Diversity Of Ant Assemblages Research Articles

Functional composition of ant assemblages in habitat islands is driven by habitat factors and landscape composition

Fragmented natural habitats within human-transformed landscapes play a key role in preserving biodiversity. Ants as keystone species are essential elements of terrestrial ecosystems; thus, it is important to understand the factors influencing their presence. In a large-scale multi-site study, we surveyed ant assemblages using sweep netting and D-vac sampling on 158 ancient burial mounds preserving grassland habitats in agricultural landscapes in East-Hungary. We asked the following questions: (1) How do habitat factors and landscape composition affect species richness and functional diversity of ants? (2) Which ant traits are affected by habitat factors and landscape composition? Despite their small sizes, mounds as permanent and relatively undisturbed landscape elements could provide safe havens for diverse ant assemblages even in transformed agricultural landscapes. The complex habitat structure of wooded mounds supported high species and functional diversity of ant assemblages. Ant species on wooded mounds had small or medium-sized colonies, enabling the co-existence of more species. The effect of landscape composition on ant assemblages was mediated by habitat factors: steep slopes buffered the negative effect of the cropland matrix and enabled higher ant diversity.

β diversity among ant communities on fragmented habitat islands: the roles of species trait, phylogeny and abundance

Habitat loss and fragmentation reduce biodiversity and alter species composition in local communities. β diversity describes the variation in species composition between or among communities in fragmented landscapes and has two components: species turnover and nestedness. In this study, we assessed β diversity of ant assemblages on 24 island fragments in the Thousand Island Lake, China. We constructed a species‐level phylogenetic tree and measured five morphological traits of all ant species captured. We then assessed taxonomic (both incidence‐based and abundance‐weighted), functional and phylogenetic β diversity and partitioned β diversity into turnover and nestedness (as well as the contributions of particular species and particular islands). Finally, we examined the relationships between β diversity and a suite of geographical variables (i.e. difference in island area, difference in isolation and inter‐island distance) using Mantel tests. We found taxonomic and phylogenetic turnover components dominated overall β diversity whereas the functional turnover and nestedness components contributed equally to overall β diversity. Overall β diversity increased with increasing difference in isolation and inter‐island distance; however, only abundance‐weighted overall β diversity decreased with increasing difference in island size. Our results indicate that species that were abundant on large islands were also abundant on small islands. We conclude that the dispersal limitation of ants likely shapes the pattern of β diversity along isolation and inter‐island distance gradients. Additionally, functional redundancy of species (i.e. different species share similar functional roles) could also explain β diversity patterns among fragmented habitat islands. Our results highlight the necessity of incorporating both incidence‐based and abundance‐weighted community data when examining β diversity in fragmented landscapes. By partitioning β diversity into the contributions of particular species and particular fragments, our study implies that small patches can be valuable for maintaining biodiversity among ant communities.

Day-Night and Inter-Habitat Variations in Ant Assemblages in a Mosaic Agroforestry Landscape

Throughout the Mediterranean basin, the long-term interaction between human activities and natural processes has led to the formation of unique ecosystems whose biodiversity may be higher than that of the “original” systems. This is particularly true in the case of transformations of continuous stretches of closed forest into a complex mosaic of open and closed habitat over the course of centuries. In this study, we assessed the variation in diversity of ant assemblages in a typical patchy landscape, sampling ants in the three most important constituting habitats: olive plantation, harvested forest, and mature forest. In the study we used two different sampling methods—pitfall traps and observation at baits—which provided information on species presence at different temporal scales. The three habitats displayed different species assemblages, and considerable variation in species composition was observed at different times of the day, particularly in the harvested forest. Functional group analysis showed that the olive plantation, although the most artificial habitat, displayed the highest number of functional groups, suggesting a wider spectrum of available ecological niches for ant species within this habitat type. Overall, it was concluded that each of the three habitats contributes to enhance diversity at the landscape scale, which is greater than that expected from a more homogeneous habitat composition.

What is the influence of agroecological and conventional crops under ant assemblages?

