Food resource richness increases seed disperser visitations and seed rain richness.

Within the context of global change, seed dispersal research often focuses on changes in disperser communities (i.e., seed dispersers, such as birds, in an area) resulting from habitat fragmentation. This approach may not be completely illustrative due to certain seed disperser communities being more robust to fragmentation. Additionally, this top-down approach overlooks how changing food resources on landscapes impacts resource tracking and, subsequently, seed dispersal. We hypothesized resource tracking may promote diffuse plant-animal dispersal mutualisms if resource richness is positively linked to disperser and seed rain richness. We predicted increasing food resource richness attracts more visits and species of avian dispersers, resulting in higher counts and greater species richness of seeds deposited at sites (i.e., seed rain). We tested this mechanism in two replicated field experiments using a model system with bird feeders positioned above seed traps. In the first experiment, we demonstrated resource presence skews seed rain. In the second experiment, we explored how species richness of food resources (0, 4, 8, or 12 species) affected the species richness and visitation of avian seed dispersers at feeders and in subsequent seed rain. Collectively, we observed a positive relationship between available food resources and seed rain, likely mediated by resource tracking behavior of avian dispersers. Our findings underscore a potential key mechanism that may facilitate ecological diversity, whereby accumulating species richness in the plant community attracts a more diverse seed disperser community and indirectly promotes more species in seed rain. Importantly, the resource tracking mechanism driving this potential positive feedback loop may also result in negative ecosystem effects if global change diminishes resource availability through homogenization processes, such as invasive species colonization. Future research should explore the bottom-up effects of global change on food resources and seed disperser behavior to complement the literature on changing disperser communities.

Invertebrate dispersal by waterbird species in neotropical wetlands / A dispersão de invertebrados por aves aquáticas na região neotropical

Abstract Endozoochory by waterbirds is particularly relevant to the dispersal of non-flying aquatic invertebrates. This ecological function exercised by birds has been demonstrated in different biogeographical regions, but there are no studies for the neotropical region. In this work, we identified propagules of invertebrates in faeces of 14 syntopic South American waterbird species representing six families, and hatched additional invertebrates from cultured faeces. We tested whether propagule abundance, species richness and composition varied among bird species, and between the cold and warm seasons. We found 164 invertebrate propagules in faecal samples from seven different waterbirds species, including eggs of the Temnocephalida and Notonectidae, statoblasts of bryozoans (Plumatella sp.) and ephippia of Cladocera. Ciliates (including Paramecium sp. and Litostomatea), nematodes and rotifers (Adineta sp. and Nottomatidae) hatched from cultured samples. Potential for endozoochory was confirmed for 12 of 14 waterbird species. Our statistical models suggest that richness and abundance of propagules are associated with bird species and not affected by seasonality. Dispersal by endozoochory is potentially important to a broad variety of invertebrates, being promoted by waterbirds with different ecological and morphological traits, which are likely to drive the dispersal of invertebrates in neotropical wetlands.

Resumo A endozoocoria promovida por aves aquáticas é particularmente relevante para a dispersão de invertebrados aquáticos não-voadores. Essa função ecológica exercida pelas aves tem sido demonstrada para diferentes regiões biogeográficas, porém, não existem estudos para a região neotropical. Neste trabalho nós identificamos propágulos de invertebrados encontrados em fezes de 14 espécies sintópicas de aves aquáticas da América do Sul, representando seis famílias de aves, e também invertebrados emergidos de amostras fecais cultivadas em laboratório. Testamos se a abundância, riqueza de espécies e composição de propágulos de invertebrados variavam entre as espécies de aves e entre estações. Nós encontramos 164 propágulos de invertebrados em amostras fecais de sete espécies de aves, incluindo ovos de Temnocephalida e Notonectidae, estatoblastos de briozoários (Plumatella sp.) e efípios de Cladocera. Ciliados (incluindo Paramecium sp. e Litostomatea), nematóides e rotíferos (Adineta sp. e Nottomatidae) eclodiram de amostras cultivadas. O potencial para endozoocoria foi confirmado para 12 das 14 espécies de aves aquáticas investigadas. Nossos modelos estatísticos sugerem que a riqueza e abundância de propágulos estão associadas às espécies de aves e não são afetadas pela sazonalidade. A dispersão por endozoocoria é importante para uma ampla variedade de invertebrados, sendo promovida por aves aquáticas com diferentes características ecológicas e morfológicas as quais provavelmente regulam a dispersão de invertebrados entre áreas úmidas neotropicais.

