Ilhas florestais, redes de interação formiga-planta e a conservação de processos ecológicos

Ant-plant mutualism is an important feature of the Amazon biodiversity. Its coevolutionary trajectories which generated tight compartmented networks are nowadays threatened by habitat alteration. The recent Brazilian demand for energy is leading to the construction of a series of hydroelectric which causes habitat loss and fragmentation. Our goal is to test how dam fragmentation affects the structure of ant-plant mutualistic networks, in particular species density and richness, connectance, modularity, and nestedness. We compared the networks of continuous forest with those from islands and lake edges as well as how networks change among islands varying in area, isolation, shape, and neighborhood. We developed the study in the Biological Reserve of Uatumã in Central Amazon, which includes the continuous forest around the 3147 km 2 of the Balbina dam reservoir and more than 3500 islands. Ant-plant communities were surveyed along 600 x 5 m plots in 20 islands, 5 lake edges, and 6 forests sites. Plant and ant richness and density was lower in islands and lake edge in comparison with forest, increased with island area and decreased with isolation. Density of all myrmecophyte species decreased from forest to lake edge and island. Unoccupied plants percentage was three times higher on islands than on forest. Plant and ant community, as well as interactions on islands and lake edge were nested with forest. Forest network was highly compartmented, while island and lake edge networks lost species, interactions and compartments and won new opportunistic ant species. Connectance didn’t change among habitats and was not related to islands traits. Natural history, landscape traits, ecological processes decay, coextinction, and new interactions were discussed as the main factors involved on nested communities, networks changes, species loss and connectance constancy of our community. Coextinction and interaction loss by dam fragmentation can influence evolutionary processes with important implications for conservation.O mutualismo formiga-planta é uma característica importante da biodiversidade na Amazônia. Tal trajetória co-evolutiva gerou redes de interação fortemente compartimentadas, atualmente ameaçadas por alterações ambientais. A recente demanda brasileira por energia tem levado a construção de uma série de hidrelétricas que causam perda de habitat e fragmentação devido à inundação provocada pelo represamento dos rios. O objetivo deste trabalho é testar como a fragmentação e a perda de habitat afetam a estrutura de redes de mutualismo formiga-planta, especificamente riqueza e densidade de espécies, conectância, modularidade e aninhamento. Nós comparamos as redes da floresta contínua com aquelas das ilhas e da borda do lago, bem como a mudança das redes das ilhas em relação à área, isolamento, forma e vizinhança. O estudo foi desenvolvido na Reserva Biológica do Uatumã na Amazônia Central, que inclui a floresta contínua em torno dos 3127 km 2 do reservatório da hidrelétrica de Balbina e mais de 3500 ilhas. A comunidade formiga-mirmecófita foi investigada em plotes de 600 x 5 m em 20 ilhas, 5 áreas na borda do lago e 6 áreas na floresta contínua. A riqueza e a densidade de plantas e formigas foram menores nas ilhas e na borda do lago em relação à floresta, aumentou com a área e diminui com o isolamento das ilhas. A densidade de todas as espécies de plantas diminuiu da floresta para borda do lago e para as ilhas. A porcentagem de plantas desocupadas sem proteção de formigas foi três vezes maior nas ilhas em relação à floresta. As comunidades de plantas e de formigas, bem como as interações nas ilhas e na borda do lago são aninhadas com a comunidade da floresta. A rede de interação formiga-mirmecófita na floresta foi altamente compartimentada, enquanto que as redes das ilhas e da borda do lago perderam espécies, interações e compartimentos e ganharam novas espécies oportunistas de formigas. A conectância se manteve constante com a fragmentação da paisagem e não esteve relacionada a nenhuma característica das ilhas. História natural, características da paisagem, quebra de processos ecológicos, coextinção e novas interações foram discutidos como os principais fatores envolvidos no aninhamento das comunidades, mudanças nas redes, perda de espécies e manutenção da conectância. Coextinção e perda de interações por fragmentação por hidrelétricas podem influenciar processos evolutivos com importantes implicações para a conservação

The impact of the invasive alien plant, impatiens glandulifera, on pollen transfer networks

