How intraspecific variation in seed-dispersing animals matters for plants

Importance of plant and fruit traits on the structure of bird seed dispersal networks in different disturbed habitats

Species functional traits can influence seed dispersal processes and consequently affect species' role in the mutualistic network. Although the effect of animal traits on the structure of the seed dispersal network is well explored, it remains poorly understood how plant and fruit traits contribute to the structure. We here studied the effects of plant and fruit traits on the structure of bird seed dispersal networks across different disturbed habitats in the Meihua Mountain National Nature Reserve, Southeastern China. During the study period, 16, 20, 13, and 15 bird species were recorded foraging on 10, 11, 12, and 8 plant species, resulting in 511, 312, 265, and 201 foraging events in the protected forest, natural forest, village, and bamboo forest, respectively. The composition of these seed dispersal networks is not primarily influenced by a specific group of bulbul species, but rather by the presence of an endangered plant species, Taxus chinensis. As we expected, the structure of the four networks was different among the four disturbed habitats. Furthermore, our results also showed tree height and canopy density were the most important plant traits for structuring the seed dispersal network, while sugar, amylase, dry matter, and alkaloids were identified as significant fruit traits. Overall, our findings highlight the value of integrating trait-based ecology into the framework of the seed dispersal network and provide new insights for mutualistic network conservation in disturbed habitats.

Pollen analysis reveals the effects of uncovered interactions, pollen-carrying structures, and pollinator sex on the structure of wild bee-plant networks

Pollination networks are increasingly used to model the complexity of interactions between pollinators and flowering plants in communities. Different methods exist to sample these interactions, with direct observations of plant-pollinator contacts in the field being by far the most common. Although the identification of pollen carried by pollinators allows uncovering interactions and increasing sample sizes, the methods used to build pollen-transport networks are variable and their effect on network structure remains unclear. To understand how interaction sampling influences the structure of networks, we analyzed the pollen found on wild bees from eight communities across Mallorca Island and investigated the differences in pollen loads between bee body parts (scopa vs. body) and sexes. We then assessed how these differences, as well as the uncovered interactions not detected in the field, influenced the structure of wild bee-plant networks. We identified a higher quantity and diversity of pollen in the scopa than in the rest of the female body, but these differences did not lead to differences in structure between plant-pollination (excluding scopa pollen) and bee-feeding interaction (including scopa pollen) networks. However, networks built with pollen data were richer in plant species and interactions and showed lower modularity and specialization (H2'), and higher nestedness than visitation networks based on field observations. Female interactions with plants were stronger compared to those of males, although not richer. Accordingly, females were more generalist (low d') and tended to be more central in interaction networks, indicating their more key role structuring pollination networks in comparison to males. Our study highlights the importance of palynological data to increase the resolution of networks, as well as to understand important ecological questions such as the differences between plant-pollination and bee-feeding interaction networks, and the role of sexes in pollination.

Feedback loops drive ecological succession: towards a unified conceptual framework

The core principle shared by most theories and models of succession is that, following a major disturbance, plant-environment feedback dynamics drive a directional change in the plant community. The most commonly studied feedback loops are those in which the regrowth of the plant community causes changes to the abiotic (e.g. soil nutrients) or biotic (e.g. dispersers) environment, which differentially affect species availability or performance. This, in turn, leads to shifts in the species composition of the plant community. However, there are many other PE feedback loops that potentially drive succession, each of which can be considered a model of succession. While plant-environment feedback loops in principle generate predictable successional trajectories, succession is generally observed to be highly variable. Factors contributing to this variability are the stochastic processes involved in feedback dynamics, such as individual mortality and seed dispersal, and extrinsic causes of succession, which are not affected by changes in the plant community but do affect species performance or availability. Both can lead to variation in the identity of dominant species within communities. This, in turn, leads to further contingencies if these species differ in their effect on their environment (priority effects). Predictability and variability are thus intrinsically linked features of ecological succession. We present a new conceptual framework of ecological succession that integrates the propositions discussed above. This framework defines seven general causes: landscape context, disturbance and land-use, biotic factors, abiotic factors, species availability, species performance, and the plant community. When involved in a feedback loop, these general causes drive succession and when not, they are extrinsic causes that create variability in successional trajectories and dynamics. The proposed framework provides a guide for linking these general causes into causal pathways that represent specific models of succession. Our framework represents a systematic approach to identifying the main feedback processes and causes of variation at different successional stages. It can be used for systematic comparisons among study sites and along environmental gradients, to conceptualise studies, and to guide the formulation of research questions and design of field studies. Mapping an extensive field study onto our conceptual framework revealed that the pathways representing the study's empirical outcomes and conceptual model had important differences, underlining the need to move beyond the conceptual models that currently dominate in specific fields and to find ways to examine the importance of and interactions among alternative causal pathways of succession. To further this aim, we argue for integrating long-term studies across environmental and anthropogenic gradients, combined with controlled experiments and dynamic modelling.

Boldness suppresses hoarding behavior in food hoarding season and reduces over-wintering survival in a social rodent

The "pace-of-life" syndrome (POLS) framework can encompass multiple personality axes that drive important functional behaviors (e.g., foraging behavior) and that co-vary with multiple life history traits. Food hoarding is an adaptive behavior important for an animal's ability to adapt to seasonal fluctuations in food availability. However, the empirical evidence for the relationships between animal personality and hoarding behavior remains unclear, including its fitness consequences in the POLS framework. In this study, the Mongolian gerbil (Meriones unguiculatus), a social rodent, was used as a model system to investigate how boldness or shyness is associated with food hoarding strategies during the food hoarding season and their impact on over-winter survival and reproduction at both individual and group levels. The results of this study showed that, compared with shy gerbils, bold gerbils had a lower effort foraging strategy during the food hoarding season and exhibited lower over-winter survival rates. However, bold-shy personality differences had no effect on over-winter reproduction. These findings suggest that the personality is a crucial factor influencing the foraging strategy during the food hoarding season in Mongolian gerbils. Personality may be related to energy states or the reaction to environmental changes (e.g., predation risk and food availability) in bold or shy social animals. These results reflect animal life history trade-offs between current versus future reproduction and reproduction versus self-maintenance, thereby helping Mongolian gerbils in adapting to seasonal fluctuations in their habitat.

