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Climate change is forcing the redistribution of life on Earth at an unprecedented velocity1,2. Migratory birds are thought to help plants to track climate change through long-distance seed dispersal3,4. However, seeds may be consistently dispersed towards cooler or warmer latitudes depending on whether the fruiting period of a plant species coincides with northward or southward migrations. Here we assess the potential of plant communities to keep pace with climate change through long-distance seed dispersal by migratory birds. To do so, we combine phenological and migration information with data on 949 seed-dispersal interactions between 46 bird and 81 plant species from 13 woodland communities across Europe. Most of the plant species (86%) in these communities are dispersed by birds migrating south, whereas only 35% are dispersed by birds migrating north; the latter subset is phylogenetically clustered in lineages that have fruiting periods that overlap with the spring migration. Moreover, the majority of this critical dispersal service northwards is provided by only a few Palaearctic migrant species. The potential of migratory birds to assist a small, non-random sample of plants to track climate change latitudinally is expected to strongly influence the formation of novel plant communities, and thus affect their ecosystem functions and community assembly at higher trophic levels., The ‘Molecular Ecology Laboratory’ (LEM–EBD–CSIC; ISO9001:2015 and ISO14001:2015 certifications) and the ‘Research Unit of Biodiversity’ (UO–CSIC–PA) provided logistical support for molecular analyses. We thank L. Viesca and E. Cires for laboratory assistance, and J. M. Varela for the bird illustrations. Barcoding data were obtained within an Individual Fellowship from the Marie Sklodowska-Curie Actions (H2020-MSCA-IF-2014-656572: MobileLinks) and supported by a GRUPIN grant from the Regional Government of Asturias (IDI/2018/000151). ‘King Jaume I’ awarded to A.T. supported data collation during two postdoctoral contracts. J.P.G.-V. is supported by a Spanish ‘Ramón y Cajal’ fellowship (RYC-2017-22095) and a grant from the Spanish MICINN (PID2019-104922GA-I00/AEI/10.13039/501100011033). B.R. is supported by a Spanish ‘Juan de la Cierva Incorporación’ fellowship (IJCI-2017-33475). R.H.H. is funded by the Portuguese Foundation for Science and Technology (UID/BIA/04004/2020). B.I.S. is supported by a Royal Commission for the Exhibition of 1851 Research Fellowship. W.J.S. is funded by Arcadia.

Keystone species are disproportionately important for ecosystem functioning (1,2). However, while all species engage in multiple interaction types with other species, the importance of keystone species is often defined based on a single dimension of their Eltonian niche (3), that is, one type of interaction (e.g., keystone predator). Therefore, it remains unclear whether the importance of keystone species is unidimensional or if it extends across interaction types. We conducted a meta-analysis of tripartite interaction networks to examine whether species importance in one dimension of their niche is mirrored in other niche dimensions, and whether this is associated with interaction outcome, intimacy, or species richness. We show that keystone species importance is positively associated across multiple ecological niche dimensions, independently of species’ abundance, and find no evidence that multidimensionality of keystone species is influenced by the explanatory variables. We propose that the role of keystone species extends across multiple ecological niche dimensions, with important implications for ecosystem resilience and conservation.Significance StatementKeystone species are often identified by focusing on a single type of interaction (e.g., predation, pollination, herbivory) which contrasts with the multiple roles that species play in biological communities. We conducted a meta-analysis of 18 tripartite interaction networks to explore if keystonness is correlated across the multiple dimensions of species Eltonian niches. Our results suggest that species importance tends to span across multiple interaction types, independently from abundance, which can be key to understand community resilience and collapse in face of multiple threats.

Seed dispersal is key to the persistence and spread of plant populations. Because the majority of plant species rely on animals to disperse their seeds, global change drivers that directly affect animals can cause cascading impacts on plant communities. In this review, we synthesize studies assessing how disperser loss alters plant populations, community patterns, multitrophic interactions, and ecosystem functioning. We argue that the magnitude of risk to plants from disperser loss is shaped by the combination of a plant species’ inherent dependence on seed dispersal and the severity of the hazards faced by their dispersers. Because the factors determining a plant species’ risk of decline due to disperser loss can be related to traits of the plants and dispersers, our framework enables a trait-based understanding of change in plant community composition and ecosystem functioning. We discuss how interactions among plants, among dispersers, and across other trophic levels also mediate plant community responses, and we identify areas for future research to understand and mitigate the consequences of disperser loss on plants globally., This work was supported by the National Socio-Environmental Synthesis Center’s Postdoctoral Fellowship to E.C.F. under funding received from the National Science Foundation (DBI1639145), the Alexander von Humboldt Foundation Fellowship to I.D., and the Spanish Ministry of Science to A.T. (project CGL2017-88122-P).

Understanding the mechanisms by which non-native plants can attract pollinators in their new geographical zones is important because such species infiltrate native communities and can disrupt native ecological interactions. Despite the large number of studies assessing how invasive plants impact plant–pollinator interactions, the specific comparison of pollination interactions between native and non-native plant pairs has received much less attention. Here we focused on four coexisting co-flowering pairs of common native and non-native species, both with abundant flowers but different floral traits, and asked: (1) to what extent native and non-native plants share pollinator species, and whether the non-native plants attract a different set of pollinators, (2) whether the most shared pollinators are the most frequent floral visitors and the most generalized in their interactions, and (3) how much of the variation in the diversity and frequency of pollinator species between native and non-native plant species can be explained by floral trait dissimilarity and flower abundance. Direct pollinator observations revealed that the plant pairs shared a low fraction (0–33%) of insect species, i.e., non-native plants tended to acquire a different set of pollinators than their native counterparts. The most shared pollinators in each plant pair were the most common but not the most generalized species, and non-native species attracted both generalized and specialized pollinators. Corolla length at opening and flower abundance showed to be important in determining the differences in flower visitation rate between natives and non-natives. Our findings support the general pattern that non-native species have no barriers at the pollination stage to integrate into native communities and that they may attract a different assemblage of pollinators relative to those that visit native plants with which they coexist., This study was framed within project GLC2017-88122-P financed to AT by the Spanish Ministry of Science, Innovation, and Universities.

Although most plants depend on different animals for pollination and seed dispersal, sometimes the same animal species provides both functions, being thus involved in what has been termed a ‘double mutualism’. Very little is known on the effectiveness of such species as both pollinators and seed dispersers, and even less on the intraspecific level differences at the contribution of an animal mutualist to plant fitness. In this study, we focused on the interaction between a Mediterranean shrub Cneorum tricoccon (Rutaceae) and the Balearic lizard Podarcis lilfordi (Lacertidae) in order to assess: 1) the role of this lizard as a legitimate pollinator of the plant (previously thought to be exclusively insect‐pollinated), and 2) the intraspecific variation in the use of flowers and fruits by lizard individuals, comparing males, females and juveniles. We further evaluated whether lizards show different fruit size selection depending on sex and age, with potential consequences for seed germination. Lizards visited more flowers and selected more hermaphrodite flowers than insects did, leading to relative increases in both fruit and seed set. Interestingly, female and juvenile lizards were the main flower visitors, whereas males were the main fruit consumers. Males selected the largest fruits (bearing the largest seeds) though this did not increase seed germination, which was only ca 15%. We concluded that P. lilfordi acts as a legitimate pollinator of C. tricoccon and, thus, confirm that this system constitutes a new case of double mutualism, especially common in island compared to mainland systems. Moreover, our findings show a large variation among conspecific individuals in their role as either pollinators or seed dispersers, with potential implications for plant reproductive success. Our study, therefore, highlights the importance of evaluating plant–animal interactions at the intraspecific level, and calls for more in‐depth studies on the consequences of such intraspecific variation., This work is framed within projects CGL2013‐44386‐P and CGL2017‐88122‐P, and FF is funded by a PhD fellowship (BES‐2014‐068207), all financed by the Spanish Government.

Introduced plants become decoupled from their usual pollinators and by relying on resident pollinator species or other reproductive strategies become established in new areas, spread and, eventually, invade. Here, using breeding system experiments, we studied the reproductive biology of the bird-pollinated South American species Nicotiana glauca across native and non-native areas, both inside and outside the range of flower-visiting birds. In the native range, where the species is visited by hummingbirds, open cross-pollinated flowers set as many seeds and almost as many fruits as open pollination controls, suggesting that pollinators make a major contribution to reproductive success. In South Africa, the flowers were pollinated by sunbirds which, although less efficiently, also contributed to N. glauca reproduction, replacing hummingbirds. In contrast, in Mallorca, where nectar feeding birds are absent, fruit production in open cross-pollinated flowers was near zero, and significantly lower than in open pollination controls, suggesting that reproduction is almost entirely by autonomous self-pollination. Hand-pollination experiments showed that the species is self-compatible throughout its range. Pollinator exclusion experiment showed that N. glauca relies on self-pollination only in pollinator poor areas, where plants have a much higher capacity for autonomous self-pollination than elsewhere. A reduction in anther-stigma distance does not seem to account the higher self-pollination capacity in the non-native environment without pollinators. Despite probable evolutionary adaptation, and flexibility in pollinator association and mating system, seed production in the introduced range was somewhat pollen limited, suggesting that the mismatch between N. glauca and its novel pollination environment might retard invasion., Funding for this research was provided by the National Research Council of Argentina (CONICET), the National Ministry of Science and Technology of Argentina, the Department of Science and Technology of South Africa and the Spanish Research Council (CSIC).

