Response of bats and nocturnal insects to urban green areas in Europe

Animal biodiversity in cities is generally expected to be uniformly reduced, but recent studies show that this is modulated by the composition and configuration of Urban Green Areas (UGAs). UGAs represent a heterogeneous network of vegetated spaces in urban settings that have repeatedly shown to support a significant part of native diurnal animal biodiversity. However, nocturnal taxa have so far been understudied, constraining our understanding of the role of UGAs on maintaining ecological connectivity and enhancing overall biodiversity. We present a well-replicated multi-city study on the factors driving bat and nocturnal insect biodiversity in three European cities. To achieve this, we sampled bats with ultrasound recorders and flying insects with light traps during the summer of 2018. Results showed a greater abundance and diversity of bats and nocturnal insects in the city of Zurich, followed by Antwerp and Paris. We identified artificial lighting in the UGA to lower bat diversity by probably filtering out light-sensitive species. We also found a negative correlation between both bat activity and diversity and insect abundance, suggesting a top-down control. An in-depth analysis of the Zurich data revealed divergent responses of the nocturnal fauna to landscape variables, while pointing out a bottom-up control of insect diversity on bats. Thus, to effectively preserve biodiversity in urban environments, UGAs management decisions should take into account the combined ecological needs of bats and nocturnal insects and consider the specific spatial topology of UGAs in each city.info:eu-repo/semantics/publishedVersio

Modelling the response of urban lichens to broad-scale changes in air pollution and climate

To create more resilient cities, it is important that we understand the effects of the global change drivers in cities. Biodiversity-based ecological indicators (EIs) can be used for this, as biodiversity is the basis of ecosystem structure, composition, and function. In previous studies, lichens have been used as EIs to monitor the effects of global change drivers in an urban context, but only in single-city studies. Thus, we currently do not understand how lichens are affected by drivers that work on a broader scale. Therefore, our aim was to quantify the variance in lichen biodiversity-based metrics (taxonomic and trait-based) that can be explained by environmental drivers working on a broad spatial scale, in an urban context where local drivers are superimposed. To this end, we performed an unprecedented effort to sample epiphytic lichens in 219 green spaces across a continental gradient from Portugal to Estonia. Twenty-six broad-scale drivers were retrieved, including air pollution and bio-climatic variables, and their dimensionality reduced by means of a principal component analysis (PCA). Thirty-eight lichen metrics were then modelled against the scores of the first two axes of each PCA, and their variance partitioned into pollution and climate components. For the first time, we determined that 15% of the metric variance was explained by broad-scale drivers, with broad-scale air pollution showing more importance than climate across the majority of metrics. Taxonomic metrics were better explained by air pollution, as expected, while climate did not surpass air pollution in any of the trait-based metric groups. Consequently, 85% of the metric variance was shown to occur at the local scale. This suggests that further work is necessary to decipher the effects of climate change. Furthermore, although drivers working within cities are prevailing, both spatial scales must be considered simultaneously if we are to use lichens as EIs in cities at continental to global scales.info:eu-repo/semantics/publishedVersio

Wild bee larval food composition in five European cities

Urbanization poses threats and opportunities for the biodiversity of wild bees. At the same time, cities can harbor diverse wild bee assemblages, partly due to the unique plant assemblages that provide resources. While bee dietary preferences have been investigated in various studies, bee dietary studies have been conducted mostly in nonurban ecosystems and data based on plant visitation observations or palynological techniques. This data set describes the larval food preferences of four wild bee species (i.e., Chelostoma florisomne, Hylaeus communis, Osmia bicornis, and O. cornuta) common in urban areas in five different European cities (i.e., Antwerp, Belgium; Paris, France; Poznan, Poland; Tartu, Estonia; and Zurich, Switzerland). In addition, the data set describes the larval food preferences of individuals from three wild bee genera (i.e., Chelostoma sp., Hylaeus sp., and Osmia sp.) that could not be identified to the species level. These data were obtained from a Europe-level study aimed at understanding the effects of urbanization on biodiversity across different cities and cityscapes and a Swiss project aimed at understanding the effects of urban ecosystems in wild bee feeding behavior. Wild bees were sampled using standardized trap nests at 80 sites (32 in Zurich and 12 in each of the remaining cities), selected following a double gradient of available habitat at local and landscape scales. Larval pollen was obtained from the bee nests and identified using DNA metabarcoding. The data provide the plant composition at the species or genus level preferred by each bee. These unique data can be used for a wide array of research questions, including urban ecology (e.g., diversity of food sources along urban gradients), bee ecology (characterization of bee feeding preferences), or comparative studies on the urban evolution of behavioral traits between urban and nonurban sites. In addition, the data can be used to inform urban planning and conservation strategies, particularly concerning flower resources (e.g., importance of exotic species and, thus, management activities). This data set can be freely used for noncommercial purposes, and this data paper should be cited if the data is used; we request that collaboration with the data set contact person to be considered if this data set represents an important part of the data analyzed in a study.info:eu-repo/semantics/publishedVersio

