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Mutualistic interactions between plants and animals promote integration of invasive species into native communities. In turn, the integrated invaders may alter existing patterns of mutualistic interactions. Here we simultaneously map in detail effects of invaders on parameters describing the topology of both plant-pollinator (bi-modal) and plant-plant (uni-modal) networks. We focus on the invader Opuntia spp., a cosmopolitan alien cactus. We compare two island systems: Tenerife (Canary Islands) and Menorca (Balearic Islands). Opuntia was found to modify the number of links between plants and pollinators, and was integrated into the new communities via the most generalist pollinators, but did not affect the general network pattern. The plant uni-modal networks showed disassortative linkage, i.e. species with many links tended to connect to species with few links. Thus, by linking to generalist natives, Opuntia remained peripheral to network topology, and this is probably why native network properties were not affected at least in one of the islands. We conclude that the network analytical approach is indeed a valuable tool to evaluate the effect of invaders on native communities. ; Funding to AT and MN by the Spanish Ministry of Science and Education and FEDER funds of the European Union (CGL2004-0161BOS and CGL2007-61165BOS projects) is gratefully acknowledged. BP received a FPI grant by the Spanish Ministry of Science and Education and TB and JMO were supported by the Danish Science Research Council. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. ; Peer reviewed

AbstractLoss of biodiversity comprehends not only the extinction of individual species, but also the loss of the ecological interactions among them. Survival of species, continuation of ecosystem functioning in nature, and ecosystem services to humans depend on the maintenance of well-functioning networks of species interactions (e.g. plant–pollinator networks and food webs). Analyses of ecological networks often rely on biased and incomplete survey data, especially in species-rich areas, such as the tropics. We used a network inference method to reconstruct pollination data compiled from a large tropical rainforest habitat extent. To gain insight into the characteristics of plant–pollinator interactions across the region, we combined the reconstructed pollination network with species distribution modelling to obtain local pollination networks throughout the area. We explored how global network properties relate to natural forest cover and land cover heterogeneity. We found that some network properties (the sum and evenness of link weights, connectance and nestedness) are positively correlated with forest cover, indicating that networks in sites with more natural habitat have greater diversity of interactions. Modularity was not related to forest cover, but seemed to reflect habitat heterogeneity, due to the broad spatial scale of the study. We believe that the methodology suggested here can facilitate the use of incomplete network data in a reliable way and allow us to better understand and protect networks of species interactions in high biodiversity regions of the world.

© The Authors 2015. Oceanic archipelagos are threatened by the introduction of alien species which can severely disrupt the structure, function and stability of native communities. Here we investigated the pollination interactions in the two most disturbed Galápagos Islands, comparing the three main habitats and the two seasons, and assessing the impacts of alien plant invasions on network structure.We found that the pollination network structure was rather consistent between the two islands, but differed across habitats and seasons. Overall, the arid zone had the largest networks and highest species generalization levels whereas either the transition between habitats or the humid habitat showed lower values. Our data suggest that alien plants integrate easily into the communities, but with low impact on overall network structure, except for an increase in network selectiveness. The humid zone showed the highest nestedness and the lowest modularity, which might be explained by the low species diversity and the higher incidence of alien plants in this habitat. Both pollinators and plants were alsomore generalized in the hot season, when networks showed to bemore nested. Alien species (both plants and pollinators) represented a high fraction (~56 %) of the total number of interactions in the networks. It is thus likely that, in spite of the overall weak effect we found of alien plant invasion on pollination network structure, these introduced species influence the reproductive success of native ones, and by doing so, they affect the functioning of the community. This certainly deserves further investigation. ; This research is part of a larger project funded by BBVA Foundation and is also framed within project CGL-2013-44386-P financed by the Spanish Government. R.H. was supported by the Portuguese grant FCT-IF/00441/2013, and by the Marie Curie action FP7-2012-CIG-321794 ; Peer Reviewed