The objective of the study was to compare the richness and diversity of ant assemblages in an agroecological system under peach orchard, conventional system under peach orchard cultivation and native vegetation in rural properties located in a Pampa Biome. The study was conducted in four samplings in 2017: 1st and 09th March (summer); 24th and 31st July (winter); and four samplings in 2018: 23rd and 30th January (summer); 31st July and 07th August (winter). Pitfall traps were used. The assemblages were characterized and compared using richness, number of occurrences of ants, Shannon diversity (H'), equitability, rarefaction analysis and Chao 1. The association of the species with the samples was evaluated by a Principal Component Analysis (PCA). The agroecological system had the highest number of occurrences, while the conventional orchard the lowest number. Richness and abundance were greatest during the summer. The conventional peach orchard obtained the lowest H' for both seasons when compared to the agroecological orchard and native vegetation. The PCA explained 77.40% of the occurrence of ants in the environments and in the seasons. The results found demonstrated that conservationist systems tend to harbor greater wealth and diversity of ant assemblages, as well as occurring in native áreas.

How estimated ant diversity is biased by the sampling method? A case study of Crete: a Mediterranean biodiversity hotspot

Defining biodiversity conservation goals requires representative and reliable data. However, data collected with the use of different methods can lead to divergent conclusions. Regardless of the high level of biodiversity of Mediterranean habitats, very little attention was paid in developing methods allowing rapid and scalable estimation of their richness. This study aims to recognize and explain the differences in performance of two methods: pitfall traps (PTM) and a complementary method based on hand collecting (HCM), in surveys of ants in the Mediterranean. We compared the results of applying both methods in three habitats in relation to α-, β-, and γ-diversity, and functional traits of species, i.e. Webber’s length (WL), nesting preferences, and evolutionary origin. Mean species number per HCM was significantly higher than per PTM sample. Spatial species turnover of HCM samples was higher than in PTM ones. However, assemblage dispersion did not differ. HCM detected a higher number of species and genera. WL differed significantly between HCM and PTM, and HCM recorded significantly more species in individual nesting guilds, regardless of considered habitat. HCM detected higher diversity of functional characteristic combinations of species. PTM detected fewer species with slightly larger body size and is useful in recognizing spatial species diversity patterns. HCM detected a higher number of species and produced more comprehensive results in identifying the functional diversity of ant assemblages. In conclusion, an integrated approach, described here as HCM, appears to be more suitable for heterogeneous Mediterranean habitats, especially when a survey aims at α-, β-, and γ-diversity assessments.

Diversity of ant assemblages (Hymenoptera: Formicidae) in an urban environment in Cameroon during and after colonization of the area by Wasmannia auropunctata

Invasive species disrupt the organization and functioning of many ant communities. Little is known about ant assemblages formerly in areas invaded by the little fire ant. In this study, we surveyed the same areas and compared the ant communities there when an invasive species first colonized the areas and 10 years later, using the same methodology (quadrat and baiting). A total of 83,299 worker ants from 17 species or morphospecies, in 4 subfamilies and 10 genera were recorded in the two periods sampled. Seven ant species were found to co-occur with W. auropunctata while 12 species were collected in the same area 10 years later, with no W. auropunctata recorded in any of the traps. In the absence of W. auropunctata, the number and diversity of ant species increased and the ant communities were dominated by the African big-headed ant, Pheidole megacephala. Our findings indicate that the disappearance of W. auropunctata is probably related to population increases in P. megacephala associated with dramatic changes in landscape. Further studies at other invaded locations should be carried out in order to reveal the generality of these patterns throughout this country.

Urban habitat complexity affects species richness but not environmental filtering of morphologically-diverse ants.

Habitat complexity is a major determinant of structure and diversity of ant assemblages. Following the size-grain hypothesis, smaller ant species are likely to be advantaged in more complex habitats compared to larger species. Habitat complexity can act as an environmental filter based on species size and morphological traits, therefore affecting the overall structure and diversity of ant assemblages. In natural and semi-natural ecosystems, habitat complexity is principally regulated by ecological successions or disturbance such as fire and grazing. Urban ecosystems provide an opportunity to test relationships between habitat, ant assemblage structure and ant traits using novel combinations of habitat complexity generated and sustained by human management. We sampled ant assemblages in low-complexity and high-complexity parks, and high-complexity woodland remnants, hypothesizing that (i) ant abundance and species richness would be higher in high-complexity urban habitats, (ii) ant assemblages would differ between low- and high-complexity habitats and (iii) ants living in high-complexity habitats would be smaller than those living in low-complexity habitats. Contrary to our hypothesis, ant species richness was higher in low-complexity habitats compared to high-complexity habitats. Overall, ant assemblages were significantly different among the habitat complexity types investigated, although ant size and morphology remained the same. Habitat complexity appears to affect the structure of ant assemblages in urban ecosystems as previously observed in natural and semi-natural ecosystems. However, the habitat complexity filter does not seem to be linked to ant morphological traits related to body size.