Almond trees are one of the most important crops in the Balearic Islands. The pollination of almonds is limited to the activity of insects, and cross-pollination is necessary for fruit development. Currently, honey bees and wild bee populations are declining considerably due to multiple causes, such as the use of pesticides, diseases and habitat loss. An alternative to increase the almond production is the use of commercial pollinators. In this long-term (3 years) study, the effect of the introduction of Bombus terrestris colonies on almond production was evaluated in two orchards. Two experimental designs were carried out to study the best management of this pollinator. For 2 years, all bumble bee colonies were placed in the middle of the plot and during the last year, the bumble bee colonies were distributed homogenously in the plot. Fruit set and the foraging behaviour of bumble bees during the blossoming period was determined, and the effect of different environmental variables on the visitation rate of bumble bees was assessed by means of a generalized linear mixed model (GLMM). Moreover, for the first time, the spatial distribution of fruit set was evaluated. Our results show that fruit set was significantly higher in the fields where B. terrestris had been introduced than in the control plots. This increased production resulted in a positive economic balance for the farmer. Moreover, bumble bees showed to prefer trees in a southwest orientation that were close to their colony. The activity of bumble bees showed to be significantly influenced by wind speed (the higher the speed the more flowers are visited by B. terrestris) and time after flowering (visitation rate decreased with days after flowering). In order to improve its management and obtain the highest possible almond production, it is important to understand the activity and behaviour of this pollinator., The authors would like to thank farmers of Son Marrano and Son Pons to have allowed us to realize the field work in their farms, and Fons de Garantia Agrària i Pesquera de les Illes Balears (FOGAIBA) BIA 7/17 to had funded this experiment. Elsevier Language Editing Services for editing this manuscript. Also, to the reviewers and the editor for their comments with which the paper has improved. Special thanks to students of the Laboratory of Zoology for their collaboration in the field.

Islands harbor a considerable portion of global biodiversity and endemic biota, and also are the recipients of the largest proportional numbers of alien invaders. Such invaders may jeopardize the performance of native species, through either their direct or indirect effects. In this study, we investigated the reproductive ecology of the endemic scrambling perennial herb Canarina canariensis in remnants of the former thermosclerophyllous woodland of Tenerife (Canary Islands), assessing how two widespread alien invasive species, the honeybee (Apis mellifera) and the black rat (Rattus rattus), affect its reproductive success. Apis mellifera visits its flowers whereas the black rat consumes both its flowers and fruits. Here, we compared the pollination effectiveness of different animal guilds (vertebrates vs insects) by means of selective exclosures and determined the level of floral herbivory. Three bird species (Phylloscopus canariensis, Cyanistes teneriffae and Sylvia melanocephala), a lizard (Gallotia galloti) and two insects (A. mellifera and the butterfly Gonepteryx cleobule) were the main flower visitors. Phylloscopus canariensis was the most frequent visitor in the early flowering season whereas A. mellifera predominated in the flowers during mid and late flowering periods. Birds increased fruit set, whilst lizards and insects had a negligible effect. Rats consumed about 10% of the flowers and reduced fruit set to one third. Besides contributing little to plant reproduction, A. mellifera might interfere with bird pollination by depleting flowers of nectar. We conclude that both alien species can threaten C. canariensis reproduction and hence population sustainability in the thermosclerophyllous vegetation. Apis mellifera, in particular, may become especially detrimental if apiculture keeps expanding, or if this bee becomes active earlier in the season due to global warming., Julia Jaca was funded by a predoctoral fellowship from the Ministerio de Educación, Cultura y Deporte [FPU13/05880] and by the unemployment benefit from the Ministerio de Trabajo, Migraciones y Seguridad Social; and the study was framed within a project financed by the Ministerio de Economía, Industria y Competitividad [CGL2013-44386-P], granted to Anna Traveset.

Interaction frequency is the most common currency in quantitative ecological networks, although interaction quality can also affect benefits provided by mutualisms. Here, we evaluate if interaction quality can modify network topology, species' role and whether such changes affect community vulnerability to species loss. We use a well-examined study system (bird–lizard and fleshy-fruited plants in the ‘thermophilous' woodland of the Canary Islands) to compare network and species-level metrics from a network based on fruit consumption rates (interaction frequency, IF), against networks reflecting functional outcomes: a seed dispersal effectiveness network (SDE) quantifying recruitment, and a fruit resource provisioning network (FRP), accounting for the nutrient supply of fruits. Nestedness decreased in the FRP and the SDE networks, due to the lack of association between fruit consumption rates and 1) nutrient content and; 2) recruitment at the seed deposition sites, respectively. The FRP network showed lower niche overlap due to resource use complementarity among frugivores. Interaction evenness was lower in the SDE network, in response to a higher dominance of lizards in the recruitment of heliophilous species. Such changes, however, did not result in enhanced vulnerability against extinctions. At the plant species level, strength changed in the FRP network in frequently consumed or highly nutritious species. The number of effective partners decreased for species whose seeds were deposited in unsuitable places for recruitment. In frugivores, strength was consistent across networks (SDE vs IF), showing that consumption rates outweighed differences in dispersal quality. In the case of lizards, the increased importance of nutrient-rich species resulted in a higher number of effective partners. Our work shows that although frequency strongly impacts interaction effects, accounting for quality improves our inferences about interaction assembly and species role. Thus, future studies including interaction outcomes from both partners' perspectives will provide valuable insights about the net effects of mutualistic interactions., This study is framed within projects CGL2007-61165/BOS and CGL2017-88122-P from the Spanish Ministry of Science and supported by FEDER funds from the European Union. We are grateful to Guido Jones, currently funded by the Cabildo de Tenerife under the TFinnova Programme supported by MEDI and FDCAN, for revising the English and making useful recommendations to improve it. We are especially grateful to Airam Rodríguez, David Padilla, Beatriz Rumeu, Daniel González, Benito Pérez, Yurena Gavilán, Patricia Marrero, Elsa Bonnaud and Concepción Nieves, who helped at different stages of the study. AGC benefitted from a JAE-PRE fellowship from the Spanish National Research Council (CSIC) and was funded by the island council, Cabildo de Tenerife, under the identification mark “Tenerife 2030” (P. INNOVA 2016-2021).

Indirect effects arise when one species influences how another species interacts with a third. Pollinator-mediated indirect effects are widespread in many plant communities and are often not restricted to plant species pairs. An analytical framework does not exist yet that allows for the evaluation of indirect effects through shared pollinators in a community context as well as their consequences for plant fitness. We used network indices describing pollinator sharing to assess the extent to which plant species affect and are affected by others in a pollination network from a species-rich dune community. For 23 plant species, we explore how these indices relate to plant fecundity (seeds/flower) over two years. We further linked plant traits and indices to uncover functional aspects of pollinator-mediated indirect interactions. Species frequently visited by shared pollinators showed higher fecundity and exhibited traits that increase pollinator attraction and generalization. Conversely, species whose shared pollinators frequently visited other plants had lower fecundity and more specialized traits. Thus, pollinator sharing benefited some species while others suffered reproductive disadvantages, consistent with competition. The framework developed here uses network tools to advance our understanding of how pollinator-mediated indirect interactions influence a species’ relative reproductive success at the community level., P.J.B. was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP; 2016/06434-0 and 2018/02996-0) and Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ; 201.867/2020). This study was supported by project CGL2017-89254-R, financed by the Ministerio de Ciencia, Innovación y Universidades (MCIU), the Agencia Estatal de Investigación (AEI), and the European Regional Development Funds (ERDF; Call 2017). A.L. was supported by a postdoctoral contract cofunded by the Regional Government of the Balearic Islands and the European Social Fund 2014–2020 and by a Ramón y Cajal contract from the Spanish Ministry of Economy and Competitiveness. A.T. was supported by project CGL2017-88122-P, financed by the Spanish Ministry of Economy and Competitiveness and FEDER founds (Call 2017). Servei de Protecció d’Espècies, Espais de Natura Balear (Conselleria d’Agricultura, Medi Ambient i Territori), provided permission to work at the study site.

Many frugivorous animals act simultaneously as seed predators and dispersers, and shifts in the abundance and mean phenotype of the frugivore population can alter the prevalence of antagonistic versus mutualistic interactions with seeds. Here, we evaluated how a reduction in the abundance and species richness of large-bodied frugivorous fishes affects their interactions with plants in a Neotropical floodplain. Fisheries selectively harvest large frugivorous fishes, which are the most effective seed dispersers. Thus, functional extinctions of fish mutualists can cascade to secondary extinctions of plants and their biotic associates, and ecosystem-level change. We evaluated functional responses of wetland communities to changes in fish body size by modelling the robustness of plant–frugivore networks to different extinction scenarios, using fish body size as a functional trait influencing seed dispersal and seed predation. We built ecological networks for frugivory, seed dispersal and seed predation. All networks lacked modularity and showed reduced nestedness compared with randomized networks. The three networks indicated that frugivorous fish have wide niches and low to intermediate degree of specialization. Network robustness to extinction of frugivorous fish decreased with selective loss of large individuals. Synthesis and applications. We predict that reductions in the abundance of large-bodied fish species will enhance the dominance of plant species with small seeds and decrease plant diversity. The functionally most important species in our networks are the most susceptible to overfishing. Therefore, sustainable management in these ecosystems needs to contribute to protecting interactions and, consequently, ecological and evolutionary processes related to maintaining biodiversity in vast wetland forests., This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Brazil (CAPES, Finance Code 001, to J.M.A.), the Eppley Family Foundation (to J.A. and S.B.C.), National Geographic (to J.A. and S.B.C.), SESC Pantanal (to all authors), the University of Georgia (to J.A.), Mississippi State University (to S.B.C., MISZ-081700), the Brazilian National Council for Scientific and Technological Development (CNPq, to J.M.A. and J.P.), the Long-Term Ecological Research Program—PELD—Site 12 and the Pantanal Research Center (CPP, to J.P. and J.M.A) and Ministry of Science, Technology and Innovation (MCTI, to J.P.).

