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The global challenge of feeding two billion more people by 2050, using more sustainable agricultural practices whilst dealing with uncertainties associated with environmental change, requires a transformation of food systems. We present a new perspective for how advances in network science can provide novel ways to better understand, harness, and restore multiple ecological processes in agricultural environments. We describe: (i) a network-focused framework for managing agro-ecosystems that accounts for the multiple interactions between biodiversity and associated ecosystem services; (ii) guidance for incorporating socio-economic factors into ecological networks; and (iii) the potential to upscale network methods to inform efforts to build resilience, including global food-supply chains. In doing so we aim to facilitate the application of network science as a systems-based way to tackle the challenges of securing an equitable distribution of food.

The replacement of natural areas by urban areas promotes changes in the composition of tree communities, frequently favoring the occurrence of exotic species. This may have direct implications in the structure of pathogenic fungal communities which grow in these hosts. Here we examine: a) the structure of the interaction networks between urban tree species and their pathogenic wood-decay fungi, b) the composition of pathogenic fungi in native and exotic hosts. The interactions network shows a nested pattern where several species of pathogenic fungi establish multiple interactions with various tree species, both native and exotic; while others establish more specific interactions. Richness of pathogenic fungi was higher in exotic trees than in natives. Thirteen fungal species occurred exclusively in exotic hosts, one in natives and the remaining nine species shared both exotic and native hosts., El reemplazo de áreas naturales por zonas urbanizadas afecta la composición de las comunidades arbóreas, generalmente favoreciendo la ocurrencia de especies vegetales exóticas. Esto tendría implicancias directas en la estructuración de las comunidades de hongos patógenos que hospedan estas especies arbóreas. En este trabajo se propuso examinar: a) la estructura de la red de interacciones entre especies del arbolado urbano y los hongos patógenos degradadores de la madera, b) la composición de hongos patógenos en especies nativas y exóticas. Se observó que la red de interacciones mostró un patrón de anidamiento en donde varias especies de hongos patógenos establecen múltiples interacciones con diversas especies arbóreas, tanto nativas como exóticas, mientras que otras establecieron interacciones más específicas. Se observó mayor riqueza de hongos en árboles exóticos en comparación a sus pares nativos. Trece de las especies fúngicas se registraron exclusivamente en árboles exóticos, una exclusivamente en sustrato nativo y las nueve restantes compartieron tanto árboles exóticos como nativos.

La fragmentación de hábitats, mediada por los cambios en uso de la tierra, constituye una de las principales amenazas a la biodiversidad del planeta. En una comunidad, las especies se encuentran conectadas mediante relaciones tróficas que componen complejas redes de interacción. Debido a esto, los cambios en abundancia o pérdida de especies pueden tener efectos indirectos propagándose e incluso magnificándose a lo largo de las cadenas tróficas. Por lo tanto, entender la forma en que se pierden especies y el efecto de esta pérdida sobre la organización de la comunidad resultante son desafíos urgentes para los ecólogos. En este trabajo evaluamos la relación entre fragmentación de hábitat, extinciones y redes de interacción estudiando los cambios en la estructura de redes tróficas de plantas, insectos herbívoros y sus parasitoides en bosques del centro de Argentina. Encontramos que las redes son afectadas por una reducción en su tamaño, y aumentos de la intensidad relativa de interacción y la conectancia a medida que se reduce el área de bosque. Habitat fragmentation, mediated by land use change, is one of the major threats to biodiversity. In a community, species are connected by trophic relationships that comprise complex networks of interaction. Because of this, changes in abundance or loss of species may have indirect effects that spread and even magnify along the food chain. Therefore, understanding how species are lost and how these losses affect community organization are urgent challenges for ecologists. We evaluated the relationship between fragmentation and network structure by studying the changes in the structure of food webs of plant, insect herbivores and their parasitoids in forests of central Argentina. We found that the networks were affected by a reduction in size, and increased in relative interaction intensity and connectance as the forest area was reduced. Fil: Cagnolo, Luciano. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Investigaciones Entomológicas de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Valladares, Graciela Rosa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Investigaciones Entomologicas de Córdoba; Argentina