Managing wildlife tolerance to humans for ecosystem goods and services

Many animals can vary their behaviors to better utilize anthropogenic environments. Wildlife living in highly disturbed environments often show an increased tolerance towards humans. While animal behavior can play a vital role in producing and delivering ecosystem services, we know less about how variation in wildlife tolerance to humans can influence ecosystem services. Increased tolerance to humans changes a variety of animal behaviors, and these behavioral modifications, such as changes to foraging, habitat selection, and movement, can alter the supply and flow of both ecosystem services and disservices. We highlight the need to understand the links between increased tolerance to humans and ecosystem services to develop an effective tool to enhance services while minimizing the risk of creating disservices.

Density-Dependent Seed Predation of Quercus wutaishanica by Rodents in Response to Different Seed States

The predation and/or dispersal of Quercus seeds by rodents play an important role in the creation of the tree species. The present study examined the effects of community habitats on the predation and dispersal of Quercus wutaishanica seeds by rodents. We released seeds with densities set at 2, 4, 8, 16, and 32 seed square meter with litter cover, soil burial, and bare ground in the Liupan Mountains National Nature Reserve in the Ningxia Hui Autonomous Region, northwest China. The results showed that (1) the litter cover and soil burial significantly increased the seed survival probability compared with bare ground treatments, especially the predation in situ (PIS) (p < 0.05). Both the scatter hoarding (SH) and larder hoarding (LH) for litter cover and soil burial were significantly increased compared with bare ground (p < 0.05). (2) The large seeds are preferentially predated after dispersal and their long-distance dispersal (>5 m) was significantly greater than that of small seeds (p < 0.05), while small seeds are more likely to be preyed on in situ or during short-distance dispersal (<3 m). (3) The Q. wutaishanica seed predation by rodents increased at a high density rather than at a low density, indicating a negative density-dependent predation. These findings provide insights into the ecological characteristics of Quercus tree regeneration and shed light on the coexistence between rodents and different-sized seeds.

The sensory ecology of primate food perception, revisited

Twenty years ago, Dominy and colleagues published "The sensory ecology of primate food perception," an impactful review that brought new perspectives to understanding primate foraging adaptations. Their review synthesized information on primate senses and explored how senses informed feeding behavior. Research on primate sensory ecology has seen explosive growth in the last two decades. Here, we revisit this important topic, focusing on the numerous new discoveries and lines of innovative research. We begin by reviewing each of the five traditionally recognized senses involved in foraging: audition, olfaction, vision, touch, and taste. For each sense, we provide an overview of sensory function and comparative ecology, comment on the state of knowledge at the time of the original review, and highlight advancements and lingering gaps in knowledge. Next, we provide an outline for creative, multidisciplinary, and innovative future research programs that we anticipate will generate exciting new discoveries in the next two decades.

Linking animal migration and ecosystem processes: Data-driven simulation of propagule dispersal by migratory herbivores

Animal migration is a key process underlying active subsidies and species dispersal over long distances, which affects the connectivity and functioning of ecosystems. Despite much research describing patterns of where animals migrate, we still lack a framework for quantifying and predicting how animal migration affects ecosystem processes. In this study, we aim to integrate animal movement behavior and ecosystem functioning by developing a predictive modeling framework that can inform ecosystem management and conservation.

We propose a framework to model individual‐level migration trajectories between populations' seasonal ranges as well as the resulting dispersal and fate of propagules carried by the migratory animals, which can be calibrated using empirical data at every step of the modeling process. As a case study, we applied our framework to model the spread of guava seeds, Psidium guajava, by a population of migratory Galapagos tortoises, Chelonoidis porteri, across Santa Cruz Island. Galapagos tortoises are large herbivores that transport seeds and nutrients across the island, while Guava is one of the most problematic invasive species in the Galapagos archipelago.

Our model can predict the pattern of spread of guava seeds alongside tortoises' downslope migration range, and it identified areas most likely to see establishment success. Our results show that Galapagos tortoises' seed dispersal may particularly contribute to guava range expansion on Santa Cruz Island, due to both long gut retention time and tortoise's long‐distance migration across vegetation zones. In particular, we predict that tortoises are dispersing a significant amount of guava seeds into the Galapagos National Park, which has important consequences for the native flora.

The flexibility and modularity of our framework allow for the integration of multiple data sources. It also allows for a wide range of applications to investigate how migratory animals affect ecosystem processes, including propagule dispersal but also other processes such as nutrient transport across ecosystems. Our framework is also a valuable tool for predicting how animal‐mediated propagule dispersal can be affected by environmental change. These different applications can have important conservation implications for the management of ecosystems that include migratory animals.

Reduced evolutionary potential of a frugivorous bird species in fragmented forests

Morphological attributes are important in determining the success of ecological interactions, such as the interactions between fleshy fruited plants and their seed dispersers. Morphological traits can present high levels of intraspecific variation both within and across populations. Such variation will not only mediate which interactions can be established locally but also the potential for populations to respond to perturbations and selective pressure. Here, we investigated patterns of morphological variation (body weight and beaks’ traits) among different populations of blue manakin (Chiroxiphia caudata), in the highly fragmented Atlantic Forest, Brazil, both in terms of mean trait values – that might mediate interactions locally – and in their habitat-level variation which influences their evolutionary potential. Using metrics of evolutionary potential derived from quantitative genetics theory, we hypothesized that ecological stress would lead to a decline in the overall evolutionary potential in manakin populations. We found that populations differ slightly in their mean morphological attributes, with the exception of a population that occurs in temperate Araucaria forests. Nevertheless, we found a striking difference in the evolutionary potential of populations from different vegetation types. Specifically, populations that occur in ecological stress areas, Araucaria forests, and forest fragments immersed in savanna presented a smaller overall and conditional evolvability, suggesting their lower ability to respond in the direction of selection. This pattern might have important implications for the role of this species as seed disperser, as populations under stress may lack morphological variation (and covariation) that can be important to allow a given population to disperse seeds of multiple types of fruits. Moreover, a smaller evolvability might impact the potential of these populations to persist and perform their ecosystem services in face of environmental changes.