Diverse biotic interactions between non-native plant species and other species from all taxonomic groups are crucial mediators of the dynamics of plant invasions. This chapter reviews the key hypotheses in invasion ecology that invoke biotic interactions to explain aspects of plant invasion dynamics. We examine the historical context of these hypotheses and assess the evidence for accepting or rejecting their predictions. Most hypotheses invoke antagonistic interactions, mainly competition, predation, herbivory interactions and the role of pathogens. Only in the last two decades have positive (facilitative/mutualistic) interactions been explicitly included in invasion biology theory (as in ecological theory in general). Much information has accumulated in testing hypotheses relating to biotic resistance and Enemy Release Theory, although many of the emerging generalizations are still contentious. There is growing consensus that other drivers of plant invasion success, such as propagule pressure and disturbance, mediate the outcome of biotic interactions, thereby complicating our ability to make predictions, but these have rarely been assessed in both native and adventive ranges of non-native invasive species. It is also widely acknowledged that biogeographic comparisons, more than common garden experiments, are needed to shed light on many of the contradictory results. Contrasting findings have also emerged in exploring the roles of positive interactions. Despite strong evidence that such interactions are crucial in many communities, more work is needed to elucidate the factors that influence the relative importance of positive and negative interactions in different ecosystems. Different types of evidence in support of invasional meltdown have emerged for diverse habitats and across spatial scales. In light of increasing evidence that biotic indirect effects are crucial determinants of the structure, dynamics and evolution of ecological communities, both direct and indirect interactions involving native and non-native species must be considered to determine how they shape plant invasion patterns and the ecological impacts of non-native species on recipient communities. Research that examines both biotic interactions and the factors that mediate their strength and alter interaction outcomes is needed to improve our ability to predict the effects of novel interactions between native and non-native species, and to envisage how existing invaded communities will respond to changing environmental conditions. Many opportunities exist for manipulating biotic interactions as part of integrated control strategies to reduce the extent, density and impacts of non-native plant invasions. These include the introduction of species from the native range of the non-native plant for biological control, diverse manipulations of plant - herbivore interactions and many types of interaction to enhance biotic resistance and steer vegetation recovery following non-native plant control.

Many vertebrate species act as both plant pollinators and seed-dispersers, thus interconnecting these processes, particularly on islands. Ecological multilayer networks are a powerful tool to explore interdependencies between processes; however, quantifying the links between species engaging in different types of interactions (i.e. inter-layer edges) remains a great challenge. Here, we empirically measured inter-layer edge weights by quantifying the role of individually marked birds as both pollinators and seed-dispersers of Galápagos plant species over an entire year. Although most species (80%) engaged in both functions, we show that only a small proportion of individuals actually linked the two processes, highlighting the need to further consider intra-specific variability in individuals' functional roles. Furthermore, we found a high variation among species in linking both processes, i.e. some species contribute more than others to the modular organization of the multilayer network. Small and abundant species are particularly important for the cohesion of pollinator seed-dispersal networks, demonstrating the interplay between species traits and neutral processes structuring natural communities., This research was undertaken within projects CGL2015-67865-P and CGL2017-88122-P funded by the Ministerio de Economía y Competitividad, Spain. R.H. and S.T. were financed by the Portuguese Foundation for Science and Technology (FCT) contracts: UID/BIA/04004/2019 and CEECIND/00135/2017, respectively. The manuscript was edited by Guido Jones, currently funded by the Cabildo de Tenerife, under the TFinnova Programme supported by MEDI and FDCAN funds

[Premise] Opportunistic nectar‐feeders may act as effective pollinators; nonetheless, we still lack information on whether these opportunistic species differ in their pollination effectiveness from specialized nectarivorous vertebrates and insects. Many nectar specialists have coevolved with the plants on which they feed; therefore, we would expect higher pollination effectiveness in specialists than in opportunistic feeders. Here, we assessed quantity and quality components of pollination effectiveness in specialist and opportunistic vertebrate nectarivores and insects, focusing on three plants from the Seychelles: Thespesia populnea, Polyscias crassa, and Syzygium wrightii., [Methods] We determined the quantity component (QNC) of pollination effectiveness with pollinator observations, and the quality component (QLC) by measuring fruit and seed set resulting from single visits by each pollinator. To detect potential negative effects of invasive ants on native plant‐pollinator interactions, we classified pollinator visits (quantity component) as disturbed (>6 ants/30 min) vs. undisturbed., [Results] All focal plants were visited by insects, and vertebrate specialist and opportunist nectarivores, yet their pollination effectiveness differed. Flying insects were the most effective pollinators of T. populnea. The other two plants were most effectively pollinated by vertebrates; i.e., sunbirds (nectar specialists) in S. wrightii and Phelsuma geckos (nectar opportunists) in P. crassa, despite marked variation in QNC and QLC. Ant presence was associated with lower pollinator visitation rate in P. crassa and S. wrightii., [Conclusions] Our study highlights the importance of all pollinator guilds, including opportunist nectarivorous vertebrates as pollinators of island plants, and the vulnerability of such interactions to disruption by nonnative species., This work was part of projects CGL2013‐44386‐P and CGL2017‐88122‐P awarded to A. T. and financed by the Spanish Government. F. F. was funded by the Spanish Government with a Ph.D. fellowship (BES‐2014‐ 068207). C. N. K.‐B. was supported by funding from the German Research Foundation (DFG; KA 3349/2‐1 and KA 3349/3‐1).

1. One very conspicuous sign that warming is affecting the ecology of butterflies are the phenological advances occurring in many species. Moreover, rising temperatures are having a notable impact – both negative and positive – on population abundances. To date, patterns have generally been analysed at species level without taking into account possible differences between populations, which, when they are noted, are mostly attributed to large-scale climate differences across a latitudinal gradient. 2. We use a long-term database (18 years) of butterflies from five sites of the island of Menorca (Balearic Islands, Spain) to investigate how phenology and population dynamics have been affected by climate warming during the past two decades. 3. Both species' phenology and abundance respond differently to warming at a local scale depending on the season. Rising temperatures in spring give rise to greater advancement of the phenology, whereas warming affects population abundance negatively in summer. Additional variability of responses among sites suggests that habitats are involved in the modulation of the aforementioned seasonal effect. 4. We discuss how the effects of temperature could be partially offset in more inland habitats such as forests or deep ravines, especially the latter which represent particularly fresh and humid environments. The positive effect of temperature on ravine populations during the summer suggests that butterflies disperse across habitats as a response to rising temperatures during the season. This dispersal behaviour as a response to warming could be especially important in island ecosystems where the possibilities of modifying altitudinal or latitudinal distributions are often severely limited., PC is funded by a PhD fellowship financed by the Govern de les Illes Balears (FPI-CAIB-2018). This work is framed within project GLC2017-88122-P financed by the Spanish Ministry of Science and Innovation to AT. The Catalan Butterfly Monitoring Scheme is funded by the Departament de Territori i Sostenibilitat de la Generalitat de Catalunya.

Wild pollinators are a valuable natural resource for crops, as they often increase their production and quality. For this reason, there is currently a great interest in the development of management and conservation tools that help to maintain a wide variety of wild pollinators in agro-systems. To achieve this, it becomes a priority to study the diversity of wild pollinators in relevant crops as well as the local and landscape characteristics that benefit them. The almond tree (Prunus dulcis) is a crop of high economic interest, with a large dependence on pollinators due to the self-incompatibility of most of its varieties and, thus, it is very vulnerable to pollinator losses. By using field data and habitat characterization of 18 almond fields in Mallorca Island (Spain), we assessed how the abundance and diversity of pollinators varied with local and landscape characteristics (at 1 and 2 km buffer zones) of the fields, and how those affected almond production (fruit set). Almond trees were mostly pollinated by honeybees, but they were also visited by a large number of wild pollinators. The percentage of natural area in the 2 km buffer zones increased both pollinator-species richness and honeybee visits. At the field level, the flower community in the ground positively influenced almond production, both directly and indirectly by increasing the diversity of wild pollinators. Pollinator-species diversity directly increased fruit production but was negatively affected by honeybee abundance, which suggests that a high density of honeybees might result in negative effects on almond production through competition with wild pollinators. Management strategies to improve almond production might include favoring wild pollinators through the maintenance of natural habitats surrounding crop fields, and preserving the flowering herb community that occurs spontaneously in the groundcover of almond fields in Mediterranean areas.

Beltran, R., Traveset, A. 2018. Networks of interaction between flowers and hymenopters in two coastal communities. Effects of habitat loss. Ecosistemas 27(2): 102-114. Doi.: 10.7818/ECOS.1409 Pollination is a key process for the functioning of the ecosystem. The environmental crisis is affecting pollinators around the world. The study of the structure and dynamics of pollination networks can give us information on species conservation and on the importance of pollination as an ecosystem service. In this work we analyzed the pollination networks of hymenoptera in two coastal localities of the island of Mallorca, one of them affected by habitat loss. A set of parameters was obtained describing the structure of interaction networks at both community and species level. In addition, we evaluated the species richness, diversity, and conservation status of hymenopterans presumably with greater functional relevance in each community (the most general and least selective). Both communities showed low connectance, a relatively high specialization and a low niche overlap, which suggests a high fragility to disturbances. In fact, the loss of habitat caused a decrease in the richness of plant species that resulted in a lower diversity of hymenopterans and plant-pollinator interactions. The community affected by the perturbation showed to be less robust to future disturbances than the unaltered community. The analyzed parameters allowed assessing the ecological role of the most important bees and wasps in the community and their behaviour at the temporal scale. With such results, we suggest specific management measures for each locality.

