1. There is growing interest in understanding the functional outcomes of species
interactions in ecological networks. For many mutualistic networks, including pollination
and seed dispersal networks, interactions are generally sampled by recording
animal foraging visits to plants. However, these visits may not reflect
actual pollination or seed dispersal events, despite these typically being the ecological
processes of interest.
2. Frugivorous animals can act as seed dispersers, by swallowing entire fruits and
dispersing their seeds, or as pulp peckers or seed predators, by pecking fruits to
consume pieces of pulp or seeds. These processes have opposing consequences
for plant reproductive success. Therefore, equating visitation with seed dispersal
could lead to biased inferences about the ecology, evolution and conservation of
seed dispersal mutualisms.
3. Here, we use natural history information on the functional outcomes of pairwise
bird–plant interactions to examine changes in the structure of seven European
plant–frugivore visitation networks after non-mutualistic interactions (pulp pecking
and seed predation) have been removed. Following existing knowledge of the
contrasting structures of mutualistic and antagonistic networks, we hypothesized
a number of changes following interaction removal, such as increased nestedness
and lower specialization.
4. Non-mutualistic interactions with pulp peckers and seed predators occurred in all
seven networks, accounting for 21%–48% of all interactions and 6%–24% of total
interaction frequency. When non-mutualistic interactions were removed, there
were significant increases in network-level metrics such as connectance and nestedness,
while robustness decreased. These changes were generally small, homogenous
and driven by decreases in network size. Conversely, changes in species-level metrics were more variable and sometimes large, with significant decreases in
plant degree, interaction frequency, specialization and resilience to animal extinctions
and significant increases in frugivore species strength.
5. Visitation data can overestimate the actual frequency of seed dispersal services in
plant–frugivore networks. We show here that incorporating natural history information
on the functions of species interactions can bring us closer to understanding
the processes and functions operating in ecological communities. Our categorical
approach lays the foundation for future work quantifying functional interaction outcomes
along a mutualism–antagonism continuum, as documented in other frugivore
faunas., Peer reviewed

Juvenile animals generally disperse from their birthplace to their future breeding territories. In fragmented landscapes, habitat-specialist species must disperse through the anthropogenic matrix where remnant habitats are embedded. Here, we test the hypothesis that dispersing juvenile frugivores leave a footprint in the form of seed deposition through the matrix of fragmented landscapes. We focused on the Sardinian warbler ( Sylvia melanocephala), a resident frugivorous passerine. We used data from field sampling of bird-dispersed seeds in the forest and matrix of a fragmented landscape, subsequent disperser identification through DNA-barcoding analysis, and data from a national bird-ringing programme. Seed dispersal by Sardinian warblers was confined to the forest most of the year, but warblers contributed a peak of seed-dispersal events in the matrix between July and October, mainly attributable to dispersing juveniles. Our study uniquely connects animal and plant dispersal, demonstrating that juveniles of habitat-specialist frugivores can provide mobile-link functions transiently, but in a seasonally predictable way., Spanish MINECO (CGL2017-82847-P) and Junta de Andalucía Excellence Projects (RNM–5731) awarded to P.J., Severo Ochoa Award for Centres of Excellence in R + D + I (SEV-2012-0262) and a postdoctoral fellowship from the Severo Ochoa Program awarded to J.P.G.-V. (SEV-2012-0262). While writing this paper, J.P.G.-V. was funded by a Spanish ‘Ramon y Cajal’ fellowship (RYC-2017-22095).