Data are available at Dryad Digital Repository: http://dx.doi.org/10.5061/dryad.ns1rn8psn ; Maintaining the diversity of wild bees is a priority for preserving ecosystem function and promoting stability and productivity of agroecosystems. However, wild bee communities face many threats and beekeeping could be one of them, because honey bees may have a strong potential to outcompete wild pollinators when placed at high densities. Yet, we still know little about how beekeeping intensity affects wild bee diversity and their pollinator interactions. Here, we explore how honey bee density relates to wild bee diversity and the structure of their pollination networks in 41 sites on 13 Cycladic Islands (Greece) with similar landscapes but differing in beekeeping intensity. Our large-scale study shows that increasing honey bee visitation rate had a negative effect on wild bee species richness and abundance, although the latter effect was relatively weak compared to the effect of other landscape variables. Competition for flowering resources (as indicated by a resource sharing index) increased with the abundance of honey bees, but the effect was more moderate for wild bees in family Apidae than for bees in other families, suggesting a stronger niche segregation in Apidae in response to honey bees. Honey bees also influenced the structure of wild bee pollination networks indirectly, through changes in wild bee richness. Low richness of wild bees in sites with high honey bee abundance resulted in wild bee networks with fewer links and lower linkage density. Our results warn against beekeeping intensification in these islands and similar hotspots of bee diversity, and shed light on how benefits to pollination services of introducing honey bees may be counterbalanced by detriments to wild bees and their ecosystem services. ; This research was co-financed by the European Union (European Social Fund – ESF) and Greek national funds through the Operational Program 'Education and Lifelong Learning' of the National Strategic Reference Framework (NSRF) – Research Funding Program: THALES: POL-AEGIS, Grant number MIS 376737. AL was supported by a Ramón y Cajal (RYC-2015-19034) contract from the Spanish Ministry of Science, Innovation and Universities, the Spanish State Research Agency, European Social Funds (ESF invests in your future) and the University of the Balearic Islands, and by the project CGL2017-89254-R supported by Feder funds, the Spanish Ministry of Economy and Competitiveness and the Spanish Research Agency.

Two important biological differences between oceanic and continental islands are that the former usually have lower species richness and a higher degree of taxonomic disharmony than the latter. Although there is some evidence of less complex interaction networks on oceanic islands, only a few studies have compared island communities with each other or with mainland communities. Here, we analyse the species composition and structural properties of quantitative flower visitation networks in two communities of each of two different island systems: the Canary Islands (oceanic origin) and the Balearic Islands (continental origin). We compared different network parameters to inform us about their vulnerability in the face of different types of disturbance. The number of species was greater in the Balearic than in the Canarian networks but, contrary to expectations, the total number and diversity of interactions did not differ between them. Moreover, a greater number of opportunistic species and the presence of super-generalist species on the oceanic island led to significantly higher values of quantitative connectance and nestedness relative to those on the continental island. Given that these two parameters are associated with network stability, our findings support the hypothesis that oceanic island communities are less vulnerable to perturbations than are those of continental islands, although further studies with a network approach are needed to determine whether this is a general pattern. © 2014 The Linnean Society of London. ; This study is framed within projects CGL2007-61165/BOS and CGL2010-18759/BOS financed by the Spanish Ministry of Science and Innovation. RC-U received an FPI grant from the Spanish Government (Ministry of Economy and Competitiveness and Ministry of Education, Culture and Sport) ; Peer Reviewed

