Distribution of epigeic and hypogeic ants (Hymenoptera: Formicidae) in ombrophilous forests in the Brazilian Amazon

In the Amazon basin, ants are often associated with environmental or edaphic factors. However, these associations may vary between the epigeic and hypogeic strata. Here, we investigated differences in richness and composition of epigeic and hypogeic ant assemblages along an environmental gradient in the Brazilian Amazon. The four studied sites cover different topographic and soil characteristics. We sampled 25 plots of 250 m2 using 10 samples of epigeic pitfalls and 10 samples of hypogeic pitfalls installed at two depths (10 and 30 cm). The pitfalls remained in the fi eld for 48 hours. In the same plots, soil clay content and terrain altitude were also measured. We collected 219 species or morphospecies, of which 14 were exclusively hypogeics. We found higher local richness in the epigeic compared to hypogeic assemblages. We also found an interaction between clay content and strata for ant species composition. Overall, the species turnover was related to clay content, but the eff ect depended on the strata, with hypogeic fauna being more heterogeneous, compared with epigeic fauna. Despite the relationship between clay content and ant´s assemblage’s composition, we did not find strong environment predictors for both strata, which suggests that other factors may structure ant assemblages in these sites. This reinforces the need for studies to defi ne which environmental gradiente determines the distribution of Amazonian epigeic and hypogeic ants

Occurrence of triatomines (Hemiptera: Reduviidae) in domestic and natural environments in novo remanso, itacoatiara, amazonas, Brazil

Introduction: The present study reports the presence of triatomines in natural, peridomestic, and intradomicile environments in Itacoatiara municipality, state of Amazonas, a non-endemic region for Chagas disease. Methods: Active search was performed inside tree trunks, and palm trees, residences, and peridomiciles localized near the forest area. Results: Twenty adults and ten triatomines nymphs were collected, fifteen of which were from natural forests, thirteen from intradomiciles, and two from peridomicile areas. Conclusions: The new records of adults and nymphs of triatomines in the intra-and peridomiciles suggest the adoption of prophylactic measures for vector surveillance in the study area. © 2019, Sociedade Brasileira de Medicina Tropical. All rights reserved

Distribuição de espécies de formigas ao longo de um gradiente topográfico em uma reserva florestal de terra firme na Amazônia Central

In Amazonia, topographical variations in soil and forest structure within "terra-firme" ecosystems are important factors correlated with terrestrial invertebrates' distribution. The objective of this work was to assess the effects of soil clay content and slope on ant species distribution over a 25 km2 grid covering the natural topographic continuum. Using three complementary sampling methods (sardine baits, pitfall traps and litter samples extracted in Winkler sacks), 300 subsamples of each method were taken in 30 plots distributed over a wet tropical forest in the Ducke Reserve (Manaus, AM, Brazil). An amount of 26,814 individuals from 11 subfamilies, 54 genera, 85 species and 152 morphospecies was recorded (Pheidole represented 37% of all morphospecies). The genus Eurhopalothrix was registered for the first time for the reserve. Species number was not correlated with slope or clay content, except for the species sampled from litter. However, the Principal Coordinate Analysis indicated that the main pattern of species composition from pitfall and litter samples was related to clay content. Almost half of the species were found only in valleys or only on plateaus, which suggests that most of them are habitat specialists. In Central Amazonia, soil texture is usually correlated with vegetation structure and moisture content, creating different microhabitats, which probably account for the observed differences in ant community structure.Na Amazônia, variações topográficas em ecossistemas de terra-firme são variáveis comuns que afetam a distribuição de invertebrados terrestres. O objetivo deste trabalho foi avaliar os efeitos do conteúdo de argila no solo e da inclinação do terreno na distribuição de espécies de formigas em uma área de 25 km2 que cobre a variação topográfica natural. Usando três métodos de coleta complementares (iscas de sardinha, armadilhas de fosso e amostras de serapilheira extraídas de sacos de Winkler), foram coletadas 300 subamostras de cada método em 30 parcelas distribuídas em uma floresta tropical úmida na Reserva Ducke (Manaus, AM). Foram registrados 26.814 indivíduos em 11 subfamílias, 54 gêneros, 85 espécies e 152 morfoespécies (Pheidole representou 37% das morfoespécies). O gênero Eurhopalothrix foi registrado pela primeira vez nesta reserva. O número de espécies não foi correlacionado com a inclinação do terreno ou o conteúdo de argila, exceto para espécies na serapilheira. No entanto, a Análise das Coordenadas Principais indicou que a composição de espécies das armadilhas e da serapilheira esteve correlacionada com o conteúdo de argila. Aproximadamente metade das espécies foi encontrada somente nos baixios ou nos platôs, sugerindo que a maioria é especialista do habitat. Na Amazônia Central, a textura do solo está geralmente correlacionada com a estrutura da vegetação e o teor de umidade, criando micro-habitats heterogêneos que provavelmente contribuíram para as diferenças observadas na estrutura da comunidade de formigas