ABSTRACT
Synzoochory is the dispersal of seeds by seed-caching animals. The animal partner in this interaction plays a dual role, acting both as seed disperser and seed predator. We propose that this duality gives to synzoochory two distinctive features that have crucial ecological and evolutionary consequences. First, because plants attract animals that have not only positive (seed dispersal) but also negative (seed predation) impacts on their fitness, the evolution of adaptations to synzoochory is strongly constrained. Consequently, it is not easy to identify traits that define a synzoochorous dispersal syndrome. The absence of clear adaptations entails the extra difficulty of identifying synzoochorous plants by relying on dispersal traits, limiting our ability to explore the full geographic, taxonomic and phylogenetic extent of synzoochory. Second, the positive and negative outcomes of interactions with synzoochorous animals are expressed simultaneously. Consequently, synzoochorous interactions are not exclusively mutualistic or antagonistic, but are located at some point along a mutualism-antagonism continuum. What makes synzoochory interesting and unique is that the position of each partner along the continuum can be evaluated for every plant—animal interaction, and thus the continuum can be precisely described by assessing the relative frequency of positive and negative interaction events in each pairwise interaction. Herein we explore these two main features of synzoochory with a comprehensive quantitative survey of published studies on synzoochory. Synzoochory has been recorded for at least 1339 plant species differing in life forms, from annual and short-lived herbs to long-lived trees, belonging to 641 genera and 157 families widely distributed across the globe and across the seed plant phylogeny. Over 30 animal families belonging to five disparate taxonomic groups (rodents, marsupials, birds, insects, and land crabs) potentially act as synzoochorous dispersers. Although synzoochory appears to be fundamentally a secondary dispersal mode, many abundant and dominant trees are primarily synzoochorous. In addition, we found evidence of the existence of diplosynzoochory (caching animals acting both as primary and secondary dispersers of the same individual seed), mostly in nut-bearing trees. Finally, we found that synzoochorous interactions are widely spread across the mutualism—antagonism continuum. Nevertheless, there were some differences among disperser species and functional groups. Corvids and some rodents (cricetids, nesomyids, sciurids) were located in the positive-effects region of the continuum and presumably behave mostly as dispersers, whereas land crabs and insects were located in the negative-effects extreme and behave mostly as seed predators. Our review demonstrates that synzoochory is not an anecdotal ecological interaction. Rather, it is pivotal to the functioning of many ecosystems where the natural regeneration of keystone plant species depends on the activity of granivorous animals that play a dual role. This distinctive interaction should not be ignored if we wish to have an accurate understanding of the functioning of natural systems., J.M.G. and P.J. were supported by CYTED program (Red Temática 418RT0555). E.W.S. is supported by the Ecology Center and the Utah Agricultural Experiment Station (UAES), Utah State University. P.J. is supported by grant CGL2017‐82847‐P from the Spanish Ministry of Science, Innovation, and Universities (AEI).

The partition of the ecological niche can enhance the coexistence of predators
due to differences in how they exploit three main resources: food, space, and
time, the latter being an axis that often remains unexplored.
2. We studied niche segregation in a Mediterranean mesocarnivore community
composed by Vulpes vulpes, Genetta genetta, Meles meles, and Herpestes ichneumon,
addressing simultaneously different niche axes: the temporal, trophic, and
spatial axes.
3. We assessed temporal segregation between mesopredators and prey and between
potential competitors, using camera trap data between 2018 and 2020 in
a Mediterranean landscape in Southern Spain. We deployed camera traps in 35
stations in three sites with varying vegetation cover within Doñana National Park.
We further examined the spatial overlap in activity centers and trophic preferences
between potential competitors using diet information from studies performed
in the study area.
4. We found an overall temporal segregation between trophic generalist species,
with species showing higher temporal overlap differing in their trophic preferences
and/or showing limited spatial overlap. Furthermore, we observed an overall
high overlap between the activity patterns of predators and their major prey
in the area (the common genet vs. small mammals and the red fox vs. European
rabbit).
5. Our study suggests that coexistence of the different species that compose the
mesocarnivore assemblage in Mediterranean landscapes can be facilitated by subtle
differences along the three main niche axes, with temporal segregation being
a most pronounced mechanism. Our findings reinforce the idea that the coexistence
mechanisms underlying community structure are multidimensional, Peer reviewed

Special Issue: Fruits, animals and seed dispersal: timely advances on a key mutualism., Seed dispersal by frugivorous bird species involves a fine temporal tuning between fruiting plants and birds. However, this interaction may be severely threatened by anthropogenic climate and land-use change, which may result in phenological mismatches and pervasive ecological consequences for avian communities. In this study, we evaluate changes at long (~40 years) and short-time (seasonal) spans in an avian frugivore community using a snapshot resampling. Particularly, we focus on changes in composition, abundance, migratory timing (i.e. phenology) and physical condition in relation to variations in fruit supply. We used bird and fruit data collected during 1981–1983 and 2019–2021 in a Mediterranean scrubland site in Doñana Natural Area, SW Spain. Our findings indicate a profound transformation of species composition, bird phenology and body condition: in ~40 years, the avian community showed a 66% and 18.4% decrease of the abundance of wintering and seed-disperser species, respectively. Seasonal abundance peaks were advanced for at least one month in the 9 out of 11 frugivorous bird species included in the analyses. Avian body condition during the migratory passage has worsened, with fewer individuals showing a high-fat percentage now than in the past. Finally, we report a fruit production decrease of almost half in 2019–2021 compared to 1981–1983, probably linked to habitat encroachment by pine trees and replacement of fleshy-fruited shrubs. Vegetation encroachment and climate change are the most plausible explanations for the observed changes in the avian community, but the relative importance of these factors is yet unknown. Our results at a local scale mirror the dramatic consequences of global change affecting the diversity, phenology and physical condition of frugivorous bird species reported in multiple studies across the globe. The loss of frugivores may trigger feedback mechanisms in which seed dispersal is disrupted, leading to impaired recruitment of fruiting plants and hence less food availability for the avian community., This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 798269 and partially funded from the project CGL 2017-82847 from the Spanish Ministry of Science and Innovation (PJ) and the project BiodivINTERACTOME (P18-HO-4814) from the Junta de Andalucia. AB-L was funded by a Juan de la Cierva-Incorporación grant (IJCI-2017-31419) from the Spanish Ministry of Science and Innovation., Peer reviewed

