Padrões de organização em comunidades de formigas nos campos sulinos e ecossistemas associados

Entender a distribuição de espécies em ecossistemas naturais e os processos envolvidos com estes padrões tem sido um tema cada vez mais importante devido a rápida perda e transformação de habitats atualmente. Com isso, é possível evitar potenciais perdas de espécies, funções ecológicas ou até mesmo histórias evolutivas de comunidades frente a mudanças climáticas e no uso da terra. O objetivo geral desta tese foi avaliar os padrões de organização de comunidades de formigas em ecossistemas campestres e florestais ao longo de toda distribuição dos Campos Sulinos no Sul do Brasil. Para isso, utilizei diferentes escalas espaciais e abordagens baseadas em diversidade taxonômica, atributos funcionais e relações filogenéticas de espécies de formigas. Os resultados obtidos para cada capítulo indicam que: (1) campos e florestas localizados em áreas de ecótonos são igualmente diversos quanto a riqueza de espécies e linhagens evolutivas de formigas, porém com distinta composição taxonômica entre ambientes (escala local) e regiões fisiográficas (escala regional); além disso, enquanto a filtragem ambiental explica os padrões em escala local, processos espaciais estão relacionados à escala regional; (2) diversidade taxonômica, funcional e filogenética de formigas seguem um clássico padrão latitudinal no Sul do Brasil, mas a variação interespecífica de tamanho de corpo mostra um padrão contrário (espécies menores em maiores latitudes); além disso, enquanto o aumento de precipitação e produtividade explicam a variação taxonômica e funcional, a diminuição da temperatura é o principal driver da diversidade filogenética; por fim (3) uma redução na porcentagem de cobertura florestal e na biomassa de serapilheira acumulada em florestas ripárias reduzem a diversidade de formigas, potenciais funções ecológicas e histórias evolutivas, indicando a importância da conservação destes ecossistemas. Os resultados desta tese contribuem com padrões de distribuição de espécies e descreve potenciais drivers e processos envolvidos. Além disso, do ponto de vista das formigas, tanto campos quanto florestas em mosaicos e maiores coberturas de matas ripárias devem ser preservadas.Understanding the species distribution in natural ecosystems and the processes behind these patterns has been an increasingly important issue due to the rapid habitat loss and transformation nowadays. Thus, it is possible to avoid potential loss of species, ecological functions or even evolutionary histories of communities to climate and land use change. The aim of this thesis was to evaluate the assembly patterns of ant communities in forest and grassland ecosystems throughout South Brazilian Grasslands. For this, I used different spatial scales and approaches based on taxonomic diversity, functional traits and phylogenetic relationships of ant species. The results obtained for each chapter indicated that: (1) forest and grassland habitats in ecotones are equally diverse in ant species richness and evolutionary lineages, but with distinct taxonomic composition between habitats (local scale) and physiographic regions (regional scale); furthermore, while environmental filtering explains the local scale patterns, spatial processes are related to the regional scale; (2) ant taxonomic, functional and phylogenetic diversity follows a classical latitudinal pattern in southern Brazil, and the interspecific variation in body size show the opposite pattern (lower size at highest latitudes); moreover, while the increase precipitation and productivity explain the taxonomic and functional variation, the decrease in temperature is the main driver of phylogenetic diversity; finally, (3) loss of the percentage of forest cover and leaf-litter biomass accumulated in riparian forests result in loss of ant diversity, potential ecological functions, and evolutionary histories, highlighting the importance of the conservation of these ecosystems. The results of this thesis contribute to species distribution patterns and describe potential drivers and processes involved. In addition, from the ants' point of view, both grasslands and forests in ecotones and larger riparian forest cover should be preserved. Key words: Formicidae; natural grasslands; ecotones; riparian forests; Pampa biome; Atlantica Forest biome; fire; grazing; taxonomic diversity; functional diversity; phylogenetic diversity; environmental variables

Ground-Dwelling and Vegetation Ant Fauna in Southern Brazilian Grasslands

Non-forest ecosystems, as natural grasslands from Southern Brazil, are still neglected in conservation policies. Measuring their biodiversity is one of the main steps to generate management strategies for these habitats. This study aims to (i) describe grassland ant richness and composition in Rio Grande do Sul state, and (ii) compare ant communities sampled on the ground and in grassland vegetation, adding to our knowledge of habitat use patterns and vegetation associated species. Six sites were sampled, three belonging to the Pampa biome and three in highland region from the Atlantic Forest biome. Ant fauna was collected once per year in summer during four years in each site with pitfalls traps and sweeping nets. Overall, 29,812 ant individuals were sampled belonging to eight subfamilies, 30 genera e 106 species. The grasslands of Pampa accumulated 91 species and 45 exclusive species, while highland grasslands summed up 61 species and only 15 exclusive species. Species composition differs between biomes as well as between sampling methods. Ant communities sampled from vegetation represented a clear subset of the fauna sampled with pitfall traps, and indication analysis showed only two species associated with this stratum: Myrmelachista gallicola and Pseudomyrmex nr. flavidulus. This study highlights the importance of Southern Brazilian grasslands and the need for specific conservation strategies for the natural grasslands from each biome