Edge effects on ant diversity and functional composition in a forest fragment in the Central Amazon

The process of human-induced forest fragmentation increases the degree of isolation and causes biodiversity loss. Abrupt changes occur mainly near the edge of the fragment, where the average temperature is relatively higher and the humidity is lower. However, some natural environmental characteristics, such as higher air moisture in riparian areas, may buffer or minimize the edge effects. Here, we studied how the edge effect may affect ant species diversity and functional composition on valleys dissected by small streams (mesic areas). We categorized ant assemblages into the functional groups based on foraging, nesting habits, natural history information, and phylogeny. Ants were sampled using pitfalls and the Winkler extractor in ten riparian plots in a fragment of the Central Amazon. We individually fit the ant species richness, occurrence, and composition against two edge measures: forest edge distance and road-building distance. We recorded 99 species/morphospecies. Forest edge distance and road-building distance did not influence the occurrence and number of ant species per plot but were related to ant species composition. Moreover, there was not a clear pattern between functional groups distribution, except by leaf-cutters and generalist omnivorous species. Our results suggest a limited effect of forest edge distance and road-building distance on ant diversit

Evolutionary history of the little fire ant Wasmannia auropunctata before global invasion: Inferring dispersal patterns, niche requirements and past and present distribution within its native range

The evolutionary history of invasive species within their native range may involve key processes that allow them to colonize new habitats. Therefore, phylogeographic studies of invasive species within their native ranges are useful to understand invasion biology in an evolutionary context. Here we integrated classical and Bayesian phylogeographic methods using mitochondrial and nuclear DNA markers with a palaeodistribution modelling approach, to infer the phylogeographic history of the invasive ant Wasmannia auropunctata across its native distribution in South America. We discuss our results in the context of the recent establishment of this mostly tropical species in the Mediterranean region. Our Bayesian phylogeographic analysis suggests that the common ancestor of the two main clades of W. auropunctata occurred in central Brazil during the Pliocene. Clade A would have differentiated northward and clade B southward, followed by a secondary contact beginning about 380 000 years ago in central South America. There were differences in the most suitable habitats among clades when considering three distinct climatic periods, suggesting that genetic differentiation was accompanied by changes in niche requirements, clade A being a tropical lineage and clade B a subtropical and temperate lineage. Only clade B reached more southern latitudes, with a colder climate than that of northern South America. This is concordant with the adaptation of this originally tropical ant species to temperate climates prior to its successful establishment in the Mediterranean region. This study highlights the usefulness of exploring the evolutionary history of invasive species within their native ranges to better understand biological invasions. © 2016 European Society for Evolutionary Biology

A test of the Geographic Mosaic Theory of Coevolution: investigating widespread species of Amazonian Protium (Burseraceae) trees, their chemical defenses, and their associated herbivore faunas