Invertebrate dispersal by waterbird species in neotropical wetlands

Abstract Endozoochory by waterbirds is particularly relevant to the dispersal of non-flying aquatic invertebrates. This ecological function exercised by birds has been demonstrated in different biogeographical regions, but there are no studies for the neotropical region. In this work, we identified propagules of invertebrates in faeces of 14 syntopic South American waterbird species representing six families, and hatched additional invertebrates from cultured faeces. We tested whether propagule abundance, species richness and composition varied among bird species, and between the cold and warm seasons. We found 164 invertebrate propagules in faecal samples from seven different waterbirds species, including eggs of the Temnocephalida and Notonectidae, statoblasts of bryozoans (Plumatella sp.) and ephippia of Cladocera. Ciliates (including Paramecium sp. and Litostomatea), nematodes and rotifers (Adineta sp. and Nottomatidae) hatched from cultured samples. Potential for endozoochory was confirmed for 12 of 14 waterbird species. Our statistical models suggest that richness and abundance of propagules are associated with bird species and not affected by seasonality. Dispersal by endozoochory is potentially important to a broad variety of invertebrates, being promoted by waterbirds with different ecological and morphological traits, which are likely to drive the dispersal of invertebrates in neotropical wetlands.

Resumo A endozoocoria promovida por aves aquáticas é particularmente relevante para a dispersão de invertebrados aquáticos não-voadores. Essa função ecológica exercida pelas aves tem sido demonstrada para diferentes regiões biogeográficas, porém, não existem estudos para a região neotropical. Neste trabalho nós identificamos propágulos de invertebrados encontrados em fezes de 14 espécies sintópicas de aves aquáticas da América do Sul, representando seis famílias de aves, e também invertebrados emergidos de amostras fecais cultivadas em laboratório. Testamos se a abundância, riqueza de espécies e composição de propágulos de invertebrados variavam entre as espécies de aves e entre estações. Nós encontramos 164 propágulos de invertebrados em amostras fecais de sete espécies de aves, incluindo ovos de Temnocephalida e Notonectidae, estatoblastos de briozoários (Plumatella sp.) e efípios de Cladocera. Ciliados (incluindo Paramecium sp. e Litostomatea), nematóides e rotíferos (Adineta sp. e Nottomatidae) eclodiram de amostras cultivadas. O potencial para endozoocoria foi confirmado para 12 das 14 espécies de aves aquáticas investigadas. Nossos modelos estatísticos sugerem que a riqueza e abundância de propágulos estão associadas às espécies de aves e não são afetadas pela sazonalidade. A dispersão por endozoocoria é importante para uma ampla variedade de invertebrados, sendo promovida por aves aquáticas com diferentes características ecológicas e morfológicas as quais provavelmente regulam a dispersão de invertebrados entre áreas úmidas neotropicais.

Dispersal syndromes of Vachellia caven: Dismantling introduction hypotheses and the role of man as a conceptual support for an archaeophyte in South America.

Vachellia caven has a disjunct distribution at the southern cone of South America, occupying two major ranges: west of Andes (Central Chile) and east of them (mainly the South American Gran Chaco). For decades, the species has been subject to various ecological and natural history studies across its distribution, but questions concerning its origin in the western range remain unresolved. Thus far, it is unclear whether Vachellia caven was always a natural component of the Chilean forests, and "how" and "when" the species arrived in the country. In this study, we revised the dispersal syndromes of the species and contrast the two main hypotheses of dispersion to the west of Andes that have been proposed in the 90's, namely animal versus human-mediated dispersal. For this, we reviewed all scientific literature on the species and explored the available information on morphology, genetics, fossil records and distribution patterns of closely related species. Here we illustrate how the collected evidence provides support for the human-mediated dispersal hypothesis, by including a conceptual synthesis that summarizes the outcomes of different dispersal scenarios. Lastly, and regarding the positive ecological effects this species has in the introduced area, we suggest reconsidering the (underappreciated) historical impacts of archaeophytes and rethinking the role that indigenous human tribes may have had in the dispersion of different plants in South America.

How Does Changing Environment Influence Plant Seed Movements as Populations of Dispersal Vectors Decline?