Competitive release during fire succession influences ecological turnover in a small mammal community

Ecologists have long debated the relative importance of biotic interactions versus species-specific habitat preferences in shaping patterns of ecological dominance. In western North America, cycles of fire disturbance are marked by transitions between North American deermice (Peromyscus maniculatus), which predominate after wildfires, and southern red-backed voles (Myodes gapperi), which gradually replace deermice 3-4 years postfire and maintain dominance as forests mature. While this shift has been frequently documented, the processes that mediate this turnover are debated. One possibility is competitive release, which predicts a reduction in vole competition may contribute to niche expansion and population growth in deermice. Alternatively, turnover in both species may be shaped by differences in their preferred habitat and resource base, as predicted by optimum foraging theory. We evaluate these hypotheses using stable isotopes and spatial mark-recapture of deermouse and vole populations sampled prior to and following a fire as part of a longitudinal study in the Greater Yellowstone Ecosystem. Fire disturbance was associated with a 94% decrease in vole abundance but a 102% increase in deermice. Even after accounting for microhabitat, vole and deermouse populations were negatively correlated spatially and temporally (R = -0.45), and competitor abundance was more important prefire than postfire. When vole abundance was high (prefire), vole dietary niche space was seven times broader than that of deermice. Postfire, deermouse dietary niche nearly tripled and was enriched in ¹³ C (i.e., more C₄ plants), while voles occupied a slightly reduced dietary niche (79% of prefire breadth). Our results suggest deermice are experiencing ecological release due to a reduction in vole competition but vole shifts are largely driven by habitat preferences.

Passive directed dispersal of plants by animals

Conceptual gaps and imprecise terms and definitions may obscure the breadth of plant-animal dispersal relationships involved in directed dispersal. The term 'directed' indicates predictable delivery to favourable microsites. However, directed dispersal was initially considered uncommon in diffuse mutualisms (i.e. those involving many species), partly because plants rarely influence post-removal propagule fate without specialized adaptations. This rationale implies that donor plants play an active role in directed dispersal by manipulating vector behaviour after propagule removal. However, even in most classic examples of directed dispersal, participating plants do not influence animal behaviour after propagule removal. Instead, such plants may take advantage of vector attraction to favourable plant microsites, indicating a need to expand upon current interpretations of directed dispersal. We contend that directed dispersal can emerge whenever propagules are disproportionately delivered to favourable microsites as a result of predictably skewed vector behaviour. Thus, we propose distinguishing active and passive forms of directed dispersal. In active directed dispersal, the donor plant achieves disproportionate arrival to favourable microsites by influencing vector behaviour after propagule removal. By contrast, passive directed dispersal occurs when the donor plant takes advantage of vector behaviour to arrive at favourable microsites. Whereas predictable post-removal vector behaviour is dictated by characteristics of the donor plant in active directed dispersal, characteristics of the destination dictate predictable post-removal vector behaviour in passive directed dispersal. Importantly, this passive form of directed dispersal may emerge in more plant-animal dispersal relationships because specialized adaptations in donor plants that influence post-removal vector behaviour are not required. We explore the occurrence and consequences of passive directed dispersal using the unifying generalized gravity model of dispersal. This model successfully describes vectored dispersal by incorporating the influence of the environment (i.e. attractiveness of microsites) on vector movement. When applying gravity models to dispersal, the three components of Newton's gravity equation (i.e. gravitational force, object mass, and distance between centres of mass) become analogous to propagules moving towards a location based on characteristics of the donor plant, the destination, and relocation processes. The generalized gravity model predicts passive directed dispersal in plant-animal dispersal relationships when (i) animal vectors are predictably attracted to specific destinations, (ii) animal vectors disproportionately disperse propagules to those destinations, and (iii) those destinations are also favourable microsites for the dispersed plants. Our literature search produced evidence for these three conditions broadly, and we identified 13 distinct scenarios where passive directed dispersal likely occurs because vector behaviour is predictably skewed towards favourable microsites. We discuss the wide applicability of passive directed dispersal to plant-animal mutualisms and provide new insights into the vulnerability of those mutualisms to global change.

Small mammal personalities generate context dependence in the seed dispersal mutualism

Mutualisms are foundational components of ecosystems with the capacity to generate biodiversity through adaptation and coevolution and give rise to essential services such as pollination and seed dispersal. To understand how mutualistic interactions shape communities and ecosystems, we must identify the mechanisms that underlie their functioning. One mechanism that may drive mutualisms to vary in space and time is the unique behavioral types, or personalities, of the individuals involved. Here, our goal was to examine interindividual variation in the seed dispersal mutualism and identify the role that different personalities play. In a field experiment, we observed individual deer mice (Peromyscus maniculatus) with known personality traits predating and dispersing seeds in a natural environment and classified all observed interactions made by individuals as either positive or negative. We then scored mice on a continuum from antagonistic to mutualistic and found that within a population of scatter hoarders, some individuals are more mutualistic than others and that one factor driving this distinction is animal personality. Through this empirical work, we provide a conceptual advancement to the study of mutualism by integrating it with the study of intraspecific behavioral variation. These findings indicate that animal personality is a previously overlooked mechanism generating context dependence in plant–animal interactions and suggest that behavioral diversity may have important consequences for the functioning of mutualisms.

Body-size dependent foraging strategies in the Christmas Island flying-fox: implications for seed and pollen dispersal within a threatened island ecosystem

BACKGROUND

Animals are important vectors for the dispersal of a wide variety of plant species, and thus play a key role in maintaining the health and biodiversity of natural ecosystems. On oceanic islands, flying-foxes are often the only seed dispersers or pollinators. However, many flying-fox populations are currently in decline, particularly those of insular species, and this has consequences for the ecological services they provide. Knowledge of the drivers and the scale of flying-fox movements is important in determining the ecological roles that flying-foxes play on islands. This information is also useful for understanding the potential long-term consequences for forest dynamics resulting from population declines or extinction, and so can aid in the development of evidence-based ecological management strategies. To these ends, we examined the foraging movements, floral resource use, and social interactions of the Critically Endangered Christmas Island flying-fox (Pteropus natalis).

METHODS

Utilization distributions, using movement-based kernel estimates (MBKE) were generated to determine nightly foraging movements of GPS-tracked P. natalis (n = 24). Generalized linear models (GLMs), linear mixed-effect models (LMMs), and Generalized linear mixed-effects model (GLMMs) were constructed to explain how intrinsic factors (body mass, skeletal size, and sex) affected the extent of foraging movements. In addition, we identified pollen collected from facial and body swabs of P. natalis (n = 216) to determine foraging resource use. Direct observations (n = 272) of foraging P. natalis enabled us to assess the various behaviors used to defend foraging resources.

RESULTS

Larger P. natalis individuals spent more time foraging and less time traveling between foraging patches, traveled shorter nightly distances, and had smaller overall foraging ranges than smaller conspecifics. Additionally, larger individuals visited a lower diversity of floral resources.