Apoptotic DNA degradation into oligonucleosomal fragments, but not apoptotic nuclear morphology, relies on a cytosolic pool of DFF40/CAD endonuclease

Apoptotic cell death is characterized by nuclear fragmentation and oligonucleosomal DNA degradation, mediated by the caspase-dependent specific activation of DFF40/CAD endonuclease. Here, we describe how, upon apoptotic stimuli, SK-N-AS human neuroblastoma-derived cells show apoptotic nuclear morphology without displaying concomitant internucleosomal DNA fragmentation. Cytotoxicity afforded after staurosporine treatment is comparable with that obtained in SH-SY5Y cells, which exhibit a complete apoptotic phenotype. SK-N-AS cell death is a caspase-dependent process that can be impaired by the pan-caspase inhibitor q-VD-OPh. The endogenous inhibitor of DFF40/CAD, ICAD, is correctly processed, and dff40/cad cDNA sequence does not reveal mutations altering its amino acid composition. Biochemical approaches show that both SH-SY5Y and SK-N-AS resting cells express comparable levels of DFF40/CAD. However, the endonuclease is poorly expressed in the cytosolic fraction of healthy SK-N-AS cells. Despite this differential subcellular distribution of DFF40/CAD, we find no differences in the subcellular localization of both pro-caspase-3 and ICAD between the analyzed cell lines. After staurosporine treatment, the preferential processing of ICAD in the cytosolic fraction allows the translocation of DFF40/CAD from this fraction to a chromatin-enriched one. Therefore, the low levels of cytosolic DFF40/CAD detected in SK-N-AS cells determine the absence of DNA laddering after staurosporine treatment. In these cells DFF40/CAD cytosolic levels can be restored by the overexpression of their own endonuclease, which is sufficient to make them proficient at degrading their chromatin into oligonucleosome-size fragments after staurosporine treatment. Altogether, the cytosolic levels of DFF40/CAD are determinants in achieving a complete apoptotic phenotype, including oligonucleosomal DNA degradation