Plants differ widely in their ability to find tolerable climatic ranges through seed dispersal, depending on their life-history traits and habitat characteristics. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review on seed dispersal mechanisms was conducted to elucidate plant seed movements amid changing environments. Here, the highest relative count of studies was found in Spain (16.47%), followed by Brazil (14.12%), and the USA (14.12%). The megadiverse, hotspot countries (e.g., Philippines, Vietnam, Myanmar, India, and Indonesia) and Africa (Tanzania, South Africa, Democratic Republic of the Congo) have very low to no data about the reviewed topic. The effects of land use changes, habitat degradation/disturbances, climate, and extreme weather conditions on seed dispersal mechanisms and agents had the highest share of studies across topics and countries. Plant diversity and distribution of anemochorous, endozoochorous, epizoochorous, hydrochorous, myrmecochorous, and ornithochorous species are seriously affected by changing environments due to altered long-distance seed dispersal. The fruit types commonly associated with endozoochory and ornithochory are species with achene, capsule, drupe, fleshy, and nut fruits/seeds, whereas achene, capsule, samara/winged seeds are associated with anemochory. The present review provides a summary of evidence on how plants are affected by climate change as populations of dispersal vectors decline. Finally, recommendations for further study were made based on the identified knowledge gaps.

Animal-mediated plant niche tracking in a changing climate.

Over half of plant species are animal-dispersed, and our understanding of how animals can help plants move in response to climate change - a process known as niche tracking - is limited, but advancing rapidly. Recent research efforts find evidence that animals are helping plants track their niches. They also identify key conditions needed for animal-mediated niche tracking to occur, including alignment of the timing of seed availability, the directionality of animal movements, and microhabitat conditions where seeds are deposited. A research framework that measures niche tracking effectiveness by considering all parts of the niche-tracking process, and links together data and models from multiple disciplines, will lead to further insight and inform actions to help ecosystems adapt to a changing world.

Ecological Impacts of Exotic Species on Native Seed Dispersal Systems: A Systematic Review.

Exotic species are one of the main threats to biodiversity, leading to alterations in the structure and functioning of natural ecosystems. However, they can sometimes also provide ecological services, such as seed dispersal. Therefore, we assessed the ecological impacts of exotic species on native dispersal systems and the mechanisms underlying the disruption of mutualistic plant-disperser interactions. Exotic species negatively affect dispersal mutualisms by (i) altering dispersal behavior and visitation rates of native dispersers, (ii) predating native dispersers, (iii) transmitting forest pathogens, and (iv) predating seeds. Conversely, positive impacts include the dispersal of native plants, forest regeneration, and native habitat restoration via (i) increasing the visitation rates of frugivorous birds, (ii) facilitating the colonization and establishment of native forest trees, (iii) enhancing forest species seedling survival, and (iv) facilitating seed rain and seedling recruitment of early and late successional native plants. The reviewed studies provide similar results in some cases and opposite results in others, even within the same taxa. In almost all cases, exotic species cause negative impacts, although sometimes they are necessary to ensure native species' persistence. Therefore, exotic species management requires a comprehensive understanding of their ecological roles, since the resulting effects rely on the complexity of native-exotic species interactions.

Germination of fruits eaten by the maned wolf Chrysocyon brachyurus (Illiger, 1815) (Carnivora, Canidae) / Germinação de frutos consumidos pelo lobo-guará Chrysocyon brachyurus (Illiger, 1815) (Carnivora, Canidae)

Abstract Zoochory is a fundamental process that can be the main mechanism for seed and plant dispersal for many species. Mammals of the Carnivora order are among the most important dispersing agents; however, little is known regarding the role of canids as seed dispersers. Although the maned wolf (Chrysocyon brachyurus) has a potentially important role in seed dispersal, given its relatively high consumption of fruits, few studies have investigated the germination rate of ingested seeds. Here, we used seeds removed from the feces of two captive specimens (maned wolf treatment) and those directly collected from unconsumed fruits (control) in germination essays to evaluate the germination rate and emergence velocity index (IVE). We used mature fruits from five species of trees in the Cerrado and Atlantic Forest in a 5 (species) × 2 (method of seed collection) factorial arrangement. The passage of seeds through the digestive tract of the maned wolf favored the germination of Genipa americana and Psidium guajava, delayed germination of Psidium cattleianum, and maintained the germination of Plinia cauliflora and Ficus obtusifolia. Our results revealed that germination occurred for all tested plant species consumed by the maned wolf; therefore, this canid species has high dispersal potential and can be an important ally in the restoration of the Cerrado and Atlantic Forest-Cerrado contact zone ecosystems.