CONCLUSIONS

Our findings suggest that smaller P. natalis individuals are the primary vectors of long-distance dispersal of pollen and digested seeds in this species, providing a vital mechanism for maintaining the flow of plant genetic diversity across Christmas Island. Overall, our study highlights the need for more holistic research approaches that incorporate population demographics when assessing a species' ecological services.

The important role of animal social status in vertebrate seed dispersal

Seed dispersal directly affects plant establishment, gene flow and fitness. Understanding patterns in seed dispersal is, therefore, fundamental to understanding plant ecology and evolution, as well as addressing challenges of extinction and global change. Our ability to understand dispersal is limited because seeds may be dispersed by multiple agents, and the effectiveness of these agents can be highly variable both among and within species. We provide a novel framework that links seed dispersal to animal social status, a key component of behaviour. Because social status affects individual resource access and movement, it provides a critical link to two factors that determine seed dispersal: the quantity of seeds dispersed and the spatial patterns of dispersal. Social status may have unappreciated effects on post-dispersal seed survival and recruitment when social status affects individual habitat use. Hence, environmental changes, such as selective harvesting and urbanisation, that affect animal social structure may have unappreciated consequences for seed dispersal. This framework highlights these exciting new hypotheses linking environmental change, social structure and seed dispersal. By outlining experimental approaches to test these hypotheses, we hope to facilitate studies across a wide diversity of plant-animal networks, which may uncover emerging hotspots or significant declines in seed dispersal.

Seed size-seed number trade-offs: influence of seed size on the density of fire-stimulated persistent soil seed banks

PREMISE

Does the seed size-seed number allocation trade-off model apply to long-term persistent soil seed banks? This trade-off between seed size versus number of seeds produced is usually applied at a single population on an annual basis. Our question is how this model might apply to close relatives that produce dormant seed forming long-term persistent soil seed banks. These two criteria allow a focus on divergent evolution of conspecifics and permits us to isolate seed size in the spectrum of life history traits that may be influencing seed traits, and on how seed size influences accumulation and persistence in the soil.

METHODS

In California, Arctostaphylos species only produce physiologically dormant seed that are fire-stimulated and that vary in seed size permitting seed size-seed bank density relationship as a test of the seed size-seed number allocation model. Soil seed banks of 10 species of Arctostaphylos were sampled with fruit volumes ranging from 21-1063 mm³ . Seed bank density was determined by hand extraction from soil samples.

RESULTS

We found that seed bank densities were significantly negatively related to fruit or seed size.

CONCLUSIONS

Rather than an issue of allocational trade-off between size and number, we interpret these results as reflecting seed predation and postfire seedling establishment. Seed bank densities, even after decades, generally were less than one or two-year's seed production, suggesting intense seed predation. Burial by scatter-hoarding rodents provided sufficient seeds deep enough for survival of fire. Variation on seed size suggests seedling establishment constraints, but it needs further research.

Mast seeding promotes evolution of scatter-hoarding

Many plant species worldwide are dispersed by scatter-hoarding granivores: animals that hide seeds in numerous, small caches for future consumption. Yet, the evolution of scatter-hoarding is difficult to explain because undefended caches are at high risk of pilferage. Previous models have attempted to solve this problem by giving cache owners large advantages in cache recovery, by kin selection, or by introducing reciprocal pilferage of 'shared' seed resources. However, the role of environmental variability has been so far overlooked in this context. One important form of such variability is masting, which is displayed by many plant species dispersed by scatterhoarders. We use a mathematical model to investigate the influence of masting on the evolution of scatter-hoarding. The model accounts for periodically varying annual seed fall, caching and pilfering behaviour, and the demography of scatterhoarders. The parameter values are based mostly on research on European beech (Fagus sylvatica) and yellow-necked mice (Apodemus flavicollis). Starvation of scatterhoarders between mast years decreases the population density that enters masting events, which leads to reduced seed pilferage. Satiation of scatterhoarders during mast events lowers the reproductive cost of caching (i.e. the cost of caching for the future rather than using seeds for current reproduction). These reductions promote the evolution of scatter-hoarding behaviour especially when interannual variation in seed fall and the period between masting events are large. This article is part of the theme issue 'The ecology and evolution of synchronized seed production in plants'.

Land-use change alters associations between personality and microhabitat selection

Ecologists commonly assess ecological patterns at the population level, focusing on the average response of all individuals within a population, but to predict how populations will respond to land-use change we must understand how changes to habitat differentially affect individuals within a population. For example, forest management is a widespread type of land-use that impacts wildlife through the loss of key habitat features, but individuals within a population may vary in their responses to this loss due to differences in habitat selection among individuals. Specifically, intraspecific variation in habitat selection has been linked to animal personalities (i.e., consistent behavioral differences among conspecifics), but previous research has not examined whether the relationship between personality and habitat selection is influenced by land-use change. To address this knowledge gap, we tested the hypothesis that land-use change alters the association between personality and microhabitat selection in small mammals. Specifically, we investigated two main questions: (1) To what extent are personality type and microhabitat selection correlated among conspecifics? (2) Does land-use change alter individual patterns of microhabitat selection? To answer these questions, we conducted a large-scale field experiment over 4 years, contrasting unmanaged forest (control) with managed forest (two silvicultural treatments) in Maine, USA. We examined the relationships between habitat selection and personality traits in deer mice (Peromyscus maniculatus) and southern red-backed voles (Myodes gapperi). We found that personality traits were correlated with microhabitat selection at multiple spatial scales. Furthermore, land-use change altered these patterns of selection; resulting in either the loss of personality-associated selection or in novel patterns of selection in managed forests. These findings suggest that promoting structural complexity at multiple spatial scales, such as by interspersing stands of mature forest with managed stands, may maintain a variety of intraspecific habitat selection patterns and the associated ecological outcomes.