Premise of the study Relying on floral traits to assess pollination systems has been shown to underestimate the ecological service that novel mutualisms can provide. Although vertebrates with opportunistic food habits are common on islands, usually feeding upon flowers of entomophilous species (ES), little is known about how effective they are as pollinators. In a previous study, we had reported that native insectivorous and frugivorous Galapagos birds commonly visit ES flowers, without assessing whether they act as pollinators. Here we investigate this by focusing on three typically ES (Cryptocarpus pyriformis, Waltheria ovata, Cordia lutea) and one mostly ornithophilous species (OS), Opuntia echios. Methods The quantitative component (QNC: the product of floral visit frequency and number of flowers contacted) and qualitative components (QLC: fruit and seed set, fruit length, and mass and proportion of seedling emergence) of pollination effectiveness of birds was compared with that of insects. Key results Birds were not quantitatively important pollinators compared to insects. However, selective exclusion experiments in the four plant species revealed that all qualitative components of fitness improved when both birds and insects visited the flowers. Our study is the first to confirm pollination effectiveness of ES by native opportunistic birds. Conclusions The Galapagos pollination systems are probably more generalized than previous data suggested and, given that ES dominate the flora of this archipelago, we argue that, contrary to expectation, birds might have an important role in maintaining the reproductive success and diversity of plant communities.

Autochthonous plant species are heavily threatened by the increasing spread of invasive insects. The spatial distribution of invasive species' hosts is likely to play a pivotal role in the establishment and further expansion of the invading species; more specifically, distance and density dependent (DDD) processes linked to plant spatial arrangement are crucial in determining susceptibility to attack, but they have usually been overlooked in invasive research. We take a spatially explicit approach to evaluate potential DDD processes in the interaction between Paysandisia archon, a tropical lepidopteran recently introduced in Spain, and the endemic Mediterranean dwarf palm (Chamaerops humilis) in Mallorca (Balearic Islands). Specifically, we used spatial marked point pattern analyses, which allowed testing whether DDD processes affect attack probability and intensity on three dwarf palm populations corresponding to three different invasion phases (i.e., infestation core, early expansion, and expansion front). Our approach also allowed evaluation of whether and how intrinsic palm traits (size, sex) alter the proneness to P. archon attack over a range of spatial scales. The occurrence and nature of DDD effects on C. humilis performance varied largely among localities. At the infestation core, our analyses revealed positive density dependence, i.e., reduced damage at high densities or proximity to conspecific neighbors. By contrast, the early expansion locality showed negative density dependence of C. humilis performance, whereas at the expansion front, there was no evidence of DDD effects. Larger palms were consistently more prone to P. archon attack than small ones up to scales of 50 m. We found no evidence that palm sex altered the probability of attack by P. archon. Our results highlight the importance of spatially explicit analyses for assessing invasive events and point to the need of early interventions and prioritizing management efforts on larger palms in order to guarantee the conservation of autochthonous dwarf palm populations., This work was financed by the Conselleria de Medi Ambient of the Balearic Government and coordinated by AT. AL was supported by a postdoctoral contract co-funded by the Regional Government of the Balearic Islands and the European Social Fund 2014–2020. JMF was funded by a Portuguese FCT Grant (IF/00728/2013).

Environmental gradients in alpine systems may lead to differences in both abiotic conditions and species interactions in very short distances. This may lead to reproductive and phenotypic changes in plants to enhance fitness in each environment. In this study, we explored how the Central Andean Viola maculata responds to the elevation gradient, where it is distributed, with an expected increase in water availability and a decrease in pollinator availability with elevation. We hypothesized that: (1) plants would be more water-stressed at low elevations; (2) investment in and success of cleistogamous flowers (closed, self-pollinated) would increase with elevation; and (3) correlation patterns between floral and vegetative traits would vary along the gradient according to changes in biotic/abiotic selection pressures across sites. We partially confirmed the inverse gradient of water stress with elevation, with V. maculata populations in the lowest site experiencing lower soil moisture and showing thicker leaves and lower stomatal conductance. Cleistogamy was more prevalent and successful at the highest site, thus confirming the hypothesis of maintenance of a mixed-mating system as reproductive assurance. Correlation patterns between flower and leaf size differed across sites, with stronger vegetative–floral correlation at the lower sites and a weak correlation at the highest site. This finding disagrees with the notion of pollinators as drivers of correlation between floral and vegetative traits. Our study shows how a narrow gradient in an alpine system may affect not only reproductive and physiological responses in plants, but also floral and vegetative covariances.

The annual export of the Mediterranean seagrass ( Posidonia oceanica ) litter to adjacent beaches and coastal dunes was quantified by examining the fortnight evolution of seagrass beach-cast volume on two beaches in the NW Mediterranean (Son Real and Es Trenc, Mallorca Island, Spain) for two years and analyzing the wind speed and direction obtained from the closest Meteorological Spanish Agency surface weather stations. The decomposition stage of the deposits was examined by analyzing the total hydrolysable amino acids, its percentage distribution and derived degradation indexes. Prevalent winds exceeding 6 m s −1 , the coastline morphology and type of terrestrial vegetation determine the annual dynamics of the seagrass beach-cast. In the most protected beach (Son Real) the seagrass beach-cast remained nearly stationary during the two studied years while it exhibited wide annual fluctuations in the less protected one (Es Trenc). The amounts of P. oceanica wrack washed on Son Real and Es Trenc beaches, respectively, were estimated at 309 kg DW m coastline −1 yr −1 and 1359 kg DW m coastline −1 yr −1 . They supplied between 20 kg CaCO 3 m coastline −1 yr −1 and 47 kg CaCO 3 m coastline −1 yr −1 . Between 54% (Son Real) and 70% (Es Trenc) of seagrass beach-cast, respectively accounting for 1.5 kg N m coastline −1 yr −1 and 8.6 kg N m coastline −1 yr −1 , were annually exported from the beaches to adjacent dune systems. Our results reveal that Mediterranean seagrass meadows might be an important source of materials, including sand and nutrients, for adjacent terrestrial systems, able to support their functioning.

© 2017 The Authors., The effect of population size on population genetic diversity and structure has rarely been studied jointly with other factors such as the position of a population within the species’ distribution range or the presence of mutualistic partners influencing dispersal. Understanding these determining factors for genetic variation is critical for conservation of relict plants that are generally suffering from genetic deterioration. Working with 16 populations of the vulnerable relict shrub Cneorum tricoccon throughout the majority of its western Mediterranean distribution range, and using nine polymorphic microsatellite markers, we examined the effects of periphery (peripheral vs. central), population size (large vs. small), and seed disperser (introduced carnivores vs. endemic lizards) on the genetic diversity and population structure of the species. Contrasting genetic variation (H: 0.04–0.476) was found across populations. Peripheral populations showed lower genetic diversity, but this was dependent on population size. Large peripheral populations showed high levels of genetic diversity, whereas small central populations were less diverse. Significant isolation by distance was detected, indicating that the effect of long-distance gene flow is limited relative to that of genetic drift, probably due to high selfing rates (F = 0.155–0.887), restricted pollen flow, and ineffective seed dispersal. Bayesian clustering also supported the strong population differentiation and highly fragmented structure. Contrary to expectations, the type of disperser showed no significant effect on either population genetic diversity or structure. Our results challenge the idea of an effect of periphery per se that can be mainly explained by population size, drawing attention to the need of integrative approaches considering different determinants of genetic variation. Furthermore, the very low genetic diversity observed in several small populations and the strong among-population differentiation highlight the conservation value of large populations throughout the species’ range, particularly in light of climate change and direct human threats., Funding was provided by the Spanish Ministry for Innovation and Science with the grants Consolider Montes (CSD2008_00040) and VULGLO (CGL2010‐22180‐C03‐03) provided to FV, and the Minsitry of Economy and Competitiveness, grant ECOMETAS (CGL2014‐53840‐REDT) and Junta de Andalucía Excellence project to Juan Arroyo and AT.

The ongoing biodiversity crisis entails the concomitant loss of species and the ecological services they provide. Global defaunation, and particularly the loss of frugivores, may negatively affect the seed dispersal of fleshy-fruited plant species, with predictable stronger impacts in simplified communities such as those on oceanic islands. However, logistical difficulties have hindered the experimental and theoretical need to disentangle the roles of species identity, richness (i.e. number of species) and abundance. Consequently, studies to date have focused exclusively on the loss of species richness leaving us largely ignorant regarding how species identity and abundance affect the loss of ecosystem functions. Here, we applied a network approach to disentangle the effects of disperser abundance, richness and identity on the seed dispersal service provided by frugivores to the Galapagos plant community. We found that both abundance and richness of the dispersers significantly affect the function of seed dispersal and that richness becomes increasingly important as disperser abundance declines. Extinction simulations revealed that the order of species loss has profound implications to the plant community. On the one hand, abundant generalist dispersers like the Galapagos lizards, can mitigate the loss of specialized dispersers. On the other hand, specific threats affecting key dispersers can lead to the rapid collapse of the community-level dispersal services. Our results suggest that the identity of the disperser species lost can have a large effect on the number of plant species dispersed, and generalist species are essential to the persistence of the community dispersal service. Both abundance and species richness of seed dispersers are key and synergistic drivers of the number of plant species dispersed. Consequently, the coupled negative effect of population declines and species extinctions in frugivore assemblages may lead to an accelerated loss of the seed dispersal function. plain language summary is available for this article., We also thank the European Union Marie Curie Action (FP7‐PEOPLE‐2012‐CIG‐ 321794), the Portuguese Foundation for Science and Technology (IF/00441/2013). This study is framed within a biodiversity project in the Galapagos Islands, partially financed by BBVA Foundation (Spain) and the projects CGL2012‐C02‐01 and CGL2013‐44386‐P funded by Ministerio de Economía y Competitividad (Spain).