Biological invasions are a threat to the maintenance of ecological processes, including pollination. Plant-flower visitor networks are traditionally used as a surrogated for pollination at the community level, despite they do not represent the pollination process, which takes place at the stigma of plants where pollen grains are deposited. Here we investigated whether the invasion of the alien plant Impatiens glandulifera (Balsaminaceae) affects pollen transfer at the community level. We asked whether more alien pollen is deposited on the stigmas of plants on invaded sites, whether deposition is affected by stigma type (dry, semidry and wet) and whether the invasion of I. glandulifera changes the structure of the resulting pollen transfer networks. We sampled stigmas of plants on 10 sites invaded by I. glandulifera (hereafter, balsam) and 10 non-invaded control sites. All 20 networks had interactions with balsam pollen, although significantly more balsam pollen was found on plants with dry stigmas in invaded areas. Balsam pollen deposition was restricted to a small subset of plant species, which is surprising because pollinators are known to carry high loads of balsam pollen. Balsam invasion did not affect the loading of native pollen, nor did it affect pollen transfer network properties; networks were modular and poorly nested, both of which are likely to be related to the specificity of pollen transfer interactions. Our results indicate that pollination networks become more specialized when moving from the flower visitation to the level of pollen transfer networks. Therefore, caution is needed when inferring pollination from patterns of insect visitation or insect pollen loads as the relationship between these and pollen deposition is not straightforward

A plant–pollinator metanetwork along a habitat fragmentation gradient

To understand how plant–pollinator interactions respond to habitat fragmentation, we need novel approaches that can capture properties that emerge at broad scales, where multiple communities engage in metanetworks. Here we studied plant–pollinator interactions over 2 years on 29 calcareous grassland fragments selected along independent gradients of habitat size and surrounding landscape diversity of cover types. We associated network centrality of plant–pollinator interactions and grassland fragments with their ecological and landscape traits, respectively. Interactions involving habitat specialist plants and large-bodied pollinators were the most central, implying that species with these traits form the metanetwork core. Large fragments embedded in landscapes with high land cover diversity exhibited the highest centrality; however, small fragments harboured many unique interactions not found on larger fragments. Intensively managed landscapes have reached a point in which all remaining fragments matter, meaning that losing any further areas may vanish unique interactions with unknown consequences for ecosystem functioning

Cytogenetic characterization of Angelonia integerrima Sprengel, a native species with ornamental potential

Angelonia integerrima Sprengel is a native species of the state of Mato Grosso do Sul and the Southern region (Paraná, Santa Catarina and Rio Grande do Sul) of Brazil, with features such as an unusual appearance and color of the flowers, indicating an ornamental use. To optimize the use of this species and to fill in gaps regarding its cytogenetic characterization, this study determined the chromosome number, meiotic index and pollen viability of plant individuals of four A. integerrima populations. All plant individuals of the four populations had 2n = 20 chromosomes. Still, the meiotic index of most analyzed plant individuals exceeded 90%, while pollen viability of all plant individuals was higher than 80%. These data suggest considerable cytological stability of the analyzed A. integerrima plant individuals, which may favor the selection of future genotypes for commercial purposes or their use in conservation and breeding programs of the species

Emergent properties of species-habitat networks in an insular forest landscape

Deforestation and fragmentation are pervasive drivers of biodiversity loss, but how they scale up to entire landscapes remains poorly understood. Here, we apply species-habitat networks based on species co-occurrences to test the effects of insular fragmentation on multiple taxa-medium-large mammals, small nonvolant mammals, lizards, understory birds, frogs, dung beetles, orchid bees, and trees-across 22 forest islands and three continuous forest sites within a river-damming quasi-experimental landscape in Central Amazonia. Widespread, nonrandom local species extinctions were translated into highly nested networks of low connectance and modularity. Networks' robustness considering the sequential removal of large-to-small sites was generally low; between 5% (dung beetles) and 50% (orchid bees) of species persisted when retaining only <10 ha of islands. In turn, larger sites and body size were the main attributes structuring the networks. Our results raise the prospects that insular forest fragmentation results in simplified species-habitat networks, with distinct taxa persistence to habitat loss

Global and regional ecological boundaries explain abrupt spatial discontinuities in avian frugivory interactions