IntroductionPlants and their insect herbivores represent a large fraction of the species in Amazonian forests and are often directly implicated in the origin and maintenance of biodiversity at local and regional scales. How these interactions may change over geographic distance is unknown because very few studies have investigated the herbivore fauna and defense chemicals of any host plant species at multiple sites in tropical forests. One hypothesis, the Geographic Mosaic Theory of Coevolution, predicts that if herbivore assemblages turn over in different parts of a plant’s range, then plant defense chemicals should also change, reflecting local selection pressures.MethodsWe tested this theory by studying 12 species of Protium (Burseraceae) trees that occur in both Iquitos, Peru, and Manaus, Brazil, in rainforests separated by 1500 km. We surveyed all insects observed directly feeding on the plants in both locations for 48 weeks in Manaus and 64 weeks in Iquitos. We analyzed the secondary metabolites in the leaves of all species in both locations using GC/MS and HPLC.Results and DiscussionAlthough in both locations we found that Protium herbivores were dominated by insects from the orders Hemiptera, Coleoptera and Lepidoptera, we found almost complete turnover in the herbivore species composition in the two sites, and each host plant species had a different assemblage of herbivores in each location. Comparing the phylogenetic beta-diversity, we found low similarity in herbivore phylogenetic relatedness between host plant species in the two locations. However, the secondary metabolites found within a Protium species were similar across the two locations. We found no strong evidence that individuals from a host plant species in Iquitos or Manaus expressed locally-adapted defense chemicals, as individuals from geographic locations did not form clusters when looking at patterns of chemical similarity. These results are not consistent with the Geographic Mosaic Theory of Coevolution. The most intriguing pattern we found was a strong correlation between the diversity of herbivores per host plant species in both locations. We also found that plants with high chemical richness had lower numbers of herbivore species and numbers of total herbivores in both locations. We conclude that high chemical diversity is the most effective strategy for Protium trees to reduce insect herbivore attacks. We speculate that each secondary metabolite is effective at repelling only a few insect herbivores, and that different chemicals are likely effective in different parts of a plants’ geographic range. Future studies should investigate additional locations and additional natural enemies (i.e., fungal pathogens) to test the hypothesis that chemical diversity reduces attack from natural enemies and may explain the ecological and evolutionary success of rainforest trees over time and space

Climate mediates the effects of disturbance on ant assemblage structure

Many studies have focused on the impacts of climate change on biological assemblages, yet little is known about howclimate interacts with other major anthropogenic influences on biodiversity, such as habitat disturbance. Using a unique global database of 1128 local ant assemblages, we examined whether climate mediates the effects of habitat disturbance on assemblage structure at a global scale. Species richness and evenness were associated positively with temperature, and negatively with disturbance. However, the interaction among temperature, precipitation and disturbance shaped species richness and evenness. The effectwas manifested through a failure of species richness to increase substantially with temperature in transformed habitats at low precipitation. At low precipitation levels, evenness increased with temperature in undisturbed sites, peaked at medium temperatures in disturbed sites and remained low in transformed sites. In warmer climates with lower rainfall, the effects of increasing disturbance on species richness and evenness were akin to decreases in temperature of up to 98C. Anthropogenic disturbance and ongoing climate change may interact in complicated ways to shape the structure of assemblages, with hot, arid environments likely to be at greatest risk. © 2015 The Author(s) Published by the Royal Society. All rights reserved

Densidade de Iscas e variáveis ambientais influenciando a dominância nas comunidades de formigas em Florestas de Terra Firme, Amazônia Central, Manaus (AM)