Efeito do pastejo sobre as assembleias de formigas nos campos sulinos

A conservação da biodiversidade aliada ao uso sustentável dos ecossistemas é considerada um grande desafio. A atividade pastoril é um dos principais tipos de uso da terra e cobre cerca de 25% da superfície terrestre. No entanto, apenas recentemente é que a manutenção da biodiversidade dos ecossistemas surgiu como preocupação em função desta prática. Os Campos Sulinos são ambientes do sul do Brasil que abrigam uma ampla riqueza de espécies. As formigas desempenham papéis essenciais nestes ecossistemas campestres e são fortemente recomendadas para avaliar efeitos do manejo da terra. Desta forma, foi avaliado experimentalmente o efeito de diferentes tipos de manejo pastoril sobre as assembleias de formigas nos Campos Sulinos. As coletas foram realizadas em seis localidades do Rio Grande do Sul (RS), nos anos de 2011, 2012 e 2013. Foram utilizados dois métodos amostrais: armadilhas de solo (pitfall trap) e rede de varredura (sweep net). Em cada localidade, três tipos de tratamentos foram avaliados: (i) manejo pastoril convencional, (ii) manejo pastoril sustentável e (iii) exclusão de pastejo. Foram coletadas 96 espécies de formigas, pertencentes a 28 gêneros. Houve redução significativa na abundância, riqueza e diversidade de espécies de formigas com três anos de abandono de manejo. A composição de espécies não foi afetada pelos tratamentos, apenas pelas diferentes regiões. A estrutura da vegetação e variáveis do habitat foram modificados ao longo do tempo, respondendo aos diferentes tipos de manejo pastoril. Espécies vegetais classificadas como touceiras apresentaram correlações negativas com as formigas, enquanto espécies lenhosas e forbs foram positivamente correlacionadas com estes organismos. Estes resultados demonstram que a ausência de manejo pastoril em campos nativos do RS afeta negativamente as assembleias de formigas, e poderão auxiliar na elaboração de futuros planos de conservação dos Campos Sulinos

Local and regional drivers of ant communities in forest-grassland ecotones in South Brazil: A taxonomic and phylogenetic approach.

Understanding biological community distribution patterns and their drivers across different scales is one of the major goals of community ecology in a rapidly changing world. Considering natural forest-grassland ecotones distributed over the south Brazilian region we investigated how ant communities are assembled locally, i.e. considering different habitats, and regionally, i.e. considering different physiographic regions. We used taxonomic and phylogenetic approaches to investigate diversity patterns and search for environmental/spatial drivers at each scale. We sampled ants using honey and tuna baits in forest and grassland habitats, in ecotones distributed at nine sites in Rio Grande do Sul state, Brazil. Overall, we found 85 ant species belonging to 23 genera and six subfamilies. At the local scale, we found forests and grasslands as equivalent in ant species and evolutionary history diversities, but considerably different in terms of species composition. In forests, the soil surface air temperature predicts foraging ant diversity. In grasslands, while the height of herbaceous vegetation reduces ant diversity, treelet density from forest expansion processes clearly increases it. At a regional scale, we did not find models that sufficiently explained ant taxonomic and phylogenetic diversity based on regional environmental variables. The variance in species composition, but not in evolutionary histories, across physiographic regions is driven by space and historical processes. Our findings unveil important aspects of ant community ecology in natural transition systems, indicating environmental filtering as an important process structuring the communities at the local scale, but mostly spatial processes acting at the regional scale

Epigeic ants (Hymenoptera: Formicidae) in vineyards and grassland areas in the Campanha region, state of Rio Grande do Sul, Brazil

In order to characterize the epigeic myrmecofauna in fields and vineyards in the physiographic region of Campanha, located in the Pampa biome, state of Rio Grande do Sul, inventories were conducted on three farms. On each farm, samples were collected in three environments: the rows in the vineyards, the spaces between rows in the vineyards, and the adjacent areas, with vegetation similar to that which preceded the establishment of crops. In each environment, 20 points were sampled using pitfall traps. We collected 72 species distributed among 24 genera and seven subfamilies. The study provides the first inventory of the ant fauna in the region, contributing with new records for the state of Rio Grande do Sul and for Brazil. It is hoped that this inventory will stimulate further studies on the biodiversity of this biome that is still poorly known

PREFERÊNCIA DE CORTE DE <i>Acromyrmex crassispinus</i> (FOREL, 1909) E <i>Acromyrmex ambiguus</i> (EMERY, 1887) (HYMENOPTERA: FORMICIDAE) POR DIFERENTES ESPÉCIES DE EUCALIPTOS EM LABORATÓRIO