The structure of pollination networks is an important indicator of ecosystem stability and functioning. Livestock grazing is a frequent land use practice that directly affects the abundance and diversity of flowers and pollinators and, therefore, may indirectly affect the structure of pollination networks. We studied how grazing intensity affected the structure of plant-flower visitor networks along a wide range of grazing intensities by sheep and goats, using data from 11 Mediterranean plant-flower visitor communities from Lesvos Island, Greece. We hypothesized that intermediate grazing might result in higher diversity as predicted by the Intermediate Disturbance Hypothesis, which could in turn confer more stability to the networks. Indeed, we found that networks at intermediate grazing intensities were larger, more generalized, more modular, and contained more diverse and even interactions. Despite general responses at the network level, the number of interactions and selectiveness of particular flower visitor and plant taxa in the networks responded differently to grazing intensity, presumably as a consequence of variation in the abundance of different taxa with grazing. Our results highlight the benefit of maintaining moderate levels of livestock grazing by sheep and goats to preserve the complexity and biodiversity of the rich Mediterranean communities, which have a long history of grazing by these domestic animals. ; The research has been co-financed by the European Union (European Social Fund—ESF) and Greek National funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF)—Research Funding Program: THALES: Investing in knowledge society through the European Social Fund ; Peer Reviewed

Understanding the dynamics of species interactions under the threats of habitat loss and fragmentation can be key to develop measures preventing further degradation of natural and agricultural systems. Agroecological knowledge and state of the art technologies can help to conciliate the often-discrepant objectives of biodiversity conservation and agricultural production. Specifically, information on the characteristics of plant-pollinator networks in agroecosystems can unveil the most efficient strategies to preserve ecosystem functionality and pollination services provision. In chapter 1, I focused on the contributions of new technology to the objective of turning agricultural landscapes increasingly compatible with biodiversity. I reviewed the applications of unmanned aerial vehicles (UAVs) in ecology and precision agriculture. I 1) identified existing applications, 2) discussed limitations and advantages of the current technology, 3) highlighted knowledge gaps and 4) proposed new applications. In chapter 2, I studied the characteristics of a plant-pollinator metanetwork of calcareous grasslands embedded in an agricultural matrix. I characterized and discussed the structural properties of the network that determine its stability and resilience to perturbations. Furthermore, I identified the traits of the most central nodes in the network. I found that the metanetwork was significantly more modular and less connected than expected by chance. This reflects the existence of many fragment-unique interactions and is an indication of poor metanetwork stability. I also demonstrated that habitat size and the diversity of land cover types in the surroundings of a grassland fragment are significant predictors of site centrality. Thus, these features can help to identify the most important fragments for metanetwork cohesiveness. Additionally, I found that the centrality of interactions depends on the pollinator size, species identity and also on the plant's habitat specialization. In chapter 3, I compared plant-pollinator networks constructed with flower visitation data to networks constructed with pollen transport data. The level of specialization of pollen transport networks was higher than that of visitation networks, as half of the interactions in the visitation networks did not occur in the pollen transport networks. This highlights the fact that visitation does not necessarily imply pollen transport, and I discussed its implications for the conservation of pollination. Considering that high specialization is known to be associated with low stability in mutualistic networks, this result has important implications for conservation. According to these findings, traditional studies on plant-pollinator networks, based on visitation data, would overestimate the stability of pollination networks. Additionally, I identified that almost a third of the total number of interactions found are difficult to spot given their low frequency, occurring only in the pollen transport networks. Finally, I found positive effects of landscape diversity on the total number and proportion of single-fragment interactions for pollen transport, but not for visitation networks. In conclusion, the protection of large and small calcareous grasslands as well as the enhancement of landscape heterogeneity was found to be essential for the maintenance of the plant-pollinator metanetwork. Furthermore, the importance of interactions among habitat specialist plants and large-bodied generalist pollinators appeared to be fundamental to connect the plant-pollinator metanetwork. Nonetheless, small solitary bees and the habitat specialist butterfly Polyommatus coridon also played a central role for the plant-pollinator networks in calcareous grasslands. By identifying the most central plants, pollinators and interactions at the metacommunity level, the information reported in this work can inform tailored management measures to protect them. Among others, I suggest considering plant species' roles in the metanetwork when applying conservation measures, such as flower strips, and landscape coordination among farmers to increase crop diversification. Moreover, I showed the great potential of UAVs to contribute to such conservation measures and to biodiversity management in agricultural landscapes. UAVs can assist in diverse tasks such as quantifying encroachment of calcareous grasslands and plant diversity monitoring. Additionally, they can contribute to farmer´s cropland management and agri-environmental schemes surveillance by governmental agencies. ; 2021-04-29