Resumo A zoocoria é um processo fundamental para muitas espécies vegetais, podendo ser o principal mecanismo de dispersão de sementes e plantas. Os mamíferos da ordem Carnivora estão entre os agentes dispersores mais importantes, contudo, pouca atenção tem sido dada ao papel dos canídeos como dispersores de sementes. Embora o lobo-guará (Chrysocyon brachyurus) tenha um papel potencialmente importante na dispersão de sementes dado o seu consumo relativamente elevado de frutos, poucos estudos investigaram a taxa de germinação de sementes ingeridas. Aqui utilizamos sementes retiradas de fezes de dois exemplares em cativeiro (tratamento do lobo-guará) e diretamente retiradas de frutos não consumidos (controle) em ensaios de germinação para avaliar a taxa de germinação e o índice de velocidade de emergência (IVE). Utilizamos frutos maduros de cinco espécies de árvores que ocorrem no Cerrado e Mata Atlântica formando um arranjo fatorial de 5 (espécie) × 2 (forma de coleta de sementes). A passagem das sementes pelo trato digestivo do lobo-guará favoreceu a germinação de duas espécies, Genipa americana e Psidium guajava, atrasou a germinação de uma espécie, Psidium cattleianum e não afetou a germinação de duas espécies, Plinia cauliflora e Ficus obtusifolia. Com base nos nossos resultados, particularmente a descoberta de que todas as espécies vegetais testadas consumidas pelo lobo-guará germinaram, concluímos que esta espécie de canídeo tem um elevado potencial de dispersão, sendo um importante aliado na restauração de ecossistemas do Cerrado e da zona de contato entre Cerrado e Mata Atlântica.

Silky dogwood (Swida amomum) seed dispersal by freshwater turtles.

PREMISE: Effective seed dispersal is essential to the success of plant species. Swida amomum (silky dogwood) has a seed-dispersal syndrome characteristic of autumn-ripening shrubs with fleshy fruits; attached fruits are ingested and defecated by birds, while fallen fruits are consumed by ground-foraging birds and mammals. METHODS: We documented that fallen fruits of this shrub were consumed by two aquatic turtle species (eastern painted turtle [Chrysemys picta] and red-eared slider [Trachemys scripta]) and that their seeds were defecated. We compared germination success (percentage of seeds germinated) of defecated seeds, seeds collected from a pond surface, and seeds removed from shrubs. RESULTS: While four seed species were identified in fecal samples, seeds of S. amomum were the most frequent (93%) among samples and the most numerous (106 seeds) in any sample. Average proportion of fecal seeds germinated (85.99%) exceeded that of seeds from the pond surface (82.76%) and from shrubs (60.24%), albeit the difference in germination success was insignificant. When analyzed using fecal samples from painted turtles only, the difference in germination success between fecal seeds and those collected from pond or shrub became significant. CONCLUSIONS: Our findings represent the first report of S. amomum seeds being dispersed by turtle gut passage and suggest aquatic turtles could be an important part of a secondary seed dispersal process influencing woody plant community composition in temperate wetland ecosystems.

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.

Unravelling the enigma of seed dispersal in Vanilla.

Vanilla bean is the second most expensive spice in the world. While widely cultivated for centuries due to its importance for industry and gastronomy, its dispersers are unknown. In the present study, I investigated the system of seed dispersal of Neotropical vanillas based on experimental observations, the morpho-anatomy of fruits and seeds, and the effect of dormancy breakdown on seed germination. My results show the central cavity of the fruit contains copious amounts of seed with sclerified coats that are consumed by birds. The combination of gradually opening dehiscent fruits and a well-developed mesocarp rich in raphide idioblasts reinforces the idea that seed dispersal in Vanilla is more adapted to non-chewing animals. The digestive acids of birds sclerify the hard seed coats, breaking dormancy and promoting germination at the beginning of the wet season, which is fundamental for seedling survival and for the establishment of plants in the early stages of development during the rainy season. Zoochory in Vanilla is show for the first time. The chemical scarification of the seed coat is crucial for synchronizing the biological processes involved in seed germination. My evidence on endozoochory and the processes involved in seed germination of Neotropical vanillas provides new insights into understanding of the early evolution of seed dispersal in orchids.