<p>A busca por novos métodos de manejo e controle de formigas-cortadeiras vem sendo enfoque de inúmeros estudos pelo país, impulsionada por aspectos econômicos e ambientais. O estabelecimento de espécies resistentes ou menos preferidas ao corte pode contribuir substancialmente neste sentido. Logo, o objetivo deste estudo foi avaliar a preferência de corte entre as espécies <em>Corymbia citriodora</em>, <em>Eucalyptus benthamii</em>, <em>Eucalyptus camaldulensis</em>, <em>Eucalyptus dunnii</em>, <em>Eucalyptus globulus</em> e <em>Eucalyptus urograndis</em> por <em>Acromyrmex ambiguus</em> e <em>Acromyrmex crassispinus </em>em laboratório. Para isso, folhas foram ofertadas, simultaneamente, para seis colônias de cada espécie em bioensaios com chance de escolha. No entanto, nos testes sem chance de escolha, apenas as espécies menos preferidas pelo teste anterior foram utilizadas. Para <em>Acromyrmex crassispinus</em>, as espécies <em>Eucalyptus camaldulensis</em> e <em>Eucalyptus urograndis</em> foram mais cortadas, enquanto que as espécies <em>Corymbia citriodora</em>, <em>Eucalyptus dunnii</em> e <em>Eucalyptus globulus</em> foram menos preferidas ao corte. <em>Acromyrmex ambiguus</em> apresentou padrão similar de preferência, adicionando-se <em>Eucalyptus benthamii</em> entre as mais preferidas e excluindo-se <em>Eucalyptus dunnii</em> das menos preferidas.</p

Traffic within the Cytochrome b6f Lipoprotein Complex: Gating of the Quinone Portal

The cytochrome bc complexes b(6)f and bc(1) catalyze proton-coupled quinol/quinone redox reactions to generate a transmembrane proton electrochemical gradient. Quinol oxidation on the electrochemically positive (p) interface of the complex occurs at the end of a narrow quinol/quinone entry/exit Q(p) portal, 11 Å long in bc complexes. Superoxide, which has multiple signaling functions, is a by-product of the p-side quinol oxidation. Although the transmembrane core and the chemistry of quinone redox reactions are conserved in bc complexes, the rate of superoxide generation is an order of magnitude greater in the b(6)f complex, implying that functionally significant differences in structure exist between the b(6)f and bc(1) complexes on the p-side. A unique structure feature of the b(6)f p-side quinol oxidation site is the presence of a single chlorophyll-a molecule whose function is unrelated to light harvesting. This study describes a cocrystal structure of the cytochrome b(6)f complex with the quinol analog stigmatellin, which partitions in the Q(p) portal of the bc(1) complex, but not effectively in b(6)f. It is inferred that the Q(p) portal is partially occluded in the b(6)f complex relative to bc(1). Based on a discrete molecular-dynamics analysis, occlusion of the Q(p) portal is attributed to the presence of the chlorophyll phytyl tail, which increases the quinone residence time within the Q(p) portal and is inferred to be a cause of enhanced superoxide production. This study attributes a novel (to our knowledge), structure-linked function to the otherwise enigmatic chlorophyll-a in the b(6)f complex, which may also be relevant to intracellular redox signaling

12,500+ and counting: biodiversity of the Brazilian Pampa

Knowledge on biodiversity is fundamental for conservation strategies. The Brazilian Pampa region, located in subtropical southern Brazil, is neglected in terms of conservation, and knowledge of its biodiversity is fragmented. We aim to answer the question: how many, and which, species occur in the Brazilian Pampa? In a collaborative effort, we built species lists for plants, animals, bacteria, and fungi that occur in the Brazilian Pampa. We included information on distribution patterns, main habitat types, and conservation status. Our study resulted in referenced lists totaling 12,503 species (12,854 taxa, when considering infraspecific taxonomic categories [or units]). Vascular plants amount to 3,642 species (including 165 Pteridophytes), while algae have 2,046 species (2,378 taxa) and bryophytes 316 species (318 taxa). Fungi (incl. lichenized fungi) contains 1,141 species (1,144 taxa). Animals total 5,358 species (5,372 taxa). Among the latter, vertebrates comprise 1,136 species, while invertebrates are represented by 4,222 species. Our data indicate that, according to current knowledge, the Pampa holds approximately 9% of the Brazilian biodiversity in an area of little more than 2% of Brazil’s total land. The proportion of species restricted to the Brazilian Pampa is low (with few groups as exceptions), as it is part of a larger grassland ecoregion and in a transitional climatic setting. Our study yielded considerably higher species numbers than previously known for many species groups; for some, it provides the first published compilation. Further efforts are needed to increase knowledge in the Pampa and other regions of Brazil. Considering the strategic importance of biodiversity and its conservation, appropriate government policies are needed to fund studies on biodiversity, create accessible and constantly updated biodiversity databases, and consider biodiversity in school curricula and other outreach activities

ATLANTIC ANTS: a data set of ants in Atlantic Forests of South America

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