Species interactions can propagate disturbances across space via direct and indirect effects, potentially connecting species at a global scale. However, ecological and biogeographic boundaries may mitigate this spread by demarcating the limits of ecological networks. We tested whether large-scale ecological boundaries (ecoregions and biomes) and human disturbance gradients increase dissimilarity among plant-frugivore networks, while accounting for background spatial and elevational gradients and differences in network sampling. We assessed network dissimilarity patterns over a broad spatial scale, using 196 quantitative avian frugivory networks (encompassing 1496 plant and 1004 bird species) distributed across 67 ecoregions, 11 biomes, and 6 continents. We show that dissimilarities in species and interaction composition, but not network structure, are greater across ecoregion and biome boundaries and along different levels of human disturbance. Our findings indicate that biogeographic boundaries delineate the world’s biodiversity of interactions and likely contribute to mitigating the propagation of disturbances at large spatial scales.The authors acknowledge the following funding: University of Canterbury Doctoral Scholarship (L.P.M.); The Marsden Fund grant UOC1705 (J.M.T., L.P.M.); The São Paulo Research Foundation - FAPESP 2014/01986-0 (M.G., C.E.), 2015/15172-7 and 2016/18355-8 (C.E.), 2004/00810-3 and 2008/10154-7 (C.I.D., M.G., M.A.P.); Earthwatch Institute and Conservation International for financial support (C.I.D., M.G., M.A.P.); Carlos Chagas Filho Foundation for Supporting Research in the Rio de Janeiro State – FAPERJ grant E-26/200.610/2022 (C.E.); Brazilian Research Council grants 540481/01-7 and 304742/2019-8 (M.A.P.) and 300970/2015-3 (M.G.); Rufford Small Grants for Nature Conservation No. 22426–1 (J.C.M., I.M.), No. 9163-1 (G.B.J.) and No. 11042-1 (MCM); Universidade Estadual de Santa Cruz (Propp-UESC; No. 00220.1100.1644/10-2018) (J.C.M., I.M.); Fundação de Amparo à Pesquisa do Estado da Bahia - FAPESB (No. 0525/2016) (J.C.M., I.M.); European Research Council under the European Union’s Horizon 2020 research and innovation program (grant 787638) and The Swiss National Science Foundation (grant 173342), both awarded to C. Graham (D.M.D.); ARC SRIEAS grant SR200100005 Securing Antarctica’s Environmental Future (D.M.D.); German Science Foundation—Deutsche Forschungsgemeinschaft PAK 825/1 and FOR 2730 (K.B.G., E.L.N., M.Q., V.S., M.S.), FOR 1246 (K.B.G., M.S., M.G.R.V.) and HE2041/20-1 (F.S., M.S.); Portuguese Foundation for Science and Technology - FCT/MCTES contract CEECIND/00135/2017 and grant UID/BIA/04004/2020 (S.T.) and contract CEECIND/02064/2017 (L.P.S.); National Scientific and Technical Research Council, PIP 592 (P.G.B.); Instituto Venezolano de Investigaciones Científicas - Project 898 (V.S.D.)

Ecological network complexity scales with area

Larger geographical areas contain more species—an observation raised to a law in ecology. Less explored is whether biodiversity changes are accompanied by a modification of interaction networks. We use data from 32 spatial interaction networks from different ecosystems to analyse how network structure changes with area. We find that basic community structure descriptors (number of species, links and links per species) increase with area following a power law. Yet, the distribution of links per species varies little with area, indicating that the fundamental organization of interactions within networks is conserved. Our null model analyses suggest that the spatial scaling of network structure is determined by factors beyond species richness and the number of links. We demonstrate that biodiversity–area relationships can be extended from species counts to higher levels of network complexity. Therefore, the consequences of anthropogenic habitat destruction may extend from species loss to wider simplification of natural communities.This work was supported by the TULIP Laboratory of Excellence (ANR-10-LABX-41 and 394 ANR-11-IDEX-002-02) to J.M.M., by a Region Midi-Pyrenees project (CNRS 121090) to J.M.M., and by the FRAGCLIM Consolidator Grant (726176) to J.M.M. from the European Research Council under the European Union’s Horizon 2020 Research and Innovation Program. The study was also supported by Spanish MICINN projects CGL2009-12646, CSD2008-0040 and CGL2013-41856 to J.B. and A.R. C.E. was funded through the São Paulo Research Foundation (FAPESP 2015/15172-7). V.A.G.B. was funded by National Funds through FCT—Foundation for Science and Technology under the Project UIDB/05183/2020. W.T. received funding from the ERA-Net BiodivERsA—Belmont Forum, with the national funder Agence National pour la Recherche (FutureWeb: ANR-18-EBI4–0009 and BearConnect: ANR-16-EBI3-0003).Peer reviewe

Vulnerabilidade estrutural dos hospitais e cemitérios e crematórios da cidade de São Paulo à COVID-19