Pollination is a valuable ecosystem service, and plant–pollinator interactions in particular are known to play a crucial role in conservation and ecosystem functioning. These mutualisms, like other ecological interactions, are currently threatened by different drivers of global change, mainly habitat loss, fragmentation, or modification of its quality. Most studies so far have focused on the impact of such disturbances on particular species interactions and we thus need more empirical evidence on the responses at a community-level. Here we evaluated how habitat loss influenced the pattern of interactions between plants and their flower visitors in a coastal dune marshland community. Using data from four years (2008–2011), we assessed the effect of a large disturbance in the area (occurring in 2010) that represented the loss of more than 50% of the vegetation cover. We found a considerable decrease in species richness and abundance of flower visitors, which resulted in a lower number of interactions after the disturbance. Not all functional groups, however, responded similarly. Contrary to the expected from previous findings, bees and wasps were less negatively influenced than beetles, flies and ants, possibly due to their higher movement capacity. Species interactions in the community were more specialized after habitat loss, resulting in a lower level of network nestedness and a higher modularity. At a species level, the number of flower visitors per plant decreased after the disturbance, and plants were visited by less abundant flower visitors. Our findings lead us to predict that the overall plant–flower visitor network became less robust and resilient to future perturbations. However, the fact that each functional group responds distinctly to disturbances makes it more difficult to foresee the final consequences on community composition and ecosystem functioning.

Special Issue: Animal‐plant interactions., Lizards have been reported as important pollinators on several oceanic islands. Here we evaluate the potential role of Galápagos lava lizards (Microlophus spp.) as pollinators across their radiation. Over 3 years, we sampled pollen transport by 9 lava lizard species on the 10 islands where they are present, including 7 single‐island endemics. Overall, only 25 of 296 individuals sampled (8.4%) transported pollen of 10 plant species, the most common being Prosopis juliflora, Exodeconus miersii, Sesuvium sp. and Cordia leucophlyctis. At least 8 of these plant species were native, and none were confirmed as introduced to the archipelago. Despite the low overall proportion of individuals carrying pollen, this was observed in 7 of the nine lizard species, and on 8 of the ten main islands (Española, Fernandina, Floreana, Isabela, Marchena, Pinta, Santa Cruz and Santiago), suggesting that this is a widespread interaction. The results reported here support the potential role of lava lizards as pollinators across their radiation, although they may represent a relatively modest contribution when compared with birds and insects. However, we cannot discard that lizards may be ecologically significant for particular plant species and ecosystems given the specific climatic condition and functional diversity of each island., This study is framed within the projects CGL2013-44386-P and CGL2015-67865-P funded by the Ministerio de Economía y Competitividad (Spain). We thank the Charles Darwin Foundation, especially Diana Flores and Patricia Jaramillo and the Galápagos National Park, especially Galo Quezada and Carlos Vera (research permit numbers: PC-46-14, PC-20-15, PC-22-16), for offering us information and logistic support.

Despite it is widely accepted that intrapopulation variation is fundamental to ecological and evolutionary processes, this level of information has only recently been included into network analysis of species/population interactions. When done, it has revealed non-random patterns in the distribution of trophic resources. Nestedness in resource use among individuals is the most recurrent observed pattern, often accompanied by an absence of modularity, but no previous studies examine bipartite modularity. We use network analysis to describe the diet composition of the Balearic endemic lizard Podarcis lilfordi in 2 islets at population and individual levels, based on the occurrence of food items in fecal samples. Our objectives are to 1) compare niche structure at both levels, 2) characterize niche partition using nestedness and modularity, and 3) assess how size, sex, season, and spatial location influence niche structure. At population-level niche width was wide, but narrow at the level of the individual. Both islet networks were nested, indicating similar ranking of the food preferences among individuals, but also modular, which was partially explained by seasonality. Sex and body size did not notably affect diet composition. Large niche overlap and therefore possibly relaxed competition were observed among females in one of the islets and during spring on both islets. Likewise, higher modularity in autumn suggests that higher competition could lead to specialization in both populations, because resources are usually scarce in this season. The absence of spatial location influence on niche might respond to fine-grained spatio-temporally distribution of food resources. Behavioral traits, not included in this study, could also influence resource partitioning., This work is framed within projects CGL2017-88122-P and BFU2009-09359 financed by the Spanish Government.

Nocturnal pollination plays an important role in sexual plant reproduction but has been overlooked, partially because of intrinsic difficulties in field experimentation. Even less attention has received the effect of within-inflorescence spatial position (distal or proximal) on nocturnal pollinators of columnar plants, despite numerous studies examining the relationship between such position and reproductive success. Woody endemic Echium simplex possesses large erect inflorescences bearing thousands of flowers which are visited by a wide array of diurnal and nocturnal animals. In this study, we identified nocturnal visitors and compared their pollination effectiveness with that of diurnal pollinators in different inflorescence sections by means of selective exclosures in NE Tenerife (Canary Islands). Nocturnal visitors included at least ten morphospecies of moths (such as Paradrina rebeli and Eupithecia sp.), two coleopteran species (mainly Alloxantha sp.), neuropterans (Chrysoperla carnea), dictyopterans (Phyllodromica brullei), dermapterans (Guanchia sp.) and julidans (Ommatoiulus moreletii). In general, plants excluded from pollinators set less fruits than open-pollination (control) plants which set fruits homogeneously across sections. Diurnally pollinated plants set more fruit in their upper parts whereas nocturnally pollinated plants set fruit in both upper and bottom sections. We conclude that although the frequency and diversity of diurnal pollinators is far higher than that of nocturnal pollinators, both exhibit different foraging behaviour that generates complementary effects on the reproductive success of E. simplex., Julia Jaca was funded by a predoctoral fellowship from the Ministerio de Educación, Cultura y Deporte (FPU13/05880) and by the unemployment benefit from the Ministerio de Trabajo, Migraciones y Seguridad Social. The study was framed within a project financed by the Ministerio de Economía, Industria y Competitividad (CGL2017-88122-P) to Anna Traveset.

Non-native plants rarely escape damage by herbivores. Instead, upon arrival in a new region, they begin to acquire new enemies, replacing those they have lost during their migration. These herbivores can include both natives to the new region and species that have themselves been accidentally or deliberately introduced from elsewhere, potentially including examples originating from the invader's original range. Shifts of new enemies from other hosts can occur over a range of timescales, depending in part on whether evolutionary change is required, but are likely to be faster for plants that are widespread and phylogenetically related to a herbivore's original host, and faster for generalist herbivores than for specialists. The occurrence of herbivores is not necessarily uniform across an invader's range; instead, they may be less diverse or abundant in host populations that are geographically or ecologically marginal, though existing evidence is mixed. Collectively, these new suites of herbivores can affect the growth and fitness of invaders, both directly by damaging them and indirectly by attacking their competitors. Studies comparing the demographic consequences of herbivory for successful vs unsuccessful invaders may help to clarify how often such impacts limit invasiveness. The view that an invader enters 'enemy-free' space is inaccurate; instead, persistence and spread of non-native plants often may be affected by the novel and changing assemblage of herbivores that they acquire within their new distribution.

Most plant species rely on, or benefit from, animal pollination. Therefore, pollination interactions are expected to play a key role in the reproduction and invasion success of non-native plants in their new areas. Understanding this role will allow us to better predict certain plant invasions. Also, it will allow us to explore the potential of invasion management measures based on disrupting or avoiding pollination interactions. In this chapter we review the available information on reproductive systems and their degree of dependence on animal-mediated pollination of non-native plant species. We review the characteristics of resident pollinators feeding on non-native plants and the different environmental setups that allow or impede non-native plants to reproduce in their new areas. Finally, we explore the scarce literature on invasion management measures based on disrupting pollination interactions and discuss their potentiality. Evidence so far shows that animal pollination does not usually act as an effective barrier to invasion. Most introduced plants are able to receive suitable pollination service from resident pollinators, while others are able to minimize their reliance on pollinators through different mechanisms (e.g. selfing or asexual reproduction). The environmental settings where the introduction occurs (for instance, the presence of neighbours with similar or dissimilar flower morphologies), can play an important role on the success or failure of non-native plants overcoming reproductive barriers. Although it seems that most introduced plants do not face pollination barriers, we consider that, for certain species, the disruption or avoidance of pollination interactions as control or prevention measures deserve further exploration.

Pollination is thought to be under positive density‐dependence, destabilising plant coexistence by conferring fitness disadvantages to rare species. Such disadvantage is exacerbated by interspecific competition but can be mitigated by facilitation and intraspecific competition. However, pollinator scarcity should enhance intraspecific plant competition and impose disadvantage on common over rare species (negative density‐dependence, NDD). We assessed pollination proxies (visitation rate, pollen receipt, pollen tubes) in a generalised plant community and related them to conspecific and heterospecific density, expecting NDD and interspecific facilitation due to the natural pollinator scarcity. Contrary to usual expectations, all proxies indicated strong intraspecific competition for common plants. Moreover interspecific facilitation prevailed and was stronger for rare than for common plants. Both NDD and interspecific facilitation were modulated by specialisation, floral display and pollinator group. The combination of intraspecific competition and interspecific facilitation fosters plant coexistence, suggesting that pollination can be a niche axis maintaining plant diversity., This work was supported by FAPESP (grants 2016/06434‐0 and 2018/02996‐0 to P.J.B.), CNPq (grants 436335/2018‐2 to M.W. and 302781/2016‐1 to M.S.) and CAPES (Ph.D. scholarship to N.S.S., Financial Code 001).