1. Ants establish mutualistic interactions involving a wide range of protective relationships (myrmecophily), in which they provide defence against enemies and partners provide food rewards and/or refuge. Although similar in the general outcome, myrmecophilic interactions differ in some characteristics such as quantity and quality of rewards offered by partners which may lead to different specialisation levels and, consequently, to different network properties. 2. The aim of this study was to identify structural patterns in myrmecophilic interaction networks, focusing on aspects related to specialisation: network modularity, nestedness and taxonomic relatedness of interaction ranges. To achieve this, a database of networks was compiled, including the following interactions: ants and domatia-bearing plants (myrmecophytes); ants and extrafloral nectary-bearing plants (EFNs); ants and floral nectary-bearing plants (FNs); ants and Lepidoptera caterpillars; and ants and Hemiptera. 3. Myrmecophilic networks differed in their topology, with ant–myrmecophyte and ant–Lepidoptera networks being similar in their structural properties. A continuum was found, ranging from highly modular networks and phylogenetically structured interaction ranges in ant–myrmecophyte followed by ant–Lepidoptera networks to low modularity and taxonomically unrelated interaction ranges in ant–Hemiptera, EFN and FN networks. 4. These results suggest that different network topologies may be found across communities of species with similar interaction types, but also, that similar network topologies can be achieved through different mechanisms such as those between ants and myrmecophytes or Lepidoptera larvae. This study contributes to a generalisation of myrmecophilic network patterns and a better understanding of the relationship between specialisation and network topology. Fil: Cagnolo, Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Tavella, Julia Rita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina

In the past decade, ecologists have increasingly applied complex network theory (1, 2) to ecological interactions, both in entire food webs (3) and in networks representing ecological interactions, especially those between plants and their animal pollinators or seed dispersers (4). How important are individual species to the maintenance of such ecological networks? On page 1489 of this issue, Stouffer et al. (5) analyze terrestrial, freshwater, and marine food webs to infer the contributions of individual species to network stability. In a related field study on page 1486 of this issue, Aizen et al. (6) explore plant and pollinator webs on a landscape scale. Using a different field study design, Pocock et al. (7) recently focused on a local community in which several webs of different kinds of interactions and organisms form a composite network. Fil: Lewinsohn, Thomas. Universidade Estadual de Campinas; Brasil Fil: Cagnolo, Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentina

The structure of mutualistic networks is likely to result from the simultaneous influence of neutrality and the constraints imposed by complementarity in species phenotypes, phenologies, spatial distributions, phylogenetic relationships, and sampling artifacts. We develop a conceptual and methodological framework to evaluate the relative contributions of these potential determinants. Applying this approach to the analysis of a plant–pollinator network, we show that information on relative abundance and phenology suffices to predict several aggregate network properties (connectance, nestedness, interaction evenness, and interaction asymmetry). However, such information falls short of predicting the detailed network structure (the frequency of pairwise interactions), leaving a large amount of variation unexplained. Taken together, our results suggest that both relative species abundance and complementarity in spatiotemporal distribution contribute substantially to generate observed network patters, but that this information is by no means sufficient to predict the occurrence and frequency of pairwise interactions. Future studies could use our methodological framework to evaluate the generality of our findings in a representative sample of study systems with contrasting ecological conditions. Fil: Vázquez, Diego Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina Fil: Chacoff, Natacha Paola. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina Fil: Cagnolo, Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina

Habitat fragmentation is the transformation of once-extensive landscapes into smaller, isolated remnants surrounded by new types of habitat. There is ample evidence of impoverished biodiversity as a consequence of habitat fragmentation, but its most profound effects may actually result from functional changes in ecological processes such as trophic interactions. We studied the trophic processes of herbivory and parasitism in insect-plant food webs composed of hundreds of species in a fragmented woodland landscape. We recorded all plant species, collected mined leaves, and reared leafminers and parasitoids from 19 woodland remnants. Herbivory and parasitism rates were then analyzed in relation to woodland size and edge or interior location. Herbivory by leaf-mining insects and their overall parasitism rates decreased as woodland remnants became smaller. For each remnant, the intensity of both processes differed between edge and interior. Our results provide novel evidence of the magnitude of habitat fragmentation effects, showing they can be so pervasive as to affect trophic processes of highly complex food webs and suggesting a response associated with trophic specialization of the involved organisms as much as with their trophic level. Fil: Valladares, Graciela Rosa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Salvo, Silvia Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Cagnolo, Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina

The effects of grazing disturbance on insect communities were examined at a montane grassland in Central Argentina, by comparing two grazed sites differing in cattle load (heavy and continuous or moderate and discontinuous) and two cattle exclusions differing in age (7 and 19 years). Two aspects of insect diversity (taxonomic and guild structure) and two levels of taxonomic resolution (family and species) were considered. Four monthly samples were taken with a suction sampler in two 1 m2 areas at each site. Collected specimens were counted, identified to family (all insects) or species (Coleoptera) level, and allocated to trophic guilds. Abundance, richness, diversity and biomass of the insect assemblages had minimum values in the most intensely grazed habitat, which also differed from the other sites in terms of insect families and Coleoptera species composition. It also showed a distinct guild structure, with fewer secondary consumers, and chewers replacing suckers as the most abundant herbivore group. According to these observations, intense grazing in montane grasslands in Central Argentina could result in taxonomic and guild changes in the associated insect communities, but such effects would not be noticeable with less intensive use. Moreover, using family taxonomic level could be as or even more appropriate than species level in order to characterize insect communities in the studied habitats under varying disturbance regimes. Fil: Cagnolo, Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Molina, Silvia Itatí. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Valladares, Graciela Rosa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina

Orientador: Thomas Michael Lewinsohn Texto em português e inglês Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia Resumo: Nesta tese propomos um desenvolvimento do conceito de especialização no uso de recursos, de forma a incluir aspectos pouco considerados, principalmente no contexto de interações: afinidades entre os tipos de recursos, sua disponibilidade e padrões de coocorrência. Por meio da incorporação de avanços recentes em estudos ecofilogenéticos e em modelos nulos, propomos novas métricas para a especialização de espécies e comunidades, e aplicamos esses avanços para responder a questões particulares. No primeiro capítulo, o arcabouço conceitual é apresentado de forma mais geral, e uma métrica para a especialização de espécies é proposta e exemplificada. O segundo capítulo, de natureza metodológica, estende essa métrica para comunidades e propõe uma partição da variação em especialização entre espécies e entre locais de forma hierarquizada. O terceiro capítulo investiga a capacidade destas ferramentas de evidenciar relações entre a especialização e a distribuição geográfica de espécies de insetos endófagos de capítulos de Asteraceae no Brasil. Por fim, o quarto capítulo utiliza o mesmo conjunto de dados para investigar o papel da diversidade filogenética de recursos na determinação da riqueza de insetos que os utilizam Abstract: In this thesis we propose a development of the resource specialization concept to include aspects usually not taken into account, especially for trophic interactions: affinities among resource types, their availabilities and cooccurrence patterns with consumers. By incorporating recent advances in ecophylogenetics and null modelling, we propose new metrics for the specialization of species and communities and apply these advances to address particular questions. In the first chapter the general conceptual framework is presented and a metric for the specialization of species is proposed and exemplified. The second chapter, mostly methodological, expands this metric for communities and proposes a hierarchical partitioning of the variation in specialization among species and locations. The third chapter tests this toolset in showing the relationship between specialization and geographic distribution ranges of endophagous insects feeding in Asteraceae flowerheads in Brazil. Finally, the fourth chapter uses the same dataset to investigate the role of phylogenetic diversity of resources in determining the richness of insect herbivores using them Doutorado Ecologia Doutor em Ecologia

Los ambientes marinos profundos incluyen una diversidad de ecosistemas que se encuentran en un rango entre 200 y 10.900 m de profundidad. Si bien constituyen el bioma más extenso de la Tierra, aún hoy permanecen escasamente estudiados. Las planicies abisales (3.000 - 6.000 m) y los taludes continentales (200 - 3.000 m) constituyen los ambientes marinos profundos de mayorextensión. En particular, el talud continental argentino (35°S - 55°S) es uno de los más extensos en el mundo. Las ascidias (Chordata, Tunicata) son componentes importantes de las comunidades bentónicas de ambientes profundos. No obstante, el conocimiento que se tiene de la ascidiofauna profunda es también acotado. En la presente tesis se identificaron ascidias provenientes de las primeras campañas exploratorias del talud continental argentino, alrededor de los 38°S, del BuqueOceanográfico A.R.A. "Puerto Deseado". También se identificaron ascidias de las planicies abisales antárticas provenientes de la expedición ANT XXII/3 (ANDEEP III), en el Mar de Weddell. Se incrementó el conocimiento sobre la diversidad y los rangos de distribución y profundidad de estos organismos. Por otra parte, se evaluó el patrón de zonación de los ensambles de ascidias enla zona del talud estudiada. Los resultados obtenidos sumando datos de estas campañas y registros de bibliografía revelaron la existencia de un patrón de zonación determinado por latopografía propia del lugar. Con el fin de evaluar los patrones de distribución de la ascidiofauna marina profunda se elaboró una lista de ascidias con registros