LOOKING AT CITIES THROUGH NOVEL LENSES: STUDYING URBAN BIODIVERSITY ACROSS SPATIAL AND ECOLOGICAL SCALES

Land-use change and intensification are main drivers of global biodiversity decline. Urban areas are rapidly expanding worldwide, representing a major threat for biodiversity. Nonetheless, cities are increasingly recognised as ecosystems on their own, harbouring often a considerably high biodiversity, being a major force of eco-evolutionary change, and in turn, providing a wide array of ecosystem functions and contributions to people. Despite an already long history of research, there are still important questions that remain elusive in urban ecology particularly concerning the effects of socio-ecological drivers on urban biodiversity patterns and ecological processes, for example diet preferences, species distributions and interspecific competition. Furthermore, although invertebrate species represent the majority of taxa inhabiting cities, they have been much less investigated than plants and birds, and thus, the diversities patterns for many groups in urban ecosystems are poorly understood. This thesis aimed at exploring the influence of different socio-ecological drivers on different aspects of urban biodiversity (e.g. diversity patterns, species distribution, trait variation, and trophic and competitive interactions) across spatial scales and ecological levels of organisation. To do so, different methodological tools, including macroecological analyses, next-generation sequencing techniques and individual trait-based approaches, have been used to better elucidate the effects of urban socio-ecological drivers on ecological processes and urban biodiversity patterns. Each of the three chapters of this thesis is set at a different spatial scale and ecological level of organisation. Chapter I is part of the European project BioVEINS, and includes 80 study sites in five European cities (i.e. Antwerp, Belgium; Paris, France; Poznan, Poland; Tartu, Estonia; Zurich, Switzerland) distributed following gradients of urban intensity and available habitat, where solitary wild bees and their larval pollen were sampled. Chapter II is part of the project ZuriDiverCity and represents a compilation of four urban ecology studies conducted in the city of Zurich, with 252 study sites representing the most common types of urban greens areas (e.g. parks, brownfields, green roofs, gardens) distributed along multiple urban intensity gradients and data of 1446 animal species from 12 animal groups. Finally, Chapter III is part of the project City4Bees and includes data on managed and wild bees in 23 domestic gardens varying in local habitat features and in the position within the urban intensity gradient in the city of Zurich. Chapter I studies the larval diet preferences of four widespread solitary bee species (i.e. Chelostoma florisomne, Osmia bicornis, Osmia cornuta and Hylaeus communis) using pollen metabarcoding, and, in addition, investigates how larval feeding specialisation affects the distribution of the four wild bee species within urban intensity gradients. It shows that there are different feeding specialisation strategies that can be successful in urban ecosystems allowing bees to exploit a variable part of the urban floral resources. These feeding specialisation strategies are not limited to broad generalism, but also included intermediate levels of generalism, with a certain degree of diet conservatism at the plant family or genus level (in O. bicornis and O. cornuta), and strict specialisation to a single plant genus with few species but widely common in urban habitats (in C. florisomne). However, at the same time, larval feeding specialisation influences the occupation of habitat patches and distribution within urban intensity gradients, and broader diets result in less sensitivity to urban intensity. Broad generalist H. communis was the least sensitive bee to urban intensity. Interestingly, the analyses of its larval diet reveals plant host shifts from a more herbaceous-based diet to a more tree-based diet triggered by losses in the amount of available herbaceous habitat, showing the important role of street trees in providing alternative resources for some wild bee species. Therefore, identifying larval floral preferences could be helpful for identifying key plant taxa and traits for bee survival and for improving strategies to develop bee-friendly cities. Chapter II investigates the ecological properties of urban biodiversity in the city of Zurich using machine learning predictive models and occurrence and abundance data from 1446 species belonging to 12 different animal groups. The occurrence and abundance distribution patterns of the taxonomic groups resemebled those from non-urban ecosystems. Specifically, urban diversity is composed by a very reduced group of hyperdominant and hyperwidespread species in the city while the vast majority of species are scarce and locally- occurring. Furthermore, the application of predictive models revealed that only species with intermediate abundances and occurrences were spatially structured along urban gradients, with decreasing numbers with increasing urban intensity. Strikingly, rare species were less sensitive to urban gradients and their numbers kept constant even in the most utbanised areas of the city. Overall, urban green areas with lower management regimes tended to contain higher species richness of most of the studied groups. The use of predictive models in urban ecosystems, specifically when producing continuous citywide biodiversity maps, is a promising tool to address both ecological questions and inform urban planning and management. Chapter III examines the interplay of resource availability and beekeeping intensity at local and landscape scales in shaping the diversity of urban wild bees in urban gardens in the city of Zurich. By collecting six functional traits and incorporating individual trait variability, the feeding niche partitioning between the wild bee community and the honeybee population was calculated at each site. Lower resource availability at the local scale negatively affected wild bee species richness, whereas lower resource availability at the landscape scale increased honeybee densities at the study sites. In turn, feeding niche partitioning decreased in sites with lower resource availability at the landscape scale (and thus, with larger honeybee densities) and decreased as well with lower resource availability at the local scale, due to a reduction in the number of wild bee species, in particular those that where more functionally similar to honeybees. Conversely, beekeeping intensity at local and landscape scales did not have a direct effect neither on feeding niche partitioning nor on wild bee species richness. Hence, monitoring and management of resource availability is critical to support wild bee diversity and manage urban beekeeping. This thesis provides novel insights on the effects of socio-ecological drivers on selected biodiversity patterns and ecological processes at different scales and ecological level of organisation, through the application of new methodological tools. The application of new analytical tools, such macroecological models or next-generation sequencing technique can pose a great opportunity to revist classical urban ecology questions but with novel lenses. Furthermore, the different results compiled provide a basis to ecologically inform management and planning of urban habitats, specifically to minimize the effects of anthropogenic activities and secure the natural capital of urban ecosystems