Due to drastic changes in pollinators between native and invaded habitats, we might expect that pollinator-mediated selection on floral traits of alien plants differ from that in their native ranges. Here, through geometric morphometric tools and phenotypic selection analyses, we examined whether adaptation in flower shape and length occurred in Nicotiana glauca as a response to pollinator selection in contrasting pollination environments. We assessed populations of this plant species in the native range (South America), where plants depend on hummingbird pollination, and in two invaded areas, one where sunbirds act as pollinators (South Africa), and another where nectar feeding birds are absent and reproduction is entirely by autonomous self-pollination (Mallorca, Spain). Corolla length and shape varied significantly among pollination environments. Non-native sites were less variable and their range of variation fell within the native range of variation. Flower length in native populations and in a South African population matched the bill length of their respective pollinators. In contrast with the straight floral tubes in the native range, both non-native areas had significantly curved tubes. Curvature may improve the fit with the curved bills of sunbirds in South Africa (versus straight beaks of hummingbirds) and may enhance self-pollination in Mallorca, but this similarity between invaded areas may equally be due to drift and a shared colonization route. We found spatial variation in selection acting on corolla length but not on corolla shape. Overall, selection patterns were not consistent with floral trait variation. Although some results are consistent with both drift and selection, our study suggests that population divergence in flower shape and length is more likely the result of long-term diversifying pollinator-driven selection, which is difficult to detect by studying a single selection event., AAC, ANS, SBV and VP acknowledge the National Research Council of Argentina (CONICET) and the Universidad Nacional de Córdoba (UNC) as researchers. This work was supported by FONCyT (PICT 2015-3089; PICT-2011-0837) to ANS, the Department of Science and Technology of South Africa (438 75946) and the Spanish Ministry of Economy and Competitiveness (CGL2013-44386-P).

Habitat loss and fragmentation are recognized as affecting the nature of biotic interactions, although we still know little about such changes for reptilian herbivores and their hindgut nematodes, in which endosymbiont interactions could range from mutualistic to commensal and parasitic. We investigated the potential cost and benefit of endosymbiont interactions between the spur-thighed tortoise (Testudo graeca L.) and adult oxyurid nematodes (Pharyngodonidae order Oxyurida) in scrublands of southern Spain. For this, we assessed the association between richness and abundance of oxyurid species with tortoises’ growth rates and body traits (weight and carapace length) across levels of habitat loss (low, intermediate and high). Furthermore, by using an intrapopulation ecological network approach, we evaluated the structure and diversity of tortoise–oxyurid interactions by focusing on oxyurid species infesting individual tortoises with different body traits and growth rates across habitats. Overall, tortoise body traits were not related to oxyurid infestation across habitats. Oxyurid richness and abundance however, showed contrasting relationships with growth rates across levels of habitat loss. At low habitat loss, oxyurid infestation was positively associated with growth rates (suggesting a mutualistic oxyurid–tortoise relationship), but the association became negative at high habitat loss (suggesting a parasitic relationship). Furthermore, no relationship was observed when habitat loss was intermediate (suggesting a commensal relationship). The network analysis showed that the oxyurid community was not randomly assembled but significantly nested, revealing a structured pattern for all levels of habitat loss. The diversity of interactions was lowest at low habitat loss. The intermediate level, however, showed the greatest specialization, which indicates that individuals were infested by fewer oxyurids in this landscape, whereas at high habitat loss individuals were the most generalized hosts. Related to the latter, connectance was greatest at high habitat loss, reflecting a more uniform spread of interactions among oxyurid species. At an individual level, heavier and larger tortoises tended to show a greater number of oxyurid species interactions. We conclude that there is an association between habitat loss and the tortoise–oxyurid interaction. Although we cannot infer causality in their association, we hypothesize that such oxyurids could have negative, neutral and positive consequences for tortoise growth rates. Ecological network analysis can help in the understanding of the nature of such changes in tortoise–oxyurid interactions by showing how generalized or specialized such interactions are under different environmental conditions and how vulnerable endosymbiont interactions might be to further habitat loss., The Dirección General de Gestión del Medio Natural de la Junta de Andalucía (SGB/FOA/AFR) and the Delegación General de Medio Natural de la Comunidad Autónoma de la Región de Murcia (AUT/ET/UND/48/2010) granted permission to sample the tortoises and nematodes.

Herbivores may directly or indirectly affect plant attractiveness to pollinators. Although several studies have reported on these effects, there is yet no general consensus on the strength and sign of such interactions or their contingency on herbivory features such as the plant tissue attacked. We performed a meta-analysis of studies testing for effects of herbivores on floral traits, plant attractiveness to pollinators, and plant reproductive success. We also assessed whether herbivore effects depended on the plant tissue attacked by herbivores and if real or simulated herbivory was used. We found an overall significant negative effect of herbivores on floral traits, plant attractiveness to pollinators, and plant reproductive success. These effects were, however, contingent on the plant tissue attacked and on whether real or simulated damage was used. Real floral and leaf, but not root, herbivores showed detrimental effects on floral traits and plant attractiveness to pollinators. In addition, real leaf, but not floral or root herbivory, lowered plant reproductive success. Contrastingly, simulated leaf and floral herbivory showed no effect on any of the response variables. These findings help move forward our understanding of the strength and directionality of herbivore effects on plant attractiveness to pollinators and their underlying mechanisms., This research was financially supported by a Regional Government of Galicia Grant (IN607D 2016/001), a Spanish National Research Grant (AGL2015‐70748‐R), and the Ramón y Cajal Research Programme (RYC‐2013‐13230) to XM.

[Premise] The endangered shrub Daphne rodriguezii (Thymelaeaceae) is endemic to the Balearic island of Menorca, where fragmentation and severe population decline are ongoing threats to this taxon. We developed a set of microsatellite markers to analyze the fine-scale genetics of its few extant populations., [Methods and Results] Fifteen microsatellite markers were obtained through Illumina high-throughput sequencing and tested in two populations. Twelve of these loci showed no evidence of null alleles and were highly polymorphic, with a mean number of 8.3 alleles per locus. Levels of observed and expected heterozygosity ranged from 0.100 to 0.952 and from 0.095 to 0.854, respectively. Seven to nine of these loci were successfully amplified in five other Daphne species., [Conclusions] This set of markers provides a useful tool for investigating the factors driving fine-scale population structure in this threatened species, and it represents a novel genetic resource for other European Daphne species., J.C.I. was funded by a GRUPIN research grant from the Regional Government of Asturias (Ref.: IDI/2018/000151), and C.G.‐V. was supported by a Vicenç Mut postdoctoral fellowship awarded by the Govern de les Illes Balears–Conselleria d'Innovació, Recerca i Turisme. The study was funded by the Ministerio de Economía, Industria y Competitividad (project Islet‐Foodwebs CGL2017‐88122‐P).

[Aim] To assess whether the reduced nutritional resources available for pollinators due to plant community simplification along an elevational plant-diversity gradient changes pollinator niche breadth and richness. Additionally, we evaluated how body size and proboscis length of pollinators shifted along the gradient, and whether these changes were related to pollinator niche breadth, [Location] An elevational gradient (2,350–3,520 m a.s.l.) on the oceanic high-mountain strato-volcano of El Teide (Tenerife, Canary Islands), [Taxon] Flowering plant and pollinator species, [Methods] We compared quantitative plant–pollinator networks along the plant-diversity gradient. We calculated a set of niche-based topological metrics that capture the degree of specialization, niche breadth and niche overlap. Furthermore, we obtained β-diversity measures and the proportion of replacement and richness components, [Results] There was an overall decline in species richness of pollinators with increasing elevation. This decline was mainly driven by the loss of species along the elevational gradient, which conformed a nested subset pattern. The whole network showed less specialization, greater connectance and lower modularity towards the summit. At high elevations, pollinators were more generalized and less selective in their flower choice, showing a greater trophic niche breadth compared to pollinators at lower elevations. Mean body size of pollinators increased with elevation, and species body size and proboscis length were positively associated with the number of plant species visited, [Main conclusions] Overall, results indicated that the elevational gradient filters pollinator species, probably according to their thermal tolerance and ability to exploit a wide range of trophic resources. The finding that pollinators become more generalized and opportunistic at higher elevations is a novel result, which may have implications for new research into how ecological networks vary over environmental gradients. From an applied perspective, our results highlight the importance of considering the spatial variation of species assemblages when aiming to construct functionally reliable interaction networks along environmental gradients., C.L.R. was supported by a Juan de la Cierva post‐doctoral fellowship (FJCI‐2015‐24712) and J.S. by a grant from the Gobierno Balear (CAIB) and co‐financed by Fondo Social Europeo (ESF). This work is framed within the projects: CGL2017‐88122‐P (Ministero de Economía y Competitividad‐Spain) and 785/2012 (Proyectos de Parques Nacionales‐Spain).