The mutualism-antagonism continuum in Neotropical palm-frugivore interactions: from interaction outcomes to ecosystem dynamics

Frugivory, that is feeding on fruits, pulp or seeds by animals, is usually considered a mutualism when interactions involve seed dispersal, and an antagonism when it results in the predation and destruction of seeds. Nevertheless, most frugivory interactions involve both benefits and disadvantages for plants, and the net interaction outcomes thus tend to vary along a continuum from mutualism to antagonism. Quantifying outcome variation is challenging and the ecological contribution of frugivorous animals to plant demography thus remains little explored. This is particularly true for interactions in which animals do not ingest entire fruits, that is in seed‐eating and pulp‐eating. Here, we provide a comprehensive review of Neotropical palm–frugivore interactions, with a focus on how frugivore consumption behaviour (i.e. digestive processing, fruit‐handling ability and caching behaviour) and feeding types (fruit‐eating, pulp‐eating and seed‐eating) influence interaction outcomes at different demographic stages of palms. We compiled a total of 1043 species‐level palm–frugivore interaction records that explicitly captured information on which parts of palm fruits are eaten by animals. These records showed consumption of fruits of 106 Neotropical palm species by 273 vertebrate species, especially birds (50%) and mammals (45%), but also fish (3%) and reptiles (2%). Fruit‐eating involved all four taxonomic vertebrate classes whereas seed‐eating and pulp‐eating were only recorded among birds and mammals. Most fruit‐eating interactions (77%) resulted in positive interaction outcomes for plants (e.g. gut‐passed seeds are viable or seeds are successfully dispersed), regardless of the digestive processing type of vertebrate consumers (seed defecation versus regurgitation). The majority of pulp‐eating interactions (91%) also resulted in positive interaction outcomes, for instance via pulp removal that promoted seed germination or via dispersal of intact palm seeds by external transport, especially if animals have a good fruit‐handling ability (e.g. primates, and some parrots). By contrast, seed‐eating interactions mostly resulted in dual outcomes (60%), where interactions had both negative effects on seed survival and positive outcomes through seed caching and external (non‐digestive) seed dispersal. A detailed synthesis of available field studies with qualitative and quantitative information provided evidence that 12 families and 27 species of mammals and birds are predominantly on the mutualistic side of the continuum whereas five mammalian families, six mammal and one reptile species are on the antagonistic side. The synthesis also revealed that most species can act as partial mutualists, even if they are typically considered antagonists. Our review demonstrates how different consumption behaviours and feeding types of vertebrate fruit consumers can influence seed dispersal and regeneration of palms, and thus ultimately affect the structure and functioning of tropical ecosystems. Variation in feeding types of animal consumers will influence ecosystem dynamics via effects on plant population dynamics and differences in long‐distance seed dispersal, and may subsequently affect ecosystem functions such as carbon storage. The quantification of intra‐ and inter‐specific variation in outcomes of plant–frugivore interactions – and their positive and negative effects on the seed‐to‐seedling transition of animal‐dispersed plants – should be a key research focus to understand better the mutualism–antagonism continuum and its importance for ecosystem dynamics.

Phenotypic variation in urban environments: mechanisms and implications

In the past decade, numerous studies have explored how urbanisation affects the mean phenotypes of populations, but it remains unknown how urbanisation impacts phenotypic variation, a key target of selection that shapes, and is shaped by, eco-evolutionary processes. Our review suggests that urbanisation may often increase intraspecific phenotypic variation through several processes; a conclusion aligned with results from our illustrative analysis on tit morphology across 13 European city/forest population pairs. Urban-driven changes in phenotypic variation will have immense implications for urban populations and communities, particularly through urbanisation's effects on individual fitness, species interactions, and conservation. We call here for studies that incorporate phenotypic variation in urban eco-evolutionary research alongside advances in theory.

Fruit secondary metabolites shape seed dispersal effectiveness

Plant secondary metabolites (PSMs) play a central role in seed dispersal and fruit defense, with potential for large impacts on plant fitness and demography. Yet because PSMs can have multiple interactive functions across seed dispersal stages, we must systematically study their effects to determine the net consequences for plant fitness. To tackle this issue, we integrate the role of fruit PSMs into the seed dispersal effectiveness (SDE) framework. We describe PSM effects on the quantity and quality of animal-mediated seed dispersal, both in pairwise interactions and diverse disperser communities, as well as trade-offs that occur across dispersal stages. By doing so, this review provides structure to a rapidly growing field and yields insights into a critical process shaping plant populations.

Within-Species Trait Variation Can Lead to Size Limitations in Seed Dispersal of Small-Fruited Plants

The inability of small-gaped animals to consume very large fruits may limit seed dispersal of the respective plants. This has often been shown for large-fruited plant species that remain poorly dispersed when large-gaped animal species are lost due to anthropogenic pressure. Little is known about whether gape-size limitations similarly influence seed dispersal of small-fruited plant species that can show a large variation in fruit size within species. In this study, fruit sizes of 15 plant species were compared with the gape sizes of their 41 animal dispersers in the temperate, old-growth Białowieża Forest, Poland. The effect of gape-size limitations on fruit consumption was assessed at the plant species level, and for a subset of nine plant species, also at the individual level, and subindividual level (i.e., fruits of the same plant individual). In addition, for the species subset, fruit-seed trait relationships were investigated to determine whether a restricted access of small-gaped animals to large fruits results in the dispersal of fewer or smaller seeds per fruit. Fruit sizes widely varied among plant species (74.2%), considerably at the subindividual level (17.1%), and to the smallest extent among plant individuals (8.7%). Key disperser species should be able to consume fruits of all plant species and all individuals (except those of the largest-fruited plant species), even if they are able to consume only 28-55% of available fruits. Fruit and seed traits were positively correlated in eight out of nine plant species, indicating that gape size limitations will result in 49% fewer (in one) or 16–21% smaller seeds (in three plant species) dispersed per fruit by small-gaped than by large-gaped main dispersers, respectively. Our results show that a large subindividual variation in fruit size is characteristic for small-fruited plant species, and increases their connectedness with frugivores at the level of plants species and individuals. Simultaneously, however, the large variation in fruit size leads to gape-size limitations that may induce selective pressures on fruit size if large-gaped dispersers become extinct. This study emphasizes the mechanisms by which gape-size limitation at the species, individual and subindividual level shape plant-frugivore interactions and the co-evolution of small-fruited plants.

Movement syndromes of a Neotropical frugivorous bat inhabiting heterogeneous landscapes in Brazil

BACKGROUND

There is growing evidence that individuals within populations can vary in both habitat use and movement behavior, but it is still not clear how these two relate to each other. The aim of this study was to test if and how individual bats in a Stunira lilium population differ in their movement activity and preferences for landscape features in a correlated manner.

METHODS

We collected data on movements of 27 individuals using radio telemetry. We fitted a heterogeneous-space diffusion model to the movement data in order to evaluate signals of movement variation among individuals.

RESULTS

S. lilium individuals generally preferred open habitat with Solanum fruits, regularly switched between forest and open areas, and showed high site fidelity. Movement variation among individuals could be summarized in four movement syndromes: (1) average individuals, (2) forest specialists, (3) explorers which prefer Piper, and (4) open area specialists which prefer Solanum and Cecropia.