Ants are present in most ecosystems and have been widely used to answer ecological questions in many different environments. This is because ant communities and populations are species rich and widely distributed. Dominance is a concept strongly related with richness, diversity, and relative abundance of species. The quality of the available resources directly affects the diversity patterns and consequently the dominance in ecological communities. In this work I evaluate the effects of resource gradients on dominance patterns (numerical and behavioral) and community richness in ant faunas from upland tropical rainforests ( terra firme ) nearby Manaus, Central Amazon. The influence of the volume, litter patchiness, soil moisture, and temperature upon these patterns was also investigated. The sampling consisted of 28 transects (100 m each) with bait density varying from 1 to 4 baits at each 10 m, and 27 transects (200 m each) with bait density varying from 0,5 to 2 baits each 20 m. Resource density have negative influence over behavioral dominance on longer transects (200 m), while in 100 m transects this effect was not found, probably due to environmental saturation with offered resources. The sampled numerical dominance and total richness were not affected by resource density. However, in transects with more bait density, a larger proportion of subdominant species were sampled. Environmental variables were sampled along 10 m intervals in smaller transects, and along 20 m intervals in longer transects. Because of the higher sampling detail, models of environmental variables generated by multiple regression analyses were only significant in the smaller transects. Behavioral and numerical dominance relationships were better explained by variables like litter volume and patchiness. In places with higher litter volume and patchiness, less baits were dominated (numerical and behaviorally). Soil moisture and temperature did not have significant influence on ant dominance patterns.Dominância é um conceito intrinsecamente ligado a riqueza, diversidade e abundância relativa de espécies. A quantidade de recursos disponíveis, ou produtividade, afeta diretamente a diversidade e conseqüentemente a dominância de uma comunidade. Neste trabalho examinei o efeito de gradientes de recursos, sobre os padrões de dominância (comportamental e numérica) e riqueza em comunidades de formigas de florestas de terra firme ao redor de Manaus, Amazônia Central. Também foram investigados como o volume e particulação do folhiço, umidade e temperatura do solo influenciam esses padrões. Foram criados dois gradientes de recursos: 28 transectos de 100 m com densidade de iscas variando entre 1 a 4 iscas a cada 10 m, e 27 transectos de 200 m com densidade de iscas entre 0,5 a 2 iscas a cada 10 m. Os tamanhos foram escolhidos por serem utilizados na maioria dos estudos de formigas. As variáveis ambientais foram amostradas em 10 pontos por transecto. Nos transectos menores, os pontos de coleta ficaram 10 m entre si, e nos transectos maiores, 20 m entre si. A dominância numérica e a riqueza total coletada por transecto não foram influenciadas pela variação na densidade de recursos. Porém em transectos com maior densidade de iscas, tanto de 100 m quanto de 200 m, proporcionalmente mais espécies de comportamento subdominante foram coletadas. A densidade de recursos teve uma influência negativa sobre a dominância comportamental, medida aqui pela proporção de iscas dominadas por transecto, somente nos transectos de 200 m. Já nos transectos de 100 m não houve efeito. A maior densidade de recursos, facilitou a dominação de mais iscas pela mesma colônia, e mais espécies dominantes e relativamente raras foram coletadas. Os modelos gerados por análises de regressão múltipla com as variáveis ambientais só foram significativos nos transectos menores, pelo levantamento mais detalhado do ambiente (pontos de amostragem a cada 10 m). Em locais com maior volume e particulação de folhiço, menos iscas foram dominadas (numericamente e comportamentalmente). A umidade e temperatura do solo não tiveram influência significativa sobre os padrões de dominância. Este trabalho mostra que a densidade dos recursos, e algumas variáveis ambientais atuam nas relações entre espécies em comunidades de formigas de solo

O papel de interações bióticas e fatores abióticos na estruturação de comunidades de formigas na Amazônia Central