Epizoochory in Parrots as an Overlooked Yet Widespread Plant-Animal Mutualism.

Plant-animal interactions are key to sustaining whole communities and ecosystem function. However, their complexity may limit our understanding of the underlying mechanisms and the species involved. The ecological effects of epizoochory remain little known compared to other seed dispersal mechanisms given the few vectors identified. In addition, epizoochory is mostly considered non-mutualistic since dispersers do not obtain nutritional rewards. Here, we show a widespread but unknown mutualistic interaction between parrots and plants through epizoochory. Combining our observations with photos from web-sources, we recorded nearly 2000 epizoochory events in 48 countries across five continents, involving 116 parrot species and nearly 100 plant species from 35 families, including both native and non-native species. The viscid pulp of fleshy fruits and anemochorous structures facilitate the adherence of tiny seeds (mean 3.7 × 2.56 mm) on the surface of parrots while feeding, allowing the dispersion of these seeds over long distances (mean = 118.5 m). This parrot-plant mutualism could be important in ecosystem functioning across a wide diversity of environments, also facilitating the spread of exotic plants. Future studies should include parrots for a better understanding of plant dispersal processes and for developing effective conservation actions against habitat loss and biological invasions.

Phoresy in animals: review and synthesis of a common but understudied mode of dispersal.

Phoresy is a type of interaction in which one species, the phoront, uses another species, the dispersal host, for transportation to new habitats or resources. Despite being a widespread behaviour, little is known about the ecology and evolution of phoresy. Our goal is to provide a comprehensive review of phoretic dispersal in animals and to bring renewed attention to this subject. We surveyed literature published between 1900 and 2020 to understand the extent of known higher-level taxonomic diversity (phyla, classes, and orders) and functional aspects of animals that use phoretic dispersal. Species dispersing phoretically have been observed in at least 13 animal phyla, 25 classes, and 60 orders. The majority of known phoronts are arthropods (Phylum Euarthropoda) in terrestrial habitats, but phoronts also occur in freshwater and marine environments. Marine phoronts may be severely under-represented in the literature due to the relative difficulty of studying these systems. Phoronts are generally small with low mobility and use habitats or resources that are ephemeral and/or widely dispersed. Many phoronts are also parasites. In general, animals that engage in phoresy use a wide variety of morphological and behavioural traits for locating, attaching to, and detaching from dispersal hosts, but the exact mechanisms behind these activities are largely unknown. In addition to diversity, we discuss the evolution of phoresy including the long-standing idea that it can be a precursor to parasitism and other forms of symbioses. Finally, we suggest several areas of future research to improve our understanding of phoresy and its ecological and evolutionary significance.

Dispersal mode constrains allocation of carbon and mineral nutrients in seeds of forest and savanna trees.

Species vary in seed size and content of stored reserves, which can be related to dispersal strategies and type of habitat in which they are found. We compare seed carbon and nutrient reserves of anemochorous and zoochorous trees from the Cerrado of central Brazil. We measured seed dry mass, lipids, non-structural carbohydrates (starch and total soluble sugars), carbon and mineral nutrients in ten forest and 13 savanna species, each classified as having wind- or animal-dispersed seeds. We used phylogenetically independent contrasts to test for correlations among these traits. Seeds of anemochorous species were lighter, with higher concentrations of C, N, P, Ca and Mg. Lipids were the dominant carbon reserve for most anemochorous species, underpinning the importance of allocation to compact carbon reserves. Starch, lipids or soluble sugars were the major carbon reserve in zoochorous seeds. Savanna and forest species did not differ in seed mass or in total carbon reserves. However, seeds of forest species had higher concentrations of starch than seeds of savanna species. Lipid and starch negatively correlated across species, suggesting a trade-off between starch and lipids as major seed carbon reserves. Calcium was positively correlated with Mn and B, while Mg was positively correlated with C, N, P, K, S, Zn and B. Potassium, S and Cl were positively correlated, while P was positively correlated with Mg and Zn. Dispersal mode rather than vegetation type constrained seed mass and seed storage allocation patterns in forest and savanna trees. We provide evidence that similar mechanisms are involved in seed storage of carbon and mineral nutrients across species.

Ant removal distance, but not seed manipulation and deposition site increases the establishment of a myrmecochorous plant.

