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393 results for “seed dispersal”
Data from: Asynchrony between ant seed dispersal activity and fruit dehiscence of myrmecochorous plants
Phenological mismatch has received attention in plant-pollinator interactions, but less so in seed dispersal mutualisms. We investigated whether the seasonal availability of myrmecochorous seeds is well matched to the seasonal activity patterns of seed-dispersing ants. Methods We compared seasonal timing of seed removal by a keystone seed-dispersing ant, Aphaenogaster rudis, and fruit dehiscence of several species of plants whose seeds it disperses in a deciduous forest in southern Ontario, Canada. We examined the timing of elaiosome 'robbing' by the non-native slug, Arion subfuscus, and tested whether seed removal by ants declines in response to supplementation with additional elaiosome-bearing seeds (ant "satiation"). Key Results Seed removal from experimental depots peaked early in the season for all plant species, and that seed removal correlated with temperature. In contrast, elaiosome robbing by slugs increased late in the season and thus may disproportionately affect plants with late-dehiscing fruits. Ant colonies removed seeds at similar rates regardless of seed supplementation, indicating that satiation likely does not impact seasonal patterns of seed dispersal in this system. Fruits of the five myrmecochorous plant species in our study dehisced at discrete intervals throughout the season, with minimal overlap among species. Peak dehiscence did not overlap with peak seed removal for any plant species. Conclusions Fruit dehiscence of myrmecochorous plants and peak ant seed dispersal activity occur asynchronously. Whether future climate warming will shift ant and plant phenologies in ways that have consequences for seed dispersal remains an open question. In compliance with data protection regulations, please contact the publication office if you would like to have your personal information removed from the database.
Data from: Ant seed removal in a non-myrmecochorous Neotropical shrub: implications for seed dispersal
<p>This study investigated ant seed removal of <em>Piper sancti-felicis</em>, an early successional Neotropical shrub. Neotropical <em>Piper</em> are a classic example of bat-dispersed plants, but we suggest that ants are underappreciated dispersal agents. We identified eleven ant species from the genera <em>Aphaenogaster, Ectatomma, Paratrechina, Pheidole, Trachymyrmex, </em>and<em> Wasmannia </em>recruiting to and harvesting <em>P. sancti-felicis</em> seeds in forest edge and secondary forest sites at La Selva, Costa Rica. We also tested for differences in ant recruitment to five states in which ants can commonly encounter seeds: unripe fruit, ripe fruit, overripe fruit, bat feces, and cleaned seeds. Overall, ants harvested more seeds from ripe and overripe fruits than other states, but this varied among species. To better understand the mechanisms behind ant preferences for ripe/overripe fruit, we also studied how alkenylphenols, secondary metabolites found in high concentrations in <em>P. sancti-felicis</em> fruits, affected foraging behavior in one genus of potential ant dispersers, <em>Ectatomma</em>. We found no effects of alkenyl- phenols on recruitment of <em>Ectatomma</em> to fruits, and thus, these compounds are un- likely to explain differences in ant recruitment among fruits of different maturity. Considering that <em>P. sancti-felicis</em> seeds have no apparent adaptations for ant disper- sal, and few ants removed seeds that were cleaned of pulp, we hypothesize that most ants are harvesting its seeds for the nutritional rewards in the attached pulp. This study emphasizes the importance of ants as important additional dispersers of <em>P. sancti-felicis</em> and suggests that other non-myrmecochorous, vertebrate-dispersed plants may similarly benefit from the recruitment to fruit by ants.</p>
Data from: The timing of frugivore-mediated seed dispersal effectiveness
The seed dispersal effectiveness framework allows assessing mutualistic services from frugivorous animals in terms of quantity and quality. Quantity accounts for the number of seeds dispersed and quality for the probability of recruitment of dispersed seeds. Research on this topic has largely focused on the spatial patterns of seed deposition because seed fates often vary between microhabitats due to differences in biotic and abiotic factors. However, the temporal dimension has remained completely overlooked despite these factors – and even local disperser assemblages – can change dramatically during long fruiting periods. Here, we test timing effects on seed dispersal effectiveness, using as study case a keystone shrub species dispersed by frugivorous birds and with a fruiting period of nine months. We evaluated quantity and quality in different microhabitats of a Mediterranean forest and different periods of the fruiting phenophase. We identified the bird species responsible for seed deposition through DNA barcoding and evaluated the probability of seedling recruitment through a series of field experiments on sequential demographic processes. We found that timing matters: the disperser assemblage was temporally structured, seed viability decreased markedly during the plant's fruiting phenophase, and germination was lower for viable seeds dispersed in the fruiting peak. We show how small contributions to seed deposition by transient migratory species can result in a relevant effectiveness if they disperse seeds in a high-quality period for seedling recruitment. This study expands our understanding of seed dispersal effectiveness, highlighting the importance of timing and infrequent interactions for population and community dynamics.
Data from: Relative importance of pollen and seed dispersal across a Neotropical mountain landscape for an epiphtytic orchid.
Populations of many species are isolated within narrow elevation bands of Neotropical mountain habitat, and how well dispersal maintains genetic connectivity is unknown. We asked whether genetic structure of an epiphytic orchid, Epidendrum firmum, corresponds to gaps between Costa Rican mountain ranges, and how these gaps influence pollen and seed flow. We predicted that significant genetic structure exists among mountain ranges due to different colonization histories and limited gene flow. Furthermore, we predicted that pollen movement contributes more to gene flow than seeds because seeds are released into strong winds perpendicular to the narrow northwest-southeast species distribution, while the likely pollinators are strong fliers. Individuals from 12 populations and three mountain ranges were genotyped with nuclear microsatellites (nDNA) and chloroplast sequences (cpDNA). Genetic diversity was high for both markers, while nDNA genetic structure was low (FSTn = 0.020) and cpDNA structure was moderate (FSTc = 0.443). Significant cpDNA barriers occurred within and among mountain ranges, but nDNA barriers were not significant after accounting for geographic distance. Consistent with these contrasting patterns of genetic structure, pollen contributes substantially more to gene flow among populations than seed (mp/ms = 46). Pollinators mediated extensive gene flow, eroding nDNA colonization footprints, while seed flow was comparatively limited, possibly due to directional prevailing winds across linearly distributed populations. Dispersal traits alone may not accurately inform predictions about gene flow or genetic structure, supporting the need for research into the potentially crucial role of pollinators and landscape context in gene flow among isolated populations.