Ecological interactions are one of the main forces that sustain Earth’s biodiversity. A major challenge for studies of ecology and evolution is to determine how these interactions affect the fitness of species when we expand from studying isolated, pairwise interactions to include networks of interacting species1,2,3,4. In networks, chains of effects caused by a range of species have an indirect effect on other species they do not interact with directly, potentially affecting the fitness outcomes of a variety of ecological interactions (such as mutualism)5,6,7. Here we apply analytical techniques and numerical simulations to 186 empirical mutualistic networks and show how both direct and indirect effects alter the fitness of species coevolving in these networks. Although the fitness of species usually increased with the number of mutualistic partners, most of the fitness variation across species was driven by indirect effects. We found that these indirect effects prevent coevolving species from adapting to their mutualistic partners and to other sources of selection pressure in the environment, thereby decreasing their fitness. Such decreases are distributed in a predictable way within networks: peripheral species receive more indirect effects and experience higher reductions in fitness than central species. This topological effect was also evident when we analysed an empirical study of an invasion of pollination networks by honeybees. As honeybees became integrated as a central species within networks, they increased the contribution of indirect effects on several other species, reducing their fitness. Our study shows how and why indirect effects can govern the adaptive landscape of species-rich mutualistic assemblages., This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES), finance code 001. L.G.C. is funded by a São Paulo Research Foundation PhD scholarship (FAPESP; grants 2019/22146-3 and 2022/07939-0). P.R.G. is funded by Brazil’s Council for Scientific and Technological Development (CNPq; grant 307134/2017-2), FAPESP (grant 2018/14809-0) and the Royal Society (CHL/R1/180156). A.P.A.A. was supported by CAPES, finance code 001, and FAPESP (grant 2016/14277-2). M.M.P. is funded by FAPESP (grant 2019/25478-7) and CNPq (grant 313059/2022-5). M.A.M.A. is funded by FAPESP (grant 2021/14335-0-ICTP‐SAIFR), and by CNPq (grant 301082/2019‐7). A.V. is supported by the Spanish Ministry of Science, Innovation, and Universities (PGC2018-099772-B-100). P.J. is funded by the Spanish Ministry of Science, Innovation, and Universities (CGL2017-82847-P), LifeWatch ERIC-SUMHAL (LIFEWATCH-2019-09-CSIC-13)/FEDER-EU funding), and the VI and VII Research Funding Program from the Universidad de Sevilla (2021/00000826). J.B. is supported by the Swiss National Science Foundation (grant 310030_197201). We thank R. Cogni, M. A. R. Mello, C. R. Montoya and M. C. Vidal for comments on previous versions of this manuscript., Peer reviewed

Special Issue:Fruits, animals and seed dispersal: timely advances on a key mutualism., Recording species interactions is one of the main challenges in ecological studies. Frugivory has received much attention for decades as a model for mutualisms among free-living species, and a variety of methods have been designed and developed for sampling and monitoring plant–frugivore interactions. The diversity of techniques poses an important challenge when comparing, combining or replicating results from different sources with different methodologies. With the emergence of modern techniques, such as molecular analysis or multimedia remote recorders, issues when combining data from different sources have become especially relevant. We provide an overview of all the techniques used for monitoring endozoochorous primary seed dispersal, focusing on a critical appraisal of the advantages and limitations, as well as the context-dependency nature, of the different methods. We propose five data merging approaches potentially useful to combine frugivory interactions data from different methodologies. Additionally, we provide two case studies where we combine empirical data from plant–animal interactions in Mediterranean shrublands using different methodologies. Data merging resulted in a net increase in the number of distinct pairwise interactions recorded and compensated biases inherent to different methods, resulting in a more robust estimation of network topological descriptors. These case studies clarify the context-dependent character of the merging approaches, highlighting the value of collecting detailed information on the sampling effort in terms of reliable results and reproducibility. Finally, we discuss the trends with different methodological approaches used in the last decades and future perspectives in this field., Our work was funded by project by CGL2017-82847-P from the Agencia Estatal de Investigación, Spain. During their respective PhD projects, EQ is being supported by ‘La Caixa' Foundation grant ID LCF/BQ/DE18/11670007, and JI by FPI grant PRE2018-085916 from the Spanish Ministry of Science and Innovation., Peer reviewed