This is the first report by the COVID19 Observatory - Group: Contagion Networks analyzing mortality data from the city of São Paulo. In this report, we integrated mortality data for the city of São Paulo between 04/02/2020 and 04/28/2020, with information on the flow of victims between hospitals and cemeteries/crematoriums. We included in our analyzes both confirmed and suspected deaths from COVID-19. The main objectives of this report were: (1) to describe the structure of the flow of victims between locations and (2) to suggest changes in the current flow based on geographical distances in order to avoid a potential overload of the mortuary system. We suggest that the city of São Paulo should plan for a potential overload of the mortuary system (that is, the number of burials), based on the presented results. Thus, our results reinforce the need to adopt specific planning for the management of the extraordinary number of victims of this pandemic. Our predictions are based on the structural analysis of the COVID-19 victim flow network, which shows several hotspots with high vulnerability to system overload. These hotspots concentrate with either the greatest number of deaths (hospital) or of burials (cemetery or crematorium), and therefore have high potential to become overwhelmed by receiving many bodies due to the increase in victims of the pandemic. We recommend special attention to be given to localities on the east side of São Paulo, which has both the most vulnerable hospitals in the city, and also houses cemeteries and crematoriums that have a central role in the network and / or are vulnerable. Based on our optimization analysis, we suggest logistical changes in the current flow of bodies from hospitals to cemeteries/crematoriums so as not to overload the funeral system and minimize transportation costs. In this sense, our results are potentially useful for improving the operational planning of the Municipality of São Paulo, ratifying or rectifying actions underway at the municipal level.Este é o primeiro relatório do Observatório COVID19 - Grupo: Redes de Contágio analisando os dados de óbitos da cidade de São Paulo. Neste relatório, integramos os dados de óbitos da cidade de São Paulo entre os dias 02/04/2020 e 28/04/2020 com informações sobre o fluxo de vítimas entre os hospitais e os cemitérios e crematórios da cidade de São Paulo. Incluímos em nossas análises óbitos confirmados e óbitos suspeitos de COVID-19. Os principais objetivos deste relatório são: (1) descrever a estrutura do fluxo de vítimas entre localidades e (2) sugerir mudanças no fluxo com base em distâncias geográficas de maneira a evitar uma potencial sobrecarga do sistema funerário.&nbsp;Sugere-se à prefeitura da cidade de São Paulo que seja realizado um planejamento para uma potencial sobrecarga do sistema funerário (isto é, número de sepultamentos) da cidade de São Paulo com base nos resultados apresentados. Desta forma, nossos resultados reforçam a necessidade de ser adotado planejamento específico para a gestão dos casos extraordinários visualizados no contexto da pandemia. Esta previsão está baseada na análise estrutural da rede de fluxos de vítimas da COVID-19, que indica a concentração de vários locais com alta vulnerabilidade à sobrecarga do sistema. Tais locais concentram a maior quantidade de óbitos (hospitais) ou a maior concentração de sepultamentos (cemitérios ou crematórios) e tem portanto alto potencial de tornarem-se sobrecarregados por receberem muitos corpos devido ao aumento de vítimas da pandemia. Recomenda-se especial atenção à localidades da zona leste de São Paulo, que apresenta os hospitais mais vulneráveis da cidade e abriga cemitérios e crematórios que possuem papel central na rede e/ou encontram-se vulneráveis. Com base em nossa análise de otimização, sugerimos mudanças logísticas no atual fluxo de corpos de hospitais para cemitérios/crematórios de modo a não sobrecarregar o sistema funerário e minimizar os custos de transporte. Neste sentido, nossos resultados são potencialmente úteis ao aperfeiçoamento do planejamento operacional da Prefeitura Municipal de São Paulo, ratificando ou retificando ações em curso no âmbito municipal

Vulnerabilidade das microrregiões da Região Sul do Brasil à pandemia do novo coronavírus (SARS-CoV-2)

This is the first report of the ‘Observatório COVID191 - Grupo: Redes de Contágio – Laboratório de Estudos de Defesa’ for the South region of Brazil. We have combined data of confirmed cases of the new coronavirus (SARS-CoV-2) for the South available up to 17/04/2020, with structural analyses of road networks, from within and between states, to estimate the vulnerability and potential influence of the South micro-regions to propagate the disease.Este é o primeiro relatório do Observatório COVID19 - Grupo: Redes de Contágio – Laboratório de Estudos de Defesa para a região Sul do Brasil. Combinamos dados de casos confirmados do novo coronavírus (SARS-CoV-2) para o Sul, disponíveis até o dia 17/04/2020, com análises estruturais da rede de rotas rodoviárias intra e interestaduais para estimarmos a vulnerabilidade e potencial influência das microrregiões sulinas na propagação da doença