginianus) access and presence of an invasive understory shrub in deciduous forests located in southwestern Ohio, USA from 2011 to 2017. Several leaf-litter ant community responses and litter biomass were measured in five paired deer access and exclosure plots, each with a split-plot removal of Amur honeysuckle (Lonicera maackii). Ant abundance and species richness increased with time in deer exclosures, but not in deer access plots. Honeysuckle removal reduced abundance and richness of ants. There were additive effects of deer and honeysuckle on ant richness, and interactive effects of deer and honeysuckle on ant abundance. Deer exclusion reduced variation in ant composition relative to access plots. There was little evidence that treatments directly influenced species diversity of ants. However, all ant measures were positively related to litter biomass, which was greater in deer exclosures relative to access plots. Our results indicate strong indirect effects of herbivores and honeysuckle on litter-dwelling ants, mediated through changes in litter biomass and likely vegetation structure, which may alter ant-mediated ecosystem processes.

Understanding what bioindicators are actually indicating: Linking disturbance responses to ecological traits of dung beetles and ants

Abstract Biological responses to a disturbance can vary among taxa, which challenges the use of bioindicators for representing biodiversity responses more broadly. Linking ecological traits to disturbance response helps clarify what different bioindicator groups are actually indicating, providing a mechanistic basis for predicting the responses of other taxa. Dung beetles and ants are ecologically contrasting but widely used bioindicator taxa. Here we link variation in dung beetle assemblages to body size and dung-feeding behavior, and variation in ant communities to habitat preferences, foraging behaviour and competitive dynamics, to clarify what dung-beetles and ants are indicating in terms of biodiversity responses to pastoral land management in a Brazilian savanna landscape. Dung beetles and ants were sampled at 24 pastoral sites that varied in grass cover, tree density, pasture age, cattle density, and frequency of parasiticide use. Community metrics (abundance, richness, composition, functional group composition) of both dung beetles and ants varied markedly with pastoral land management, but this variation was not correlated, or only weakly, between taxa. For dung beetles, abundance, biomass and richness were all best predicted by frequency of parasiticide use, whereas species composition was best predicted by cattle density. Tree density was the most important variable for explaining ant abundance (both total and of several functional groups) and was also significantly related to ant species composition. Dung beetles and ants provided different indications of the impacts of pastoral management on biodiversity. However, by linking responses to ecological traits we were able to clarify what they were actually indicating. Leaf-cutter ants showed a similar response to dung beetles; collectively they are indicating an impact of parasiticide use on dung-feeders. The abundance of small-sized roller beetles was negatively related to grass cover; along with ants they are indicating the importance of vegetation structure. Such a linking of disturbance responses to ecological traits allows for more-robust predictions of likely responses of other faunal groups. We believe that such an approach provides a substantially improved foundation for the use of bioindicators in land management.

Drivers of ant composition, richness, and trophic guilds in Neotropical iron ore cavities

Subterranean habitats may be considered limiting for animal colonization, especially for ants, due to permanent darkness and mainly because of oligotrophic conditions. While not as deep as limestone caves, iron ore caves and other subterranean habitats may be more available for colonization because of their shallower depth. We use the richness and composition of ants to assess how differences in habitat structure affect the biodiversity and ecosystem function between cavities and surrounding epigean landscapes. We predicted that the distribution of ants would be different because of the variation in habitat structure and cavity conditions may act as a filter for colonization by ants. A high diversity of ants was found in the 20 sampled cavities (26 species), and most of them were grouped in the generalist trophic guilds. The distribution of ants occurred independently of the type of cavity to which they are associated (caves, impacted caves and mines). Significant differences were observed in ant richness between epigean and cavities habitats, with lower average richness in cavities. The physical attributes of the cavities did not influence richness, mainly because cavity use by ants can usually be explained by their opportunistic habits and generalist lifestyle. Ants can participate directly in the cavities assemblage, playing roles in species composition and trophic functionality, due to the lower use restriction.

Are north Australian floodplain ant communities comprised of a distinct fauna, or a subset of the broader savanna fauna? Implications for conservation

There is newly invigorated interest in intensifying agriculture in northern Australia, and research has identified up to 17 M ha of suitable soils, much of which are floodplains. Given that 88% of these best soils for agriculture occur outside the current protected area network, and floodplains are a minority habitat in northern Australia, developing northern Australia whilst maintaining its biodiversity will be a great challenge. Ants are a particularly prominent and diverse faunal group within northern Australia, but almost nothing is known of the floodplain fauna. We sampled 20 pairs of plots in floodplains and surrounding savannas in three locations in the high rainfall zone of the Northern Territory to investigate the ant faunal composition of the floodplains, to determine to what extent they are comprised of species unique to floodplains or just a subset of the broader savanna fauna. We collected 114 species from 29 genera. Eighteen species were found only in floodplain plots, but only three were definitively floodplain specialists and another four had a propensity for clay soils. For all locations combined, savanna plots contained approximately 1.7 times more species than floodplain plots. Multivariate analysis found that the two habitats supported distinct ant faunas and the three locations also had distinct faunas. Nine species in this study were new to science, suggesting that there are many other species yet to be discovered. The results indicate that floodplains have conservation value for ant biodiversity, as is the case for other components of the biota. Efforts to intensify agriculture on north Australian floodplains therefore need to have effective conservation considerations if we are to achieve ecologically sustainable development.