Original Research Megafauna extinctions often lead to the disruption of plant-animal interactions, such as the seed-disperser mutualisms, which might entail severe consequences for plant populations and entire communities. Interestingly, the contemporary persistence of anachronistic plant species might be possible thanks to surrogate dispersers or seed dispersal “rescuers”. We know very little on how these relevant functional replacements are contributing to the performance of present-day plant-frugivore networks. The dwarf palm Chamaerops humilis L. is a Mediterranean endemism with fleshy fruits and typically dispersed by mammals. Despite its ecological importance and wide distribution in some of the Mediterranean islands, no information exists about its seed dispersal on these depauperated-fauna systems. In this study, we aim at identifying and quantifying the relative importance of introduced frugivores on the island of Mallorca (Balearic Islands), where no native terrestrial mammals exist. Specifically, we assess for the first time the seed dispersal effectiveness (SDE) for C. humilis on islands; we evaluate the quantitative component by fecal and regurgitation sampling surveys, and the qualitative component by means of seed germination experiments and seedling growth measures. Introduced goats (Capra hircus L.) and pine martens (Martes martes L.) were the local mammal fruit consumers of C. humilis identified in our study sites. Results suggest that goats are much more important quantitatively than pine martens, due to the high number of fruits handled in each foraging bout and their extremely high abundance on the island. However, pine marten-ingested seeds showed the highest final seedling emergence success and seedling growth, thus its qualitative contribution on C. humilis seed dispersal is higher than that of goats. Overall, SDE was almost 9-fold higher for goats than for pine martens. We conclude that these two non-native mammal species are effective seed dispersers of C. humilis in this and probably other Mediterranean islands, where humans led to the extinction of its native seed dispersers, as it was probably the case of the goat-like Myotragus balearicus in the Balearic Islands info:eu-repo/semantics/publishedVersion

Many Mediterranean beaches accumulate wrack of Posidonia oceanica L. leaves and rhizomes, creating an ecotone between marine and terrestrial systems that provides essential ecosystem services (e.g. shoreline protection, nutrient supply to adjacent dune systems). However, little is still known about the diversity of macrofauna that lives in this wrack and how its community structure varies in space and time. In this study, we assessed the variation in macrofauna composition on three Mallorcan beaches (Balearic Islands, Western Mediterranean Sea) characterized by different geomorphological features. For an entire year, we seasonally sampled P. oceanica wrack on each beach and identified the animal species living in them. We found up to 20 different species belonging to four functional groups: (A) detritivores/fungivores/scavengers, (B) phytophagous, (C) secondary consumers, and (D) tertiary consumers. Species composition and diversity indices showed strong differences among beaches associated with wrack dynamism. Both variables revealed also a significant temporal variation, with highest individual abundance in summer and lowest in winter. Detritivores were the most abundant group, and their contribution to community structure represented over 75% through the study period. Springtails, in particular, contributed the most (45%) to spatial and temporal changes in community structure, followed by the oligochaete Enchytraeus sp. (12.6%) and the sand hopper Talitrus saltator (4.6%). Our study builds towards a more robust understanding of these marine-terrestrial ecotones, demonstrating the existence of complex and dynamic macrofauna communities which can provide more ecological information about the food webs of these ecosystems and the services they provide., This work was funded by the Spanish Ministry of Economy and Competitiveness (MedShift, CGL2015-71809-P) and the Government of the Balearic Islands (Competitive Group of Excellence GAEM). MAJ acknowledges financial support from the JAE-Doc program (CSIC, co-funded by FSE). We are very grateful to “Finca Pública de Son Real” staff for letting us work in their area and providing logistic support. We also thank Clara Vignolo for help both in the field and lab. Different taxonomists kindly aided us with the identification of the taxa: Lluc García (Isopoda), Xavier Canyelles (Coleoptera), and Dr. Antonio García- Valdecasas and Dr. Ilse Bartsch (Acari). The study is framed within project CGL-2017-88122-P financed by the Spanish Ministry of Science and Innovation, Spain.

Oceanic island ecosystems favour the appearance of novel interactions as a consequence of their depauperate and disharmonic flora and fauna. We investigated Echium simplex, endemic to the Anaga Biosphere Reserve in NE Tenerife, Canary Islands, belongs to the Canarian bird–flower element. Along two flowering seasons, we studied the breeding system of E. simplex, identified the floral visitors and compared the pollination effectiveness of different animal guilds (insects versus vertebrates) by means of selective exclosures. E. simplex is self-compatible but selfing significantly reduced fruit set. The flowers were visited by five bird species (mostly Phylloscopus canariensis and Serinus canarius, but also Cyanistes teneriffae, Sylvia atricapilla and Sylvia melanocephala), a lizard species (Gallotia galloti) and over a hundred insect species (mainly hymenopterans and coleopterans). Flying insects increased fruit set whereas small flower dwellers (mostly beetles) decreased both fruit and seed set. Vertebrates had a negligible effect on reproductive success. We conclude that although the floral resources provided by E. simplex may be important to some vertebrate species, these do not appear to contribute to increase fitness of the plant, which was more dependent upon flying insects for fruit and seed set. We additionally found that plant reproductive structures are heavily damaged by feral goats, which threaten the maintenance of this Canarian endemic species., The study was funded by a predoctoral fellowship to Julia Jaca from the Ministerio de Educación, Cultura y Deporte [FPU13/05880] and framed within a project financed by Ministerio de Economía, Industria y Competitividad [CGL2013‐44386‐P] to Anna Traveset.

An increasing number of double mutualisms (i.e. two interacting species benefiting each other in two different functions, e.g. pollination and seed dispersal) have been reported, mainly from island ecosystems, although we still lack much information on how effective such species are in both processes. Here, we assessed the pollination effectiveness of a double mutualism between an ancient Mediterranean gymnosperm, Ephedra fragilis, and a lizard, Podarcis lilfordi. On the one hand, we assessed the lizard contribution to different fitness measures (seed set and germination success), relative to that of insects and the wind effect; on the other, we determined the lizards’ seed removal rate (i.e. the quantity component of seed dispersal effectiveness). In both processes, we further tested for differences in their contributions among male, female and juvenile lizards. Ephedra fragilis showed to be mostly anemophilous, lizards and insects playing only a minor role on seed set. However, lizards qualitatively contributed to pollination success, as seeds coming from lizard-pollinated cones germinated at higher rates than those pollinated by wind or insects, although this was detected only for small seeds (, Our study provides evidence that the relationship between the Balearic endemic lizard Podarcis lilfordi and the plant Ephedra fragilis constitutes one of the five pollination/seed dispersal double mutualisms found around the World between an animal and a gymnosperm, besides representing the first double mutualism reported in the Mediterranean region. Although P. lilfordi does not contribute substantially to the pollination of E. fragilis, it does play a crucial role in the dispersal process. In turn, by means of the pollination drops and the fleshy cone scales, the plants feed its only seed disperser in this islet.

The disappearance of native seed dispersers due to anthropogenic activities is often accompanied by the introduction of alien species, which may to some extent replace the ecological service provided by the extinct ones. Yet, little empirical evidence exists demonstrating the evolutionary consequences of such alien “replacement.” Here, we document the conflicting selection exerted on seed size by two native lizards (Podarcis lilfordi and P. pityusensis) and an alien mammal species (Martes martes), all acting as legitimate seed dispersers of the Mediterranean relict Cneorum tricoccon. While lizards mostly exerted a negative directional selection on seed diameter, especially P. pityusensis, the much larger pine marten exerted positive selection on seed size. Our findings suggest that this among-disperser variation in the selection regimes, together with the occurrence of spatial variation in the presence of each seed disperser, help to create the geographical variation observed for seed size of C. tricoccon. To our knowledge, this is the first empirical evidence showing opposing selective pressures between native and alien species in the seed dispersal process in an invaded ecosystem., This study is framed within several projects funded by the Spanish Government (CGL2017‐88122‐P to AT, and CGL2L013‐47429‐P to AV). GEA was supported by Juan de la Cierva Programme.

Fern sporangia may provide an important source of energy for bird species, which in turn can act as potential dispersers of viable spores. This study reports the first case of fern spore dispersal by land birds. We document the consumption of fern sporangia and evaluate the potential spore dispersal by Galápagos finches on Santa Cruz Island. Overall, 18% of the 34 sampled individuals of three finch species, the Vegetarian Finch (Platyspiza crassirostris), the Small Ground Finch (Geospiza fuliginosa) and the Medium Ground Finch (Geospiza fortis), were found to disperse viable spores of two native ferns, Asplenium auritum and Asplenium feei., This research was undertaken within project CGL2017-88122-P funded by the Ministerio de Economía y Competitividad, Spain.

[Premise of the Study] The characteristic scarcity of insects on remote oceanic islands has driven nonflower-specialized vertebrates to broaden their trophic niches and explore floral resources. From our previous studies in the Galápagos, we know that native insectivorous and frugivorous birds visit a wide range of entomophilous flowers and can also act as effective pollinators. Here, we tested whether opportunistic Galápagos birds show any preference for specific floral traits, and if so, this preference differs from that of insects, [Methods] Sixteen floral morphology and nectar traits of 26 native species were studied, as well as the frequency with which they are visited by birds and insects. Nonmetric multidimensional scaling (NMDS) was used to evaluate the distribution of flower traits values along two main dimensions and measure the similarity between the plants visited mostly by birds versus those by insects, [Key Results] NMDS of floral traits resulted in two species groups: (1) bell-shaped, white flowers with wider corollas at nectary level and higher nectar volume, associated with high bird visitation rates; and (2) bowl and tubular-shaped flowers with narrower corollas at nectary level and lower nectar volume, associated with high insect visitation rates, [Conclusions] Despite the divergence in floral trait preferences between opportunistic Galápagos birds and insects, bird-visited flowers display mixed traits not fitting the classical ornithophilous syndrome. This finding is compatible with the existence of a transitional or bet-hedging phenotype between insect and bird visitors and underscores the importance of coevolution and floral diversification in nonspecialized plant–visitor interactions., This research is framed within projects CGL2013-44386-P, CGL2015-67865-P, and CGL2017-88122-P funded by the Ministerio de Economía y Competitividad (MINECO), Spain.

