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Search Results: 1 - 10 of 210978 matches for " Heraldo L. Vasconcelos "
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Subterranean Pitfall Traps: Is It Worth Including Them in Your Ant Sampling Protocol?
Renata Pacheco,Heraldo L. Vasconcelos
Psyche , 2012, DOI: 10.1155/2012/870794
Abstract: The use of subterranean traps is a relatively novel method to sample ants, and few studies have evaluated its performance relative to other methods. We collected ants in forests, savannas, and crops in central Brazil using subterranean pitfall traps and conventional pitfall traps placed on the soil surface. Sampling duration, soil depth, and sprinkling vegetal oil around traps all tended to affect the number of species found in subterranean traps. Sixteen percent of the species collected in subterranean traps were unique, and most of these had cryptobiotic morphology (i.e., were truly hypogaeic species). Surprisingly, however, subterranean and conventional traps were similarly efficient at capturing cryptobiotic species. Furthermore, subterranean traps captured far fewer species in total than conventional traps (75 versus 220 species), and this was true in all three habitats sampled. Sampling completeness increased very little using a combination of conventional and subterranean traps than using just conventional traps.
Evaluation of three methods for sampling ground-dwelling Ants in the Brazilian Cerrado
Lopes, Cauê T.;Vasconcelos, Heraldo L.;
Neotropical Entomology , 2008, DOI: 10.1590/S1519-566X2008000400007
Abstract: few studies have evaluated the efficiency of methods for sampling ants, especially in regions with highly variable vegetation physiognomies such as the cerrado region of central brazil. here we compared three methods to collect ground-dwelling ants: pitfall traps, sardine baits, and the winkler litter extractor. our aim was to determine which method would be most appropriate to characterize the ant assemblages inhabiting different vegetation types. more species were collected with pitfall traps and with the winkler extractor than with sardine baits. pitfall traps collected more species in the cerrado (savanna) physiognomies, particularly in those with a poor litter cover, whereas the winlker extractor was more efficient in the forest physiognomies, except the one subject to periodic inundations. there was a low similarity in species composition between forest and cerrado physiognomies, and this pattern was detected regardless of the method used to sampling ants. therefore, even the use of a single, relatively selective method of collection can be enough for studies comparing highly distinct habitats and/or conditions. however, if the purpose of the sampling is to produce a more thoroughly inventory of the ant fauna, we suggest the use of a combination of methods, particularly pitfall traps and the winkler extractor. therefore, the ants of the leaf-litter (all) sampling protocol appear to be an adequate protocol for sampling ants in the highly-threatened brazilian cerrado biome.
Comunidade de formigas que nidificam em pequenos galhos da serrapilheira em floresta da Amaz?nia Central, Brasil
Carvalho, Karine S.;Vasconcelos, Heraldo L.;
Revista Brasileira de Entomologia , 2002, DOI: 10.1590/S0085-56262002000200002
Abstract: community of ants that nest in dead twigs on the ground of central amazonian forest, brazil. a total area of 2,880 m2 in four forest sites, near manaus, brazil, was searched for ant colonies nesting in dead twigs on the ground. an amount of 3,706 twigs (0.5-5 cm in diameter) were gathered, of which only 623 (16.8%) had ants, which is equivalent to a density of 0.22 nests per m2. seventy species have been found. the predominant genera were pheidole (westwood), crematogaster (lund), and solenopsis (westwood). for most species, many of the nests found had only workers and brood, suggesting that colonies either use multiple twigs to nest or do not live exclusively in the twigs, using other types of substrate (e.g., leaf-litter, soil, fruit pods) to nest. most colonized twigs were hollow or partially hollow inside and relatively easy to break apart. there were significant differences among species with respect to the size (diameter) of twig used as nest. no correlation was found between the number of twigs available and the number colonized by ants, suggesting that ant populations were not limited by the amount of nesting sites (twigs). the three most common pheidole species had small colonies with less than 200 workers. colony size was not related to twig size (volume), for any of these three species.