Myrmecochory (seed dispersal by ants) is a unique seed dispersal syndrome among invertebrates. It comprises three main phases: seed removal, seed manipulation, and seed deposition. However, the contribution of each phase to seed and seedling fate remains unclear. Here, we experimentally quantified the effects of each phase of myrmecochory on seed germination and seedling establishment, the two most critical life history stages involved in plant recruitment. We established 30 sample points, and each included an adult Mabea fistulifera tree, an Atta sexdens nest entrance, and six seed depots. We monitored the germination of M. fistulifera seeds for 3 months and subsequently followed the growth and mortality of the resulting seedlings for 12 months. Only the dispersal distance influenced plant establishment, reducing seed germination and increasing seedling growth, but with no effect of seed manipulation and deposition site. Despite the contrasting effects of distance on seed germination and seedling growth, the positive effect of dispersal distance on seedling growth was ten times greater than the negative effect on seed germination. Moreover, A. sexdens behaved neither as granivore nor as herbivore of M. fistulifera seeds or seedlings, which suggests that seed dispersal by A. sexdens is advantageous to M. fistulifera. Thus, the joint occurrence of these two species in disturbed areas could have a positive effect on this pioneer plant population, which might promote forest regeneration.

Estimating seed dispersal distance: A comparison of methods using animal movement and plant genetic data on two primate-dispersed Neotropical plant species.

Seed dispersal distance (SDD) critically influences the survival of seedlings, spatial patterns of genetic diversity within plant populations, and gene flow among plant populations. In animal-dispersed species, foraging behavior and movement patterns determine SDD. Direct observations of seed dispersal events by animals in natural plant populations are mostly constrained by the high mobility and low visibility of seed dispersers. Therefore, diverse alternative methods are used to estimate seed dispersal distance, but direct comparisons of these approaches within the same seed dispersal system are mostly missing.We investigated two plant species with different life history traits, Leonia cymosa and Parkia panurensis, exclusively dispersed by two tamarin species, Saguinus mystax and Leontocebus nigrifrons. We compared SDD estimates obtained from direct observations, genetic identification of mother plants from seed coats, parentage analysis of seedlings/saplings, and phenomenological and mechanistic modeling approaches.SDD derived from the different methods ranged between 158 and 201 m for P. panurensis and between 178 and 318 m for L. cymosa. In P. panurensis, the modeling approaches resulted in moderately higher estimates than observations and genotyping of seed coats. In L. cymosa, parentage analysis resulted in a lower estimate than all other methods. Overall, SDD estimates for P. panurensis (179 ± 16 m; mean ± SD) were significantly lower than for L. cymosa (266 ± 59 m; mean ± SD).Differences among methods were related to processes of the seed dispersal loop integrated by the respective methods (e.g., seed deposition or seedling distribution). We discuss the merits and limitations of each method and highlight the aspects to be considered when comparing SDD derived from different methodologies. Differences among plant species were related to differences in reproductive traits influencing gut passage time and feeding behavior, highlighting the importance of plant traits on animal-mediated seed dispersal distance.

Taxi drivers: the role of animals in transporting mycorrhizal fungi.

Dispersal of mycorrhizal fungi via animals and the importance for the interacting partners' life history as well as for ecosystems is an understudied topic. In this review, we describe the available evidence and the most important knowledge gaps and finally suggest ways to gain the missing information. So far, 33 articles have been published proving a successful transfer of mycorrhizal propagules by animals. The vast majority of research on invertebrates was focused on arbuscular mycorrhizal (AM) fungi, whereas papers on vertebrates (mainly rodents and artiodactyls) equally addressed ectomycorrhizal (ECM) and AM fungi. Effective dispersal has been mostly shown by the successful inoculation of bait plants and less commonly by spore staining or germination tests. Based on the available data and general knowledge on animal lifestyles, collembolans and oribatid mites may be important in transporting ECM fungal propagules by ectozoochory, whereas earthworms, isopods, and millipedes could mainly transfer AM fungal spores in their gut systems. ECM fungal distribution may be affected by mycophagous dipterans and their hymenopteran parasitoids, while slugs, snails, and beetles could transport both mycorrhizal groups. Vertebrates feeding on fruit bodies were shown to disperse mainly ECM fungi, while AM fungi are transported mostly accidentally by herbivores. The important knowledge gaps include insufficient information on dispersal of fungal propagules other than spores, the role of invertebrates in the dispersal of mycorrhizal fungi, the way in which propagules pass through food webs, and the spatial distances reached by different dispersal mechanisms both horizontally and vertically.