Challenging the sustainability of urban beekeeping using evidence from Swiss cities

Urban beekeeping is booming, heightening awareness of pollinator importance but also raising concerns that its fast growth might exceed existing resources and negatively impact urban biodiversity. To evaluate the magnitude of urban beekeeping growth and its sustainability, we analysed data on beehives and available resources in 14 Swiss cities in 2012–2018 and modelled the sustainability of urban beekeeping under different scenarios of available floral resources and existing carrying capacities. We found large increases in hives numbers across all cities from an average 6.48 hives per km2 (3139 hives in total) in 2012 to an average 8.1 hives per km2 (6370 in total) in 2018 and observed that available resources are insufficient to maintain present densities of beehives, which currently are unsustainable.ISSN:2661-800

Spatial mismatch between wild bee diversity hotspots and protected areas

Wild bees are critical for multiple ecosystem functions but are currently threatened. Understanding the determinants of the spatial distribution of wild bee diversity is a major research gap for their conservation. We modeled wild bee a and ss taxonomic and functional diversity in Switzerland to uncover countrywide diversity patterns and determine the extent to which they provide complementary information, assess the importance of the different drivers structuring wild bee diversity, identify hotspots of wild bee diversity, and determine the overlap between diversity hotspots and the network of protected areas. We used site-level occurrence and trait data from 547 wild bee species across 3343 plots and calculated community attributes, including taxonomic diversity metrics, community mean trait values, and functional diversity metrics. We modeled their distribution with predictors describing gradients of climate, resource availability (vegetation), and anthropogenic influence (i.e., land-use types and beekeeping intensity). Wild bee diversity changed along gradients of climate and resource availability; high-elevation areas had lower functional and taxonomic a diversity, and xeric areas harbored more diverse bee communities. Functional and taxonomic ss diversities diverged from this pattern, with high elevations hosting unique species and trait combinations. The proportion of diversity hotspots included in protected areas depended on the biodiversity facet, but most diversity hotspots occurred in unprotected land. Climate and resource availability gradients drove spatial patterns of wild bee diversity, resulting in lower overall diversity at higher elevations, but simultaneously greater taxonomic and functional uniqueness. This spatial mismatch among distinct biodiversity facets and the degree of overlap with protected areas is a challenge to wild bee conservation, especially in the face of global change, and calls for better integrating unprotected land. The application of spatial predictive models represents a valuable tool to aid the future development of protected areas and achieve wild bee conservation goals.ISSN:0888-8892ISSN:1523-173

Floral species evenness is the major driver of wild bee communities in urban gardens