Worldwide, there is a well-documented crisis for bees and other pollinators which represent a fundamental biotic capital for wild life conservation, ecosystem function, and crop production. Among all pollinators of the world, bees (Hymenoptera: Apoidea) constitute the major group in species number and importance, followed by hover flies (Diptera: Syrphidae). The Aegean constitutes one of the world's hotspots for wild bee and other pollinator diversity including flies (mainly hover flies and bee flies), beetles, and butterflies. Despite this advantage, our present knowledge on Greek pollinators is poor, due to a lack of focused and systematic research, absence of relevant taxonomic keys, and a general lack of taxonomic experts in the country. As a result, assessments of pollinator loss cannot be carried out and the causes for the potential pollinator loss in the country remain unknown. Consequently, the desperately needed National Red Data list for pollinators cannot be compiled. This new research (2012–2015) aims to contribute to the knowledge of the pollinator diversity in Greece, the threats pollinators face, as well as the impacts these threats may have on pollination services. The research is conducted in the Aegean archipelago on >20 islands and several mainland sites in Greece and Turkey. Prime goals are: i. the assessment of bee and hover fly diversity (species, genetic); ii. their pollination services; and iii. the effects of climate change, grazing, intensive bee-keeping, fires, electromagnetic radiation on bee diversity and ecology, as well as on plant–pollinator networks. At the same time, this research contributes to the taxonomic capital in Greece and the Eastern Mediterranean, focusing on the creation of the first identification keys for pollinators, the training of new scientists, as well as the enrichment and further development of the Melissotheque of the Aegean, a permanent reference collection of insect pollinators established at the University of the Aegean. ; En todo el mundo hay una crisis bien documentada para las abejas y otros polinizadores los cuales representan un capital biótico fundamental para la conservación de la vida silvestre, la función de los ecosistemas, y la producción de cultivos. Entre todos los polinizadores del mundo, las abejas (Hymenoptera: Apoidea) constituyen el grupo principal en cuanto al número de especies y su importancia, seguido por los sírfidos (Diptera: Syrphidae). El Egeo constituye uno de los puntos importantes de diversidad de abejas silvestres y otros polinizadores del mundo, incluyendo moscas (principalmente sírfidos y bombílidos), escarabajos y mariposas. A pesar de esta ventaja, los conocimientos actuales sobre los polinizadores griegos son reducidos, debido a la falta de una investigación focalizada y sistemática, la ausencia de claves taxonómicas pertinentes, y una falta general de expertos en taxonomía en el país. Como resultado, no se pueden llevar a cabo evaluaciones de la pérdida de polinizadores y las causas de la pérdida potencial de polinizadores en el país siguen siendo desconocidas. En consecuencia, la imperiosamente necesitaba Lista Roja de datos para polinizadores no se puede compilar. Esta nueva investigación (2012-2015) tiene como objetivo contribuir al conocimiento de la diversidad de polinizadores en Grecia, enfrentarse a las amenazas para los polinizadores, así como investigar el impacto que estas amenazas pueden tener sobre los servicios de polinización. La investigación se llevará a cabo en el archipiélago del mar Egeo en más de 20 islas y en varios sitios del continente en Grecia y Turquía. Los principales objetivos son: i. la evaluación de la diversidad de abejas y sírfidos (especies, genética); ii. sus servicios de polinización, y iii. los efectos del cambio climático, el pastoreo, la apicultura intensiva, los incendios y las radiaciones electromagnéticas sobre la diversidad de abejas y la ecología, así como en las redes planta-polinizador. Al mismo tiempo, esta investigación contribuirá a la taxonomía en Grecia y el Mediterráneo Oriental, centrándose en primer lugar en la creación de las claves de identificación para polinizadores, la formación de nuevos científicos, así como el enriquecimiento y el desarrollo de la Melisoteca del Egeo, una colección de referencia permanente de los insectos polinizadores establecidos en la Universidad del Egeo. ; This research is co-financed by the European Union (European Social Fund—ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: Thales -Investing in knowledge society through the European Social Fund.