Many invasive plant species have fleshy fruits that are eaten by native frugivorous birds which disperse their seeds and may facilitate their germination, playing an important role in plant invasion success. The fleshy-fruited shrub Cotoneaster franchetii (Rosaceae) is an important invasive alien in the mountainous regions of central Argentina. To determine the role of avian frugivorous in fruit removal of this species, we conducted a frugivore exclusion experiment including bagged and unbagged branches in 75 plants of C. franchetii. At the end of the dispersal period, we compared the percentage of missing fruits (removed by birds + naturally dropped) in unbagged branches with the percentage of naturally dropped fruits in bagged branches. To assess whether any mechanism acting on seeds during their passage through bird guts (de-inhibition by pulp removal and/or seed scarification) affects seed germination of this species, we compared percentage and speed of germination among seeds obtained from faeces of the native frugivorous Turdus chiguanco, from manually de-pulped fruits, and from intact fruits. The percentage of missing fruits per shrub in unbagged branches was significantly higher than the percentage of naturally dropped fruits in bagged branches, suggesting that frugivorous birds play an important role in fruit removal of C. franchetii in the study area. Seeds from bird faeces and from manually de-pulped fruits germinated in higher percentage and faster than seeds from intact fruits. Germination percentage and speed of seeds from manually de-pulped fruits were significantly higher than those of gut-passed seeds. These results indicate that T. chiguanco increases and accelerates seed germination of C. franchetii through pulp removal, but not through seed scarification. Overall, our findings indicate that native frugivorous birds facilitate the dispersal and germination success of C. franchetii, likely playing an important role in its invasion throughout the mountainous region of central Argentina. Fil: Diaz Velez, Maria Celeste. 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: Sersic, Alicia Noemi. 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: Traveset, Anna. Consejo Superior de Investigaciones Cientificas. Instituto Mediterraneo de Estudios Avanzados; España Fil: Paiaro, Valeria. 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

Alien invasive plant species can affect pollination, reproductive success and population dynamics of co-flowering native species via shared pollinators. Consequences may range from reproductive competition to facilitation, but the ecological drivers determining the type and magnitude of such indirect interactions remain poorly understood. Here, we examine the role of the spatial scale of invader presence and spatially contingent behavioural responses of different pollinator groups as potential key drivers, using the invasive Oxalis pes-caprae and the self-incompatible native annual Diplotaxis erucoides as a model system. Three treatments were assigned to native focal plants: (1) invader present at the landscape scale (hectares) but experimentally removed at the floral neighbourhood scale (pa); (2) invader present at both scales (pp); (3) invader absent at both scales (aa). Interestingly, we found pronounced spatially contingent differences in the responses of pollinators: honeybees and bumblebees were strongly attracted into invaded sites at the landscape scale, translating into native plant visitation facilitation through honeybees, while bumblebees almost exclusively visited Oxalis. Non-corbiculate wild bees, in contrast, showed less pronounced responses in foraging behavior, primarily at the floral neighborhood scale. Average heterospecific (Oxalis) pollen deposition onto stigmas of Diplotaxis was low (, This work was supported by a fellowship for prospective researchers by the Swiss National Science Foundation (Grant No. PBZHP3-131020).

Aim Although biological invasions represent a major cause of biodiversity loss, the actual mechanisms driving species extinctions remain insufficiently understood. Here we investigate the role of three processes as drivers of phylogenetic loss in invaded local plant communities, namely the ‘biotic resistance’, ‘environmental filtering’ and ‘functional equivalence’ hypotheses. Location Balearic Islands (western Mediterranean). Methods We quantified the phylogenetic diversity and structure of 109 pairs of invaded and non-invaded local plant communities from two Mediterranean islands. Each pair contained one control plot and one plot invaded either by the deciduous tree Ailanthus altissima, the succulent subshrubs Carpobrotus spp. or the pseudoannual geophyte Oxalis pes-caprae. We combined generalized linear models, analyses of phylogenetic community structure and generalized linear mixed models using a Markov chain Monte Carlo technique (MCMCglmm) to contrast the ‘biotic resistance’, ‘environmental filtering’ and ‘functional equivalence’ hypotheses. Results While the phylogenetic structure of the non-invaded communities was not more clustered or overdispersed than expected by chance, minimum phylogenetic distance to the invasive species increased in invaded assemblages, in which the magnitude of phylogenetic diversity loss ranged from 6 to 37% depending on the invader’s identity. Invader or island identity did not explain the probabilities of native species becoming locally extinct. Rather, the likelihood of extinction was mainly explained by species abundance, with scarcer species exhibiting a higher chance of becoming locally extinct. Species identity explained a small fraction of the variation in extinction risk (12%), independently of each species’ evolutionary history. Main conclusions The most relevant driver of local extinction is a stochastic process where less abundant species tend to disappear more frequently irrespective of their evolutionary history. This has strong implications for conservation because it suggests that in the study region the invaders are unlikely to drive regional and global extinctions except in cases where the native species is already rare.

AimAlien species alter interaction networks by disrupting existing interactions, for example between plants and pollinators, and by engaging in new interactions. Predicting the effects of an incoming invader can be difficult, although recent work suggests species roles in interaction networks may be conserved across locations. We test whether species roles in plant–pollinator networks differ between their native and alien ranges and whether the former can be used to predict the latter.LocationWorld-wide.MethodsWe used 64 plant–pollinator networks to search for species occurring in at least one network in its native range and one network in its alien range. We found 17 species meeting these criteria, distributed in 48 plant–pollinator networks. We characterized each species’ role by estimating species-level network indices: normalized degree, closeness centrality, betweenness centrality and two measures of contribution to modularity (c- and z-scores). Linear mixed models and linear regression models were used to test for differences in species role between native and alien ranges and to predict those roles from the native to the alien range, respectively.ResultsSpecies roles varied considerably across species. Nevertheless, although species lost their native mutualists and gained novel interactions in the alien community, their role did not differ significantly between ranges. Consequently, closeness centrality and normalized degree in the alien range were highly predictable from the native range networks.Main conclusionsSpecies with high degree and centrality define the core of nested networks. Our results suggest that core species are likely to establish interactions and be core species in the alien range, whilst species with few interactions in their native range will behave similarly in their alien range. Our results provide new insights into species role conservatism and could help ecologists to predict alien species impact at the community level.

[Background and Aims] Alpine oceanic ecosystems are considered amongst the most ephemeral and restricted habitats, with a biota highly vulnerable to climate changes and disturbances. As an example of an alpine insular endemic, the past and future population genetic structure and diversity, and the future distribution of Viola cheiranthifolia (Violaceae), endemic to Tenerife (Canary Islands), were estimated. The main goals were to predict distribution changes of this alpine oceanic plant under climate change, and to assist in actions for its conservation., [Methods] To perform population genetic analysis, 14 specific microsatellite markers and algorithms which considered the polyploid condition of V. cheiranthifolia were employed. The niche modelling approach incorporated temperature gradients, topography and snow cover maps. Models were projected into climate change scenarios to assess the extent of the altitudinal shifts of environmental suitability. Finally, simulations were performed to predict whether the environmental suitability loss will affect the genetic diversity of populations., [Key Results] Viola cheiranthifolia presents short dispersal capacity, moderate levels of genetic diversity and a clear population genetic structure divided into two main groups (Teide and Las Cañadas Wall), showing signs of recolonization dynamics after volcanic eruptions. Future estimates of the distribution of the study populations also showed that, despite being extremely vulnerable to climate change, the species will not lose all its potential area in the next decades. The simulations to estimate genetic diversity loss show that it is correlated to suitability loss, especially in Las Cañadas Wall., [Conclusions] The low dispersal capacity of V. cheiranthifolia, coupled with herbivory pressure, mainly from rabbits, will make its adaptation to future climate conditions in this fragile alpine ecosystem difficult. Conservation actions should be focused on herbivore control, population reinforcement and surveillance of niche shifts, especially in Guajara, which represents the oldest isolated population and a genetic reservoir for the species., We thank the staff from the Teide National Park for the permissions granted and all the help during the fieldwork. This work was supported by Organismo Autónomo de Parques Nacionales, Ministerio de Agricultura y Pesca, Alimentación y Medio Ambiente [grant no. 255/2011] and Agencia Canaria de Investigación, Innovación y Sociedad de la Información, Gobierno de Canarias [grant no. TESIS20120004

Life on oceanic islands deviate in many ways from that on the mainland. Their biodiversity is relatively poor and some groups are well-represented, others not, especially not insects. A scarcity of insects forces birds to explore alternative food, such as nectar and fruit. In this way, island birds may pollinate and disperse seed to an extent unseen on any mainland; they may even first consume floral resources of a plant species and then later harvest the fruit of the same species. Through this biotic reuse, they may act as double mutualists. The latter have never been studied at the level of the network, because they are traditionally considered rare. We sampled pollination and seed-dispersal interactions on Galápagos and constructed a plant-bird mutualism network of 108 plant (12% being double mutualists) and 21 bird species (48% being double mutualists), and their 479 interactions, being either single (95%) or double mutualisms (5%). Double mutualists constitute the core in the pollination-dispersal network, coupling the two link types together. They may also initiate positive feedbacks (more pollination leading to more dispersal), which theoretically are known to be unstable. Thus, double mutualisms may be a necessary, but risky prerequisite to the survival of island biodiversity., We thank the BBVA Foundation and The Danish National Science Research Council for funding.

Island biogeography theory is one of the most influential paradigms in ecology. That island characteristics, including remoteness, can profoundly modulate biological diversity has been borne out by studies of animals and plants. By contrast, the processes influencing microbial diversity in island systems remain largely undetermined. We sequenced arbuscular mycorrhizal (AM) fungal DNA from plant roots collected on 13 islands worldwide and compared AM fungal diversity on islands with existing data from mainland sites. AM fungal communities on islands (even those >6000 km from the closest mainland) comprised few endemic taxa and were as diverse as mainland communities. Thus, in contrast to patterns recorded among macro-organisms, efficient dispersal appears to outweigh the effects of taxogenesis and extinction in regulating AM fungal diversity on islands. Nonetheless, AM fungal communities on more distant islands comprised a higher proportion of previously cultured and large-spored taxa, indicating that dispersal may be human-mediated or require tolerance of significant environmental stress, such as exposure to sunlight or high salinity. The processes driving large-scale patterns of microbial diversity are a key consideration for attempts to conserve and restore functioning ecosystems in this era of rapid global change.