Urban gardens have the potential to contribute to urban bee biodiversity. However, studies considering the effects of habitat amount and floral resources on bees using a functional approach, are largely lacking in Latin America, in particular in urban environments, where the potential competitive interactions between honeybees and wild bees deserve further attention. We evaluated how bee abundance and diversity, both taxonomic (richness, evenness) and functional (richness, evenness, and divergence of traits), are related to habitat amount in urban gardens (patch size, green cover in the surroundings), and the abundance and diversity of flowers (taxonomic and functional). We also examined the effect of the abundance of honeybees on urban wild bee communities. We selected 13 gardens within Córdoba city (Argentina) along an urbanization gradient based on vegetation cover, where we surveyed bee-flower interactions. We selected flower (i.e. morphology, color, and phenology) and bee (i.e. morphology, sociality, and diet) traits considered essential to plant-pollinator interactions to estimate flower and bee functional diversity, respectively. Bee taxonomic and functional diversity in urban gardens strongly depended on the floral species evenness, whereas the functional floral diversity and patch size, as well as the habitat amount at the landscape scale, did not significantly affect bee diversity. Moreover, the abundance of honeybees, once controlled by floral species evenness, did not influence the taxonomic structure of wild bee communities. Our results highlight that urban gardens can support functionally diverse bee communities, especially those with evenly distributed flower species.Fil: Rossi Rotondi, Bruno Ariel. 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; ArgentinaFil: Casanelles Abella, Joan. Swiss Federal Research Institute WSL; SuizaFil: Fontana, Simone. Swiss Federal Research Institute WSL; Suiza. Albert Ludwigs University of Freiburg; AlemaniaFil: Moretti, Marco. Swiss Federal Research Institute WSL; SuizaFil: Videla, Martin. 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; ArgentinaFil: Fenoglio, Maria Silvina. 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; Argentin

Altres ajuts: MEC programa Ramón y Cajal Chromatin Collapse during Caspase-dependent Apoptotic Cell Death Requires DNA Fragmentation Factor, 40-kDa Subunit-/Caspase-activated Deoxyribonuclease-mediated 3'-OH Single-strand DNA Breaks.

Apoptotic nuclear morphology and oligonucleosomal double-strand DNA fragments (also known as DNA ladder) are considered the hallmarks of apoptotic cell death. From a classic point of view, these two processes occur concomitantly. Once activated, DFF40/CAD endonuclease hydrolyzes the DNA into oligonucleosomal-size pieces, facilitating the chromatin package. However, the dogma that the apoptotic nuclear morphology depends on DNA fragmentation has been questioned. Here, we use different cellular models, including MEF CAD-/- cells, to unravel the mechanism by which DFF40/CAD influences chromatin condensation and nuclear collapse during apoptosis. Upon apoptotic insult, SK-N-AS cells display caspase-dependent apoptotic nuclear alterations in the absence of internucleosomal DNA degradation. The overexpression of a wild-type form of DFF40/CAD endonuclease, but not of different catalytic-null mutants, restores the cellular ability to degrade the chromatin into oligonucleosomal-length fragments. We show that apoptotic nuclear collapse requires a 3'-OH endonucleolytic activity, even though the internucleosomal DNA degradation is impaired. Moreover, the alkaline unwinding electrophoresis and the ISEL/ISNT assays reveal that the apoptotic DNA damage observed in the DNA ladder-deficient SK-N-AS cells is characterized by the presence of single-strand nicks/breaks (SSBs). Apoptotic SSBs can be impaired by DFF40/CAD knockdown, abrogating nuclear collapse and disassembly. In conclusion, the highest order of chromatin compaction observed in the later steps of caspase-dependent apoptosis relies on DFF40/CAD-mediated DNA damage by generating 3'-OH ends in single-strand rather than double-strand DNA nicks/breaks

A dataset of the flowering plants (Angiospermae) in urban green areas in five European cities

This article summarizes the data of a survey of flowering plants in 80 sites in five European cities and urban agglomerations (Antwerp, Belgium; greater Paris, France; Poznan, Poland; Tartu, Estonia; and Zurich, Switzerland). Sampling sites were selected based on a double orthogonal gradient of size and connectivity and were urban green areas (e.g. parks, cemeteries). To characterize the flowering plants, two sampling methodologies were applied between April and July 2018. First, a floristic inventory of the occurrence of all flowering plants in the five cities. Second, flower counts in sampling plots of standardized size (1 m2) only in Zurich. We sampled 2146 plant species (contained in 824 genera and 137 families) and across the five cities. For each plant species, we provide its origin status (i.e. whether the plants are native from Europe or not) and 11 functional traits potentially important for plant-pollinator interactions. For each study site, we provide the number of species, genera, and families recorded, the Shannon diversity as well as the proportion of exotic species, herbs, shrubs and trees. In addition, we provide information on the patch size, connectivity, and urban intensity, using four remote sensing-based proxies measured at 100- and 800-m radii.ISSN:2352-340