CONCLUSIONS

Individual preferences for landscape features plus food resource and movement activity were correlated, resulting in different movement syndromes. Individual variation in preferences for landscape elements and food resources highlight the importance of incorporating explicitly the interaction between landscape structure and individual heterogeneity in descriptions of animal movement.

Uniting niche differentiation and dispersal limitation predicts tropical forest succession

Tropical secondary forests are increasingly important for carbon sequestration and biodiversity conservation worldwide; yet, we still cannot accurately predict community turnover during secondary succession. We propose that integrating niche differentiation and dispersal limitation will generate an improved theoretical explanation of tropical forest succession. The interaction between seed sources and dispersers regulates seed movement throughout succession, and recent technological advances in animal tracking and molecular analyses enable us to accurately monitor seed movement as never before. We propose a framework to bridge the gap between niche differentiation and dispersal limitation. The Source-Disperser Limitation Framework (SDLF) provides a way to better predict secondary tropical forest succession across gradients of landscape disturbance by integrating seed sources and frugivore behavior.

The Critical Importance of Old World Fruit Bats for Healthy Ecosystems and Economies

Despite extensive documentation of the ecological and economic importance of Old World fruit bats (Chiroptera: Pteropodidae) and the many threats they face from humans, negative attitudes towards pteropodids have persisted, fuelled by perceptions of bats as being pests and undesirable neighbours. Such long-term negativity towards bats is now further exacerbated by more recent disease-related concerns, particularly associated with the current COVID-19 pandemic. There remains an urgent need to investigate and highlight the positive and beneficial aspects of bats across the Old World. While previous reviews have summarised these extensively, numerous new studies conducted over the last 36 years have provided further valuable data and insights which warrant an updated review. Here we synthesise research on pteropodid-plant interactions, comprising diet, ecological roles, and ecosystem services, conducted during 1985-2020. We uncovered a total of 311 studies covering 75 out of the known 201 pteropodid species (37%), conducted in 47 countries. The majority of studies documented diet (52% of all studies; 67 pteropodid species), followed by foraging movement (49%; 50 pteropodid species), with fewer studies directly investigating the roles played by pteropodids in seed dispersal (24%; 41 pteropodid species), pollination (14%; 19 pteropodid species), and conflict with fruit growers (12%; 11 pteropodid species). Pteropodids were recorded feeding on 1072 plant species from 493 genera and 148 families, with fruits comprising the majority of plant parts consumed, followed by flowers/nectar/pollen, leaves, and other miscellaneous parts. Sixteen pteropodid species have been confirmed to act as pollinators for a total of 21 plant species, and 29 pteropodid species have been confirmed to act as seed dispersers for a total of 311 plant species. Anthropogenic threats disrupting bat-plant interactions in the Old World include hunting, direct persecution, habitat loss/disturbance, invasive species, and climate change, leading to ecosystem-level repercussions. We identify notable research gaps and important research priorities to support conservation action for pteropodids.

Standardized Laboratory Methodology for the Evaluation of Foraging Strategies in Necrophilous Beetles: A Case Study of Necrophila (Calosilpha) brunnicollis (Coleoptera: Silphidae)

Precise data regarding feeding habits of necrobiont species are a key element of food web and evolutionary ecology. They can also be used to assess the utility and value of those species for forensic entomology, where obligatory necrophagous species in particular are considered good bioindicators of postmortem or preappearance interval. However, the feeding habits of many species are known only from anecdotal field observations, often reduced to vaguely defined categories-predatory, necrophagous, or omnivorous. To address this issue, we designed a simple, in vitro behavioral experiment allowing the quantification of food preferences. Next, we applied it on Necrophila (Calosilpha) brunnicollis (Kraatz, 1877), which is a common carrion beetle of East Asia with unresolved food preferences. The results suggest that this species is preferentially necrophagous, thus valuable for forensic research. Importantly, however, our experimental design allowed us to reveal that it also readily feeds on larvae of Diptera, although they compose a minor proportion of its diet. This methodology can be applied to other species, and it could provide evidence for future decision making in forensic research.

The importance of individual movement and feeding behaviour for long-distance seed dispersal by red deer: a data-driven model

BACKGROUND

Long-distance seed dispersal (LDD) has strong impacts on the spatiotemporal dynamics of plants. Large animals are important LDD vectors because they regularly transport seeds of many plant species over long distances. While there is now ample evidence that behaviour varies considerably between individual animals, it is not clear to what extent inter-individual variation in behaviour alters seed dispersal by animals.

METHODS

We study how inter-individual variation in the movement and feeding behaviour of one of Europe's largest herbivores (the red deer, Cervus elaphus) affects internal seed dispersal (endozoochory) of multiple plant species. We combine movement data of 21 individual deer with measurements of seed loads in the dung of the same individuals and with data on gut passage time. These data serve to parameterize a model of passive dispersal that predicts LDD in three orientations (horizontal as well as upward and downward in elevation).With this model we investigate to what extent per-seed probabilities of LDD and seed load vary between individuals and throughout the vegetation period (May-December). Subsequently, we test whether per-seed LDD probability and seed load are positively (or negatively) correlated so that more mobile animals disperse more (or less) seeds. Finally, we examine whether non-random associations between per-seed LDD probability and seed load affect the LDD of individual plant species.

RESULTS

The studied deer dispersed viable seeds of at least 62 plant species. Deer individuals varied significantly in per-seed LDD probability and seed loads. However, more mobile animals did not disperse more or less seeds than less mobile ones. Plant species also did not differ significantly in the relationship between per-seed LDD probability and seed load. Yet plant species differed in how their seed load was distributed across deer individuals and in time, and this caused their LDD potential to differ more than twofold. For several plant species, we detected non-random associations between per-seed LDD probability and seed load that generally increased LDD potential.

CONCLUSIONS

Inter-individual variation in movement and feeding behaviour means that certain deer are substantially more effective LDD vectors than others. This inter-individual variation reduces the reliability of LDD and increases the sensitivity of LDD to the decline of deer populations. Variation in the dispersal services of individual animals should thus be taken into account in models in order to improve LDD projections.