One of the main goals in ecology is to determine which factors govern species cooccurence in local assemblages. This doctoral thesis documented the patterns of ant diversity across different forests and scales in Central Amazonia, and explored the possible mechanisms leading to these patterns. The role of antagonistic species interactions and environmental constraints on ant co-occurrence patterns were investigated through correlative studies based on field sampling at four sites. The sites cover a latitudinal gradient in Amazonian forests and encompass wide environmental heterogeneity, including areas of open and closed savannas, dense forests, and areas subject to different degrees soil water availability. The ant abundance, richness and composition also showed a marked variation between sites. Interference competition models tended to be more frequent in smaller sample units or in assemblages sampled with interactive methods, such as baits. The distance traveled between bait and nest entrance, including the dominant species, was relatively small. Both results suggests that competition from ecologically dominant species may reduce species richness in small areas especially when artificial baits are used, but appears to be less important than environmental constraints in determining ant species richness across scales of hectares and greater. The role of highly specialized parasites, which alter the behavior of their hosts to increase their own transmission, in structuring ant communities also appears to be small. There is a mismatch between infected and non-infected species distribution patterns suggesting that the number of host species suitable for behavioral manipulation is limited. These results, associated with small number of infected individuals around the colonies, probably limit the effect of these parasites regionally. The structures of ant assemblages studied were more strongly related to environmental restrictions than antagonistic interactions, such as inter-specific competition and parasitism. Regionally, fewer ant species were found in areas with lower average rainfall compared with areas with more water availability. Locally, the soil water availability, estimated by the water-table depth along one year, was also strong correlated with changes in ant assemblage structure. More ant species were found in areas with relative shallow water table. However, changes in number of species were mainly a result of an increase in generalist species associated with a decrease in the number of specialist predators and small hypogaeic generalist foragers. Although disturbance by the water-table may increase ant diversity at site scale, it reduces the ant assemblage functional diversity locally.Um dos principais objetivos da ecologia é determinar quais fatores determinam a coocorrência de espécies em assembleias locais. Esta tese de doutorado documentou os padrões de diversidade de formigas em diferentes florestas e escalas espaciais na Amazônia Central, e explorou os possíveis mecanismos ecológicos que resultam nesses padrões. O papel das interações antagônicas, como competição interespecífica e parasitismo, e restrições ambientais na organização de assembleias de formigas foi investigado através de estudos correlativos baseados em amostragem de campo em quatro locais. Os sítios estudados representam um gradiente latitudinal nas florestas amazônicas abrangendo ampla heterogeneidade ambiental, como áreas de savanas abertas e fechadas, florestas densas, e grande variação na disponibilidade de água do solo. A riqueza, abundância e composição de formigas também variou entre os sítios estudados. Modelos competitivos foram mais freqüentes em unidades amostrais menores ou nas assembleias de formigas amostradas com métodos interativos, como iscas artificiais. A distância percorrida entre as iscas e a entrada do ninho foi relativamente pequena, mesmo para as espécies ecologicamente dominantes. Ambos os resultados sugerem que a presença de espécies dominantes pode reduzir a riqueza de espécies de formigas em áreas pequenas, especialmente quando iscas artificiais são usadas, mas parece ser menos importante do que restrições ambientais na determinação da riqueza de espécies de formigas em escalas maiores. O papel de parasitas altamente especializados, que alteram o comportamento de seus hospedeiros para aumentar sua própria transmissão, na estruturação de comunidades de formigas também parece ser pequeno. Houve um desacoplamento entre os padrões de distribuição de espécies infectadas e não-infectadas, que sugere que o número de espécies hospedeiras adequadas para a manipulação comportamental é limitado. Esse resultado, associado ao pequeno número de indivíduos infectados ao redor das colônias, sugere que o efeito destes parasitas em escala regional também é limitado. A estrutura das assembleias de formigas estudadas foi mais fortemente relacionada com restrições ambientais do que interações antagônicas. Regionalmente, menos espécies de formigas foram encontradas em áreas com menor precipitação média em comparação com as áreas com maior disponibilidade de água. Localmente, a disponibilidade de água, estimada pela profundidade do lençol freático ao longo de um ano, também estiveram fortemente correlacionadas com alterações na estrutura das assembleias de formigas. Mais espécies de formigas foram encontradas em áreas com lençol freático relativamente raso. No entanto, as mudanças no número de espécies estão relacionadas com um aumento de espécies generalistas e a diminuição do número de predadores especialistas e espécies generalistas hipogéicas. Apesar da perturbação causada pelo lençol freático superficial aumentar a diversidade de formigas na escala do sítio, localmente ela reduz a diversidade funcional das assembleias de formigas