Understanding the dynamics of species interactions under the threats of habitat loss and fragmentation can be key to develop measures preventing further degradation of natural and agricultural systems. Agroecological knowledge and state of the art technologies can help to conciliate the often-discrepant objectives of biodiversity conservation and agricultural production. Specifically, information on the characteristics of plant-pollinator networks in agroecosystems can unveil the most efficient strategies to preserve ecosystem functionality and pollination services provision. In chapter 1, ...

Pollination is fundamentally important to ecosystem function and human food security. Recent reports of dramatic insect declines, and pollinator decline in particular, have increased public awareness and political motivation to act to protect pollinators. This article maps commonly proposed management interventions onto known drivers of bee decline, and identifies forage and nest site provision as a tractable management intervention that can simultaneously address multiple drivers of decline. However, it is recognized that there are gaps in the knowledge of exactly how much and which types of forage resources are necessary to support wild pollinator populations. A novel network analysis approach based on quantified floral resources and pollination services is proposed, which would illuminate the types and quantities of floral resources and pollinators necessary to maintain a diverse and abundant plant–pollinator community. The approach would also facilitate the prediction of species extinctions in plant–pollinator communities and help target conservation interventions. Finally, Oxford Plan Bee is introduced as a new, citizen-science-based project to monitor solitary bee populations, and provide empirical data to validate predictions from the proposed network approach. The over-arching aim of the described network analysis approach and the Oxford Plan Bee project is to facilitate effective, evidence-based conservation action to protect pollinators and the plants they pollinate into the future.

We investigated the plant-pollinator interactions of Passifloraceae occurring in fragments of lowland semi-deciduous Atlantic forest. We described floral biology, pollination syndromes and the pollinators of Passiflora alata, Passiflora kermesina, Passiflora suberosa, Passiflora malacophylla and Mitostemma glaziovii. We examined the robustness of the interaction networks to species loss, a plausible scenario resulting from forest fragmentation. The effects of pollination syndrome (flower size) on network robustness was also examined. Passiflora alata, P. malacophylla and P. suberosa were pollinated by bees of different corporal sizes. P. kermesina and M. glaziovii presented the highest diversity of visitors and were pollinated mainly by hummingbirds and butterflies, respectively. Through the analysis of the networks we differentiate the structures of the flower-visitor network with the 'true' plant-pollinator network. The robustness of the flower-visitor network to animal loss was generally high, but it declined when only true pollinators were included in the network. The sequential loss of plants from the flower-visitor network resulted in low robustness: the loss of key plants could have significant cascading effects on the animals feeding on them within the forest fragment. Future studies should consider the interactions between all flowering plants and animals in this habitat in order to guide conservation and management plans for these forest fragments.