Individual specialization in the use of space by frugivorous bats

Natural populations are not homogenous systems but sets of individuals that occupy subsets of the species' niche. This phenomenon is known as individual specialization. Recently, several studies found evidence of individual specialization in animal diets. Diet is a critical dimension of a species' niche that affects several other dimensions, including space use, which has been poorly studied under the light of individual specialization. In this study, which harnesses the framework of the movement ecology paradigm and uses yellow-shouldered bats Sturnira lilium as a model, we ask how food preferences lead individual bats of the same population to forage mainly in different locations and habitats. Ten individual bats were radiotracked in a heterogeneous Brazilian savanna. First, we modelled intraspecific variation in space use as a network of individual bats and the landscape elements visited by them. Second, we developed two novel metrics, the spatial individual specialization index (SpatIS) and the spatial individual complementary specialization index (SpatICS). Additionally, we tested food-plant availability as a driver of interindividual differences in space use. There was large interindividual variation in space use not explained by sex or weight. Our results point to individual specialization in space use in the studied population of S. lilium, most probably linked to food-plant distribution. Individual specialization affects not only which plant species frugivores consume, but also the way they move in space, ultimately with consequences for seed dispersal and landscape connectivity.

Advancing an interdisciplinary framework to study seed dispersal ecology

Although dispersal is generally viewed as a crucial determinant for the fitness of any organism, our understanding of its role in the persistence and spread of plant populations remains incomplete. Generalizing and predicting dispersal processes are challenging due to context dependence of seed dispersal, environmental heterogeneity and interdependent processes occurring over multiple spatial and temporal scales. Current population models often use simple phenomenological descriptions of dispersal processes, limiting their ability to examine the role of population persistence and spread, especially under global change. To move seed dispersal ecology forward, we need to evaluate the impact of any single seed dispersal event within the full spatial and temporal context of a plant's life history and environmental variability that ultimately influences a population's ability to persist and spread. In this perspective, we provide guidance on integrating empirical and theoretical approaches that account for the context dependency of seed dispersal to improve our ability to generalize and predict the consequences of dispersal, and its anthropogenic alteration, across systems. We synthesize suitable theoretical frameworks for this work and discuss concepts, approaches and available data from diverse subdisciplines to help operationalize concepts, highlight recent breakthroughs across research areas and discuss ongoing challenges and open questions. We address knowledge gaps in the movement ecology of seeds and the integration of dispersal and demography that could benefit from such a synthesis. With an interdisciplinary perspective, we will be able to better understand how global change will impact seed dispersal processes, and potential cascading effects on plant population persistence, spread and biodiversity.

Potential role in seed dispersal revealed by experimental trials with captive southern muriquis (Brachyteles arachnoides)

Primates are great fruit consumers and disperse intact seeds from most of the plants they consume, but effective seed dispersal depends, amongst other factors, on handling behavior. Likewise, the treatment in gut and mouth may alter seed fate. Overall, frugivore and folivore-frugivore primates are recognized to provide beneficial gut treatment for Neotropical plant species, but this effect might be overlooked at species-specific levels. In this study, we assessed the role of the southern muriqui (Brachyteles arachnoides), an endangered and endemic primate living in restricted fragments of the Brazilian Atlantic Forest, on potential quality of seed dispersal of native plants. Our main goals were to understand the effect of seed ingestion by this large-bodied atelid on germination of defecated seeds and in seed recovery by offering wild fruits of native species to captive individuals. We found that seven out of nine plant species were defecated intact and were able to germinate. Of those seven, one species showed enhanced and another showed decreased germination potential after defecation, while three species germinated faster after being defecated. The remaining species showed no differences from control seeds. The two non-germinating species were heavily predated, and average seed recovery was lower than expected, suggesting high levels of seed predation. The largest species offered (Inga vulpina) showed the highest dispersal potential. Our data support an overall neutral or potentially positive role of southern muriquis in seed dispersal quality for seven out of nine Atlantic Forest plant species, highlighting these primates' potential to produce an effective seed rain.

The physiology of movement

Movement, from foraging to migration, is known to be under the influence of the environment. The translation of environmental cues to individual movement decision making is determined by an individual's internal state and anticipated to balance costs and benefits. General body condition, metabolic and hormonal physiology mechanistically underpin this internal state. These physiological determinants are tightly, and often genetically linked with each other and hence central to a mechanistic understanding of movement. We here synthesise the available evidence of the physiological drivers and signatures of movement and review (1) how physiological state as measured in its most coarse way by body condition correlates with movement decisions during foraging, migration and dispersal, (2) how hormonal changes underlie changes in these movement strategies and (3) how these can be linked to molecular pathways. We reveale that a high body condition facilitates the efficiency of routine foraging, dispersal and migration. Dispersal decision making is, however, in some cases stimulated by a decreased individual condition. Many of the biotic and abiotic stressors that induce movement initiate a physiological cascade in vertebrates through the production of stress hormones. Movement is therefore associated with hormone levels in vertebrates but also insects, often in interaction with factors related to body or social condition. The underlying molecular and physiological mechanisms are currently studied in few model species, and show -in congruence with our insights on the role of body condition- a central role of energy metabolism during glycolysis, and the coupling with timing processes during migration. Molecular insights into the physiological basis of movement remain, however, highly refractory. We finalise this review with a critical reflection on the importance of these physiological feedbacks for a better mechanistic understanding of movement and its effects on ecological dynamics at all levels of biological organization.

Frugivory and seed dispersal by chelonians: a review and synthesis

In recent years, it has become clear that frugivory and seed dispersal (FSD) by turtles and tortoises is much more common than previously thought. We here review published and unpublished records of chelonian FSD, and assess the role of chelonians as seed dispersers, from individual species to the community level. We first discuss the distribution of chelonian FSD and the characteristics of the fruit and/or seed species eaten and dispersed by chelonians. We then use the seed dispersal efficiency framework to explore the quantitative and qualitative components of seed dispersal by tortoises and turtles, embarking on a journey from when the fruits and/or seeds are consumed, to when and where they are deposited, and assess how efficient chelonians are as seed dispersers. We finally discuss chelonian FSD in the context of communities and of chelonians as megafauna. A substantial proportion of the world's aquatic and terrestrial turtles and a major part of testudinid tortoises (71 species in 12 families) include fruits and/or seeds in their diet; fruits of at least 588 plant species in 121 families are ingested and/or dispersed by chelonians. For some chelonians, overall or in certain seasons, fruit may even form the largest part of their diet. Contrary to seed dispersal by lizards, the other major reptilian frugivores, chelonian FSD is not an island phenomenon in terms of geographic distribution. Nevertheless, on islands tortoises are often among the largest native terrestrial vertebrates - or were until humans arrived. We synthesise our knowledge of chelonian FSD, and discuss the relevance of our findings for conservation and restoration, especially in relation to rewilding with large and giant tortoises.