Arthropod responses to the experimental isolation of Amazonian forest fragments
Heraldo L. Vasconcelos,Emilio M. Bruna
Zoologia (Curitiba) , 2012,
Abstract: Arthropods are the most diverse and abundant group of animals found in tropical lowland forests, and in light of ongoing global change phenomena, it is essential to better understand their responses to anthropogenic disturbances. Here we present a review of arthropod responses to forest deforestation and fragmentation based on studies conducted at the Biological Dynamics of Forest Fragments Project (BDFFP), located in central Amazonia. These studies involved a wide range of arthropod groups. All but one of the studies evaluated changes in total species number or species density in relation to fragment size, (i.e. area effects), and one-third also evaluated edge effects. Our review indicates that almost every arthropod group studied showed some kind of response to reduction in forest area, including altered abundances, species richness or composition in comparisons of different-sized fragments, fragmented and non-fragmented areas, or comparisons of forest edges and forest interiors. These responses tended to be idiosyncratic, with some groups showing predicted declines in abundance or diversity in the fragments while others show no response or even increases. However, some of the observed effects on arthropods, or on the ecological processes in which they are involved, were transient. The most likely explanation for this was the rapid development of secondary growth around fragments, which greatly increased the connectivity between fragments and the remaining forest. Although the BDFFP has provided many insights regarding the effects of forest fragmentation on arthropod assemblages, many diverse groups, such as canopy arthropods, have received scant attention. For those that have been studied, much remains to be learned regarding the long-term dynamics of these assemblages and how landscape context influences local biodiversity. The BDFFP remains an exceptional site in which to investigate how the ecological interactions in which arthropods are engaged are altered in fragmented landscapes.
Resilient Networks of Ant-Plant Mutualists in Amazonian Forest Fragments
Heather A. Passmore, Emilio M. Bruna, Sylvia M. Heredia, Heraldo L. Vasconcelos
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040803
Abstract: Background The organization of networks of interacting species, such as plants and animals engaged in mutualisms, strongly influences the ecology and evolution of partner communities. Habitat fragmentation is a globally pervasive form of spatial heterogeneity that could profoundly impact the structure of mutualist networks. This is particularly true for biodiversity-rich tropical ecosystems, where the majority of plant species depend on mutualisms with animals and it is thought that changes in the structure of mutualist networks could lead to cascades of extinctions. Methodology/Principal Findings We evaluated effects of fragmentation on mutualistic networks by calculating metrics of network structure for ant-plant networks in continuous Amazonian forests with those in forest fragments. We hypothesized that networks in fragments would have fewer species and higher connectance, but equal nestedness and resilience compared to forest networks. Only one of the nine metrics we compared differed between continuous forest and forest fragments, indicating that networks were resistant to the biotic and abiotic changes that accompany fragmentation. This is partially the result of the loss of only specialist species with one connection that were lost in forest fragments. Conclusions/Significance We found that the networks of ant-plant mutualists in twenty-five year old fragments are similar to those in continuous forest, suggesting these interactions are resistant to the detrimental changes associated with habitat fragmentation, at least in landscapes that are a mosaic of fragments, regenerating forests, and pastures. However, ant-plant mutualistic networks may have several properties that may promote their persistence in fragmented landscapes. Proactive identification of key mutualist partners may be necessary to focus conservation efforts on the interactions that insure the integrity of network structure and the ecosystems services networks provide.
Asymmetric Dispersal and Colonization Success of Amazonian Plant-Ants Queens
Emilio M. Bruna, Thiago J. Izzo, Brian D. Inouye, Maria Uriarte, Heraldo L. Vasconcelos
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0022937
Abstract: Background The dispersal ability of queens is central to understanding ant life-history evolution, and plays a fundamental role in ant population and community dynamics, the maintenance of genetic diversity, and the spread of invasive ants. In tropical ecosystems, species from over 40 genera of ants establish colonies in the stems, hollow thorns, or leaf pouches of specialized plants. However, little is known about the relative dispersal ability of queens competing for access to the same host plants. Methodology/Principal Findings We used empirical data and inverse modeling—a technique developed by plant ecologists to model seed dispersal—to quantify and compare the dispersal kernels of queens from three Amazonian ant species that compete for access to host-plants. We found that the modal colonization distance of queens varied 8-fold, with the generalist ant species (Crematogaster laevis) having a greater modal distance than two specialists (Pheidole minutula, Azteca sp.) that use the same host-plants. However, our results also suggest that queens of Azteca sp. have maximal distances that are four-sixteen times greater than those of its competitors. Conclusions/Significance We found large differences between ant species in both the modal and maximal distance ant queens disperse to find vacant seedlings used to found new colonies. These differences could result from interspecific differences in queen body size, and hence wing musculature, or because queens differ in their ability to identify potential host plants while in flight. Our results provide support for one of the necessary conditions underlying several of the hypothesized mechanisms promoting coexistence in tropical plant-ants. They also suggest that for some ant species limited dispersal capability could pose a significant barrier to the rescue of populations in isolated forest fragments. Finally, we demonstrate that inverse models parameterized with field data are an excellent means of quantifying the dispersal of ant queens.