Removal of invasive species often benefits biological diversity allowing ecosystems' recovery. However, it is important to assess the functional roles that invaders may have established in their new areas to avoid unexpected results from species elimination. Invasive animal-pollinated plants may affect the plant–pollination interactions by changing pollinator availability and/or behaviour in the community. Thus, removal of an invasive plant may have important effects on pollinator community that may then be reflected positive or negatively on the reproductive success of native plants. The objective of this study was to assess the effect of removing Oxalis pescaprae, an invasive weed widely spread in the Mediterranean basin, on plant–pollinator interactions and on the reproductive success of co-flowering native plants. For this, a disturbed area in central Portugal, where this species is highly abundant, was selected. Visitation rates, natural pollen loads, pollen tube growth and natural fruit set of native plants were compared in the presence of O. pes-caprae and after manual removal of their flowers. Our results showed a highly resilient pollination network but also revealed some facilitative effects of O. pes-caprae on the reproductive success of co-flowering native plants. Reproductive success of the native plants seems to depend not only on the number and diversity of floral visitors, but also on their efficiency as pollinators. The information provided on the effects of invasive species on the sexual reproductive success of natives is essential for adequate management of invaded areas. ; This work is financed by FEDER funds through the COMPETE Program and by Portuguese Foundation for Science and Technology (FCT) funds in the ambit of the project PTDC/ BIA-BIC/110824/2009, by CRUP Acc¸o˜es Integradas Luso- Espanholas 2010 with the project E10/10, by MCI-Programa de Internacionalizacio´n de la I ? D (PT2009-0068) and by the Spanish DGICYT (CGL2009-10466), FEDER funds from the European Union, and the Xunta de Galicia (INCITE09- 3103009PR). FCT also supported the work of S. Castro (FCT/ BPD/41200/2007) and J. Costa (CB/C05/2009/209; PTDC/ BIA-BIC/110824/2009). The work of V. Ferrero was supported by the Fundacio´n Ramo´n Areces.

Our premise was to understand the basic structure of the flower-flower visitor community at La Mancha in Veracruz, Mexico. We used network analyses to study the structure of this community. In particular, to analyze, (1) if flower color and shape ("as a limited portion of the traditional floral syndromes definition") were linked to the arrival of certain floral visitors, (2) if visits to flowers were generalist, specific and/or modular; and (3) which plant species, if any, in the core of the network could affect the stability of floral visitors. In order to analyze the organization of the plant-floral visitor community, we prepared network graphics using Pajek, nestedness (as NODF) with Aninhado, and modularity with the SA algorithm. The network obtained was nested suggesting that generalist species (with the most associations) were interacting with specialists (with fewer associations). Furthermore, floral visitors (Hymenoptera, Diptera, Lepidoptera and Trochiilidae) did not exhibit a particular preference for a specific flower color or shape, each pollinator group visited most flowers/colors/shapes considered. The same was similar for all 14 resulting modules. As in other studies, we suggest that pollination leans to generalization rather than to specialization. We suggest that maybe seasonality/food resource could be the factors to analyze as the next step in floral visits which may be the answer to modularity in this seasonal ecosystem.

Climate has a direct influence on crop development and final yield. The consequences of global climate change have appeared during the last decades, with increasing weather variability in many world regions. One of the derived problems is the maintenance of food supply in this unstable context and the needed changes in agricultural systems, looking for sustainable and adaptation strategies. The study was carried out from 2008 to 2017. Aerobiological data were obtained with a Lanzoni VPPS-2000 volumetric sampler, following the Spanish Aerobiological Network protocol. The pollen and flower production was studied on ten vines of the Godello grapevine cultivar. A HOBO Micro Station and a MeteoGalicia station were used to obtain meteorological information. We observed the detrimental effect of rain on airborne pollen presence, and we statistically corroborated the negative effect of high temperatures on fruit set and ripening. We developed an accurate multiple regression model to forecast the grape yield, applying a Spearman's correlation test to identify the most influential variables. The use of aerobiological and meteorological studies for crop yield prediction has been widely used in different crops that suppose important engines for economy development. This enables growers to adapt their crop management and adjust the spent resources ; This work was funded by Xunta de Galicia CITACA Strategic Partnership (Reference: ED431E 2018/07), the AGL2014-60412-R Economy and Competence Ministry of Spain Government project and the VITICAST 20190020007473 project of the Agriculture, Fisheries and Food Ministry of Spain Government. González-Fernández E. was supported by the Ministry of Sciences, Innovation and Universities (FPU grant FPU15/03343). Piña-Rey A. was supported by Xunta de Galicia Pre-doctoral Period Support Program (ED481A-2017/xxx). Fernández-González M. was supported by FCT (SFRH/BPD/125686/2016) through the HCOP-Human Capital Operational Program, financed by "Fundo Social Europeu" and "Fundos Nacionais do ...