Intraspecific differences in seed dispersal caused by differences in social rank and mediated by food availability

We use individual-based information on the behavior of wild female Japanese macaques in two consecutive years with different food availability (nut-rich vs. nut-poor) to test effects of dominance rank and nut fruiting on seed dispersal parameters. We predicted that social rank would affect dispersal (1) quantity, (2) quality, (3) species richness, and (4) percentage of berries in the diet in the nut-poor year, while these differences would disappear in the nut-rich year. We found seeds of nine fleshy-fruited plant species in the feces of the monkeys. The frequency of seed occurrence for two plant species (Viburnum dilatatum and Rosa multiflora) showed an interaction between dominance ranks and years; in the nut-poor year V. dilatatum seeds were more abundant among dominant females and R. multiflora among subordinates, while such inter-rank differences disappeared in the nut-rich year. Similarly, the intact ratio of V. dilatatum seeds was lower for dominants in the nut-poor year, while inter-rank variations disappeared in the nut-rich year. Finally, percentage of berries in diet and seed richness showed no inter-annual nor inter-rank variations. Our study highlights that differences in individuals’ social rank lead to within-group variation in seed dispersal services and that these differences are dependent on nut availability.

Defensive fruit metabolites obstruct seed dispersal by altering bat behavior and physiology at multiple temporal scales

The paradoxical presence of toxic chemical compounds in ripe fruits represents a balance between plant enemies and allies: chemical traits can defend seeds against antagonistic herbivores, seed predators, or fungal pathogens, but also can impose costs by repelling mutualistic seed dispersers, although the costs are often difficult to quantify. Seeds gain fitness benefits from traveling far from the parent plant, as they can escape from parental competition and elude specialized herbivores as well as pathogens that accumulate on adult plants. However, seeds are difficult to follow from their parent plant to their final destination. Thus, little is known about the factors that determine seed dispersal distance. We investigated this potential cost of fruit secondary compounds, reduced seed dispersal distance, by combining two data sets from previous work on a Neotropical bat-plant dispersal system (bats in the genus Carollia and plants in the genus Piper). We used data from captive behavioral experiments, which show how amides in ripe fruits of Piper decrease the retention time of seeds and alter food choices. With new analyses, we show that these defensive secondary compounds also delay the time of fruit removal. Next, with a behaviorally annotated bat telemetry data set, we quantified post-feeding movements (i.e., seed dispersal distances). Using generalized additive mixed models we found that seed dispersal distances varied nonlinearly with gut retention times as well as with the time of fruit removal. By interrogating the model predictions, we identified two novel mechanisms by which fruit secondary compounds can impose costs in terms of decreased seed dispersal distances: (1) small-scale reductions in gut retention time and (2) causing fruits to forgo advantageous bat activity peaks that confer high seed dispersal distances.

Intrinsic and extrinsic drivers of intraspecific variation in seed dispersal are diverse and pervasive

There is growing realization that intraspecific variation in seed dispersal can have important ecological and evolutionary consequences. However, we do not have a good understanding of the drivers or causes of intraspecific variation in dispersal, how strong an effect these drivers have, and how widespread they are across dispersal modes. As a first step to developing a better understanding, we present a broad, but not exhaustive, review of what is known about the drivers of intraspecific variation in seed dispersal, and what remains uncertain. We start by decomposing 'drivers of intraspecific variation in seed dispersal' into intrinsic drivers (i.e. variation in traits of individual plants) and extrinsic drivers (i.e. variation in ecological context). For intrinsic traits, we further decompose intraspecific variation into variation among individuals and variation of trait values within individuals. We then review our understanding of the major intrinsic and extrinsic drivers of intraspecific variation in seed dispersal, with an emphasis on variation among individuals. Crop size is the best-supported and best-understood intrinsic driver of variation across dispersal modes; overall, more seeds are dispersed as more seeds are produced, even in cases where per seed dispersal rates decline. Fruit/seed size is the second most widely studied intrinsic driver, and is also relevant to a broad range of seed dispersal modes. Remaining intrinsic drivers are poorly understood, and range from effects that are probably widespread, such as plant height, to drivers that are most likely sporadic, such as fruit or seed colour polymorphism. Primary extrinsic drivers of variation in seed dispersal include local environmental conditions and habitat structure. Finally, we present a selection of outstanding questions as a starting point to advance our understanding of individual variation in seed dispersal.

Consequences of intraspecific variation in seed dispersal for plant demography, communities, evolution and global change

As the single opportunity for plants to move, seed dispersal has an important impact on plant fitness, species distributions and patterns of biodiversity. However, models that predict dynamics such as risk of extinction, range shifts and biodiversity loss tend to rely on the mean value of parameters and rarely incorporate realistic dispersal mechanisms. By focusing on the mean population value, variation among individuals or variability caused by complex spatial and temporal dynamics is ignored. This calls for increased efforts to understand individual variation in dispersal and integrate it more explicitly into population and community models involving dispersal. However, the sources, magnitude and outcomes of intraspecific variation in dispersal are poorly characterized, limiting our understanding of the role of dispersal in mediating the dynamics of communities and their response to global change. In this manuscript, we synthesize recent research that examines the sources of individual variation in dispersal and emphasize its implications for plant fitness, populations and communities. We argue that this intraspecific variation in seed dispersal does not simply add noise to systems, but, in fact, alters dispersal processes and patterns with consequences for demography, communities, evolution and response to anthropogenic changes. We conclude with recommendations for moving this field of research forward.

Seed dispersal by dispersing juvenile animals: a source of functional connectivity in fragmented landscapes

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.

Land-use change and the ecological consequences of personality in small mammals

Many plants rely on animals for seed dispersal, but are all individuals equally effective at dispersing seeds? If not, then the loss of certain individual dispersers from populations could have cascade effects on ecosystems. Despite the importance of seed dispersal for forest ecosystems, variation among individual dispersers and whether land-use change interferes with this process remains untested. Through a large-scale field experiment conducted on small mammal seed dispersers, we show that an individual's personality affects its choice of seeds, as well as how distant and where seeds are cached. We also show that anthropogenic habitat modifications shift the distribution of personalities within a population, by increasing the proportion of bold, active, and anxious individuals and in-turn affecting the potential survival and dispersal of seeds. We demonstrate that preserving diverse personality types within a population is critical for maintaining the key ecosystem function of seed dispersal.

Diet composition of the lizard Podarcis lilfordi (Lacertidae) on 2 small islands: an individual-resource network approach

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.