Effects of urbanization on the diversity of ant assemblages in tropical dry forests, Mexico

Urbanization has a direct effect on the landscape and its biodiversity, however urban centers has been ignored in most ecological studies. We study the diversity of ant communities in four remnants of tropical dry forest with different degrees of disturbance which are on the edge of the urban area in Queretaro city, Mexico. Samples were collected two times per month, from December 2004 to December 2005, in four strata: leaf litter, ground, scrub and arboreal. . A total of 25 species and 23 morphospecies were captured, belonging to 28 genera of 6 subfamilies: Dolichoderinae (3 species), Ecitoninae (5), Formicinae (12), Myrmicinae (24), Ponerinae (2) and Pseudomyrmicinae (2). Across the urban-disturbance gradient here studied the local diversity pattern could be explaining by the disturbance heterogeneity model. The most negative effect of urbanization was found for arboreal ants, while leaf litter communities were less susceptible to anthropogenic changes. In general, we found low rates of turnover, even in sites with high values of alpha diversity, evidencing the impoverishment of the ant community surrounding Queretaro city and the susceptibility of the community to extinction. The remnants were functionally very dissimilar and the effects of urbanization depend largely of the diet and life history of individual ant species. Moreover, it was found that the soil proprieties and vegetation structure influenced patterns of ant diversity along the urban-disturbance gradient. Despite the anthropogenic disturbance of the tropical dry forests surrounding the city of Queretaro, these forest remnants serve as a refuge for rare species and prove ecosystem functions. Ant biodiversity is also indicative of the state of ecosystem functions inside these remnants and likely of the biodiversity of other groups. Therefore, the conservation of these sites must be promoted to protect ant biodiversity and other taxonomic groups.

Alpha Diversity of the Myrmecofauna of the Natural Protected Area Metlac from Fortin, Veracruz, Mexico

Although the State of Veracruz is a megadiverse entity, it has the highest annual deforestation rates. Protected natural areas are considered strategic to preserve local biodiversity. In this paper, composition and alpha diversity of ant assemblages were analyzed in the natural protected area ‘Metlac’ near Fortin, Veracruz, Mexico. Sampling was conducted at four transects using baited pitfall traps and hand-collection. In total 3,204 ant workers belonging to 36 species, 21 genera, 12 tribes, and seven subfamilies were collected. The average alpha diversity was 16 species and no significant differences between recorded richness in each transect were found. Average sampling completeness was above 80%. Locally, Solenopsis geminata and Nylanderia steinheili dominate the epigeous and shrub strata due probably to their biological, behavioral and ecological plasticity that allows them to easily adapt to disturbed environments. This paper shows that for the small area sampled, the relict of tropical semi-evergreen forest is of great biological value despite heavy human intervention and the space-geographic context in which it is found.

Community structure and the habitat templet: ants in the tropical forest canopy and litter

The tropical forest canopy and litter differ in physical structure, resource availability, and abiotic conditions. We used standardized bait experiments in the canopy and litter of four neotropical tree species to explore how these differences shape the behavior, morphology, and diversity of ant assemblages. Ant activity (biomass at a bait after 32 min) was higher in the canopy, and higher on protein baits than carbohydrate baits. Aggressive bait defense occurred more frequently in the canopy (60%) than in the litter (32%), but was not associated with tree species or bait type in either habitat. The median size of workers of species in the canopy and litter was nearly identical, but body size distribution was unimodal in the canopy and bimodal in the litter. The colony size of the most aggressive species was an order of magnitude larger in the canopy. Species richness at a bait was relatively uniform across tree species and habitats. Litter and canopy shared no species, but overlap among tree species was three times higher in the litter assemblages. Litter assemblages showed less activity, less interference, less differentiation across the landscape, and different size distributions than canopy assemblages. The canopy and litter templets subsume a number of environmental gradients that combine to shape ant community structure.