Indirect interactions among species within ecological communities govern ecological and evolutionary processes as much as, or even more, than direct effects. In insect-pollinated plant communities, indirect interactions between plants can be mediated by shared pollinators, and may influence plant fitness, population growth and community structure. As individuals are the entities actually interacting in nature, rather than species, downscaling a hierarchical level (i.e. from species to individuals) is essential to understand the underlying processes promoting these indirect interactions. We combined empirical data on plant–pollinator interactions collected in Mediterranean shrublands with a novel modelling framework to assess how the patterns of heterospecific and conspecific pollinator sharing between plant individuals are generated and their fitness implications. We found that the effects of flowering synchrony on pollinator sharing among conspecific and heterospecific plant individuals outperformed those of spatial distance. Our results revealed that plant individuals that shared more pollinators with conspecifics were also involved in a higher pollinator sharing with heterospecifics. For most plant species, the sharing of pollinator species between heterospecific plant individuals produced positive mean fitness outcomes, as long as plants did not share many pollinator interactions, which had negative effects on their fitness. At the level of plant individuals, we found that specific combinations of conspecific and heterospecific pollinator sharing lead to distinct reproductive outcomes that placed each individual along a competition–facilitation continuum. Interestingly, most plant species included a higher proportion of individuals likely experiencing competition compared to those potentially involved in facilitation processes. Our contribution provides novel insights into the factors responsible for local-scale indirect interactions within communities and their individual-level functional consequences. Such intricate patterns of indirect interactions have far-reaching implications, as the transitions of plant individuals along competitive or facilitative processes mediated by shared mutualists may contribute significantly to the functioning and coexistence of ecological communities., BA-C received funding from the Ministry of Universities of the Spanish Government (Ref. FPU19_02552). BA-C and PJ were supported by grants CGL2017-82847-P and PID2022-136812NB-I00, funded by MCIN/AEI/10.13039/501100011033 and by the “European Union NextGenerationEU/PRTR”, grant P20_00736 from Junta de Andalucía, and a LifeWatch ERIC-SUMHAL project (LIFEWATCH-2019-09-CSIC-13), with FEDER-EU funding., Peer reviewed

Ecologists have long recognized that seed dispersal mutualisms trigger natural regeneration and range expansion of animal-dispersed trees. Yet we lack empirical studies addressing whether frugivore activity influences founder effects, which reduce genetic diversity at the colonization front of expanding populations. Here, we evaluate the contribution, from both demographic and genetic perspectives, of animal frugivores dispersing seeds across an expansion gradient. We used DNA barcoding for frugivores identification and highly polymorphic genetic markers (SSRs) for maternal analysis of juniper seeds to investigate how (1) stand maturity, (2) microhabitat types and (3) foraging patterns shape the distribution of the maternal progenies along this gradient. We expect both reduced seed rain density and low numbers of source trees contributing to the seed rain at the colonization front, with limited availability of local fruiting trees. We also anticipated that large-sized frugivore species would promote maternally rich seed rain due to their ability to mix seed progenies during digestive processing and move further distances across the landscape. Contrary to our expectations, we found that all identified frugivores produced dense and genetically diverse seed rains across the expansion gradient, even at the colonization front, characterized by scarce fruiting trees. Synthesis: Our findings shed light on the fundamental and applied implications of plant–frugivore interactions in shaping highly diverse second-growth forests. These results emphasize the necessity of preserving plant–animal mutualistic interactions to ensure the persistence and expansion of natural tree populations, particularly in formerly fragmented landscapes., Our work was funded by grants CGL2017-82847-P and PID2022-136812NB-I00, Spanish Ministry of Science and Innovation and grant SUMHAL, LIFEWATCH-2019-09-CSIC-13, POPE 2014–2020, MICINN through the European Regional Development Fund, as well as funding from the VI Plan Propio de Investigación of the Universidad de Sevilla (VI PPIT-US) (PJ). JI was supported by an FPI grant PRE2018-085916 from the Spanish Ministry of Science and Innovation. MJF was supported by Investigadores por México-CONAHCYT (grant number: 73215). CG was supported by the Research Application Support Programme (RHUL) and the Royal Society (Research Application Support Programme) RaSP., Peer reviewed