Estratifica??o vertical de formigas em cerrado strictu sensu no Parque Estadual da Serra de Caldas Novas, Goiás, Brasil
Campos, Ricardo I.;Lopes, Cauê T.;Magalh?es, Wagner C. S.;Vasconcelos, Heraldo L.;
Iheringia. Série Zoologia , 2008, DOI: 10.1590/S0073-47212008000300004
Abstract: formicidae is an abundant group in the soil and is also well distributed in all vegetation strata, representing a good model for studies on vertical stratification of the fauna. the aim of this study was to verify a possible stratification of ant assemblages inhabiting the soil, the lower and the higher vegetation strata. data was collected in the serra de caldas novas state park, in an area of cerrado strictu sensu. ant collection was performed using pitfall traps. a total of 11 traps were placed in the soil, 17 in the lower vegetation stratum (dominated by shrubs and small trees) and 23 in the higher vegetation stratum (dominated by taller, mature trees). forty-nine species of ants from 15 genera and five subfamilies were collected. accumulation curves indicated that there is 37.5% more species in the soil than in mature trees and 35% more species in mature trees than in shrubs/young trees. there was not a clear vertical stratification between the soil and the two vegetation strata. therefore, the species present in the vegetation tended to represent a nested subset of those found in the soil. even without a clear vertical stratification, the diversity of ants in the cerrado vegetation is high, and part of this diversity appears to be explained by the fact that some species are specialized in nesting and/or foraging in the soil, while others in the vegetation.
Patterns of diversity and abundance of fungus-growing ants (Formicidae: Attini) in areas of the Brazilian Cerrado
Vasconcelos, Heraldo L.;Araújo, Bruna B.;Mayhé-Nunes, Antonio J.;
Revista Brasileira de Zoologia , 2008, DOI: 10.1590/S0101-81752008000300009
Abstract: fungus-growing ants (tribe attini) are characteristic elements of the new world fauna. however, there is little information on the patterns of diversity, abundance, and distribution of attine species in their native ecosystems, especially for the so-called "lower" genera of the tribe. a survey of attine ant nests (excluding atta fabricus, 1804 and acromyrmex mayr, 1865) was conducted in a variety of savanna and forest habitats of the cerrado biome near uberlandia, brazil. in total, 314 nests from 21 species of nine genera were found. trachymyrmex forel, 1893 was the most diverse genus with 10 species. eighteen species were found in the savannas, including mycetagroicus cerradensis brand?o & mayhé-nunes, 2001, a species from a recently-described genus of attini, whereas in the forests only 12 species were found. forest and savannas support relatively distinct faunas, each with a number of unique species; the species present in the forest habitats did not represent a nested subset of the species found in the savannas. furthermore, although many species were common to both types of vegetation, their abundances were quite different. the density of attine nests is relatively high at some sites, exceeding an estimated 4,000 nests per hectare. in this sense, attine ants can be regarded as prevalent invertebrate taxa in the brazilian cerrado.
First record of the ant genus Probolomyrmex (Hymenoptera: Formicidae: Ponerini: Platythyreini) in Brazil
Jacques Hubert,Charles Delabie,Heraldo L. Vasconcelos,José M. S. Vilhena
Revista de Biología Tropical , 2001,
Effect of mutualist partner identity on plant demography
Emilio M Bruna,Thiago J Izzo,Brian D Inouye,Heraldo L Vasconcelos
PeerJ , 2015, DOI: 10.7287/peerj.preprints.368v2
Abstract: Mutualisms play a central role in the origin and maintenance of biodiversity. Because many mutualisms have strong demographic effects, interspecific variation in partner quality could have important consequences for population dynamics. Nevertheless, few studies have quantified how a mutualist partner influences population growth rates, and still fewer have compared the demographic impacts of multiple partner species. We used integral projection models parameterized with three years of census data to compare the demographic effects of two ant species – Crematogaster laevis and Pheidole minutula – on populations of the Amazonian ant-plant Maieta guianensis. Estimated population growth rates were positive (i.e., λ>1) for all ant-plant combinations. However, populations with only Pheidole minutula had the highest asymptotic growth rate (λ=1.23), followed by those colonized by Crematogaster laevis (λ=1.16), and in which the partner ant alternated between C. laevis and P. minutula at least once during our study (λ=1.15). Our results indicate that the short-term superiority of a mutualist partner – in this system P. minutula is a better defender of plants against herbivores than C. laevis – can have long-term demographic consequences. Furthermore, the demographic effects of switching among alternative partners appear to be context-dependent, with no benefits to plants hosting C. laevis but a major cost of switching to plants hosting P. minutula. Our results underscore the importance of expanding the study of mutualisms beyond the study of pair-wise interactions to consider the demographic costs and benefits of interacting with different, and multiple, potential partners.
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