Data from: Covariation in abscission force and terminal velocity of wind-borne sibling seeds alters long distance dispersal projections
1. Despite the fact that seeds are unlikely to be identical—even among siblings within a maternal individual—dispersal models typically use one mean trait value to represent the ability of an entire species to disperse. Previous work has shown that the environmental conditions under which individuals leave the maternal site strongly affect how far seeds will travel. However, less is known about how trait variation within individuals contributes to dispersal or how such variation might interact with abiotic factors. 2. Here, we develop the use of an ergometer in a novel application to investigate variation in seed traits, specifically the force required for seed abscission and seed terminal velocity, exhibited by seeds from different locations within maternal capitula of the invasive species Carduus nutans (Asteraceae). 3. We find that seeds from the center of capitula are significantly easier to liberate and have slower falling velocities than siblings found near the edge of capitula. When abscission force is positively correlated with terminal velocity, slowly falling, easily abscised seeds are projected to travel much further than the average seed on slow winds. 4. Our experimental and theoretical results, which together show that within-individual variation can strongly affect model projections of species dispersal, have important implications for our broader understanding of population spread rates, the spatial structure of populations, metapopulation connectivity, and gene flow in the landscape.
Data from: Frugivore biodiversity and complementarity in interaction networks enhance landscape-scale seed dispersal function
1. Animal biodiversity matters for the provision of ecosystem functions derived from trophic activity. However, the mechanisms underlying this pattern remain elusive since animal abundance and diversity, which are the components commonly used for representing biodiversity, provide poor information about ecological complementarity in species assemblages. An approach based on species interaction networks may overcome this constraint. 2. Here, we relate frugivore biodiversity and frugivore-plant network structure with landscape-scale seed dispersal function. We sampled, for two years, and at fourteen plots with variable assemblages of frugivores and plants in the Cantabrian Range (N Spain), data on the abundance and diversity of frugivorous birds, the consumption of fleshy fruits of woody plants, and the landscape-scale patterns of avian seed deposition. As a measure of interaction complementarity in seed dispersal networks, we estimated the degree to which frugivore and plant species specialize in their interacting partners. 3. Specialization varied strongly across the seed dispersal networks of the different plots, being higher in networks harboring smaller bird species that dispersed mostly small-fruited plants, and also in networks with late-ripening, dominant fruiting species dispersed mostly by wintering birds. 4. Bird abundance markedly affected seed deposition. Plots harboring more birds received a higher density of dispersed seeds, and showed higher probabilities of seed arrival and seed deposition in open microhabitats. Bird diversity also had a positive effect on the density of dispersed seed and, to a lesser extent, seed arrival probability. Independently of frugivore abundance and diversity, the density of dispersed seeds increased in plots where seed dispersal networks showed a higher degree of specialization. 5. This study considers the structure of interaction networks to re-address the relationship between biodiversity and ecosystem functionality, evidencing that specialization in frugivore-plant networks drives the large-scale process of seed dispersal. These results encourage the consideration of interaction complementarity as an underlying mechanism linking animal biodiversity and trophic-related functions.
Data from: Seed dispersal effectiveness by a large-bodied invasive species in defaunated landscapes
Animal-dispersed plants are increasingly reliant on effective seed dispersal provided by small-bodied frugivores in defaunated habitats. In the Neotropical region the non-native wild pig (Sus scrofa) is expanding its distribution and we hypothesized that they can be a surrogate for seed dispersal services lost by defaunation. We performed a thorough analysis of their interaction patterns, interaction frequencies, seed viability and characteristics of the seed shadows they produce. We found 15,087 intact seeds in 56% of the stomachs and 5186 intact seeds in 90% of the scats analyzed, 95% of which were smaller than 10 mm in diameter. Wild pigs were the third most effective disperser among 21 extant frugivore species in a feeding trail experiment in terms of quantity of seeds removed and gut retention time was 70 ±23 h, indicating they can promote long distance seed dispersal. Seed survival after seed handling and gut passage by wild pigs was positively related with seed size, but large seeds were spat out and only smaller were defecated intact, for which we observed a positive or neutral effect on germination relative to manually de-pulped seeds. Finally, deposition of seeds were four times more frequent in unsuitable than suitable sites for seedling recruitment and establishment. Seed dispersal effectiveness by wild pigs is high in terms of the quantity of seeds dispersed but variable in terms of the quality of the service provided. Our study highlights that negative and positive effects delivered by non-native species should be examined in a case by case scenario.
Data from: Quantifying species contributions to ecosystem processes: a global assessment of functional trait and phylogenetic metrics across avian seed-dispersal networks
Quantifying the role of biodiversity in ecosystems not only requires understanding the links between species and the ecological functions and services they provide, but also how these factors relate to measurable indices, such as functional traits and phylogenetic diversity. However, these relationships remain poorly understood, especially for heterotrophic organisms within complex ecological networks. Here, we assemble data on avian traits across a global sample of mutualistic plant–frugivore networks to critically assess how the functional roles of frugivores are associated with their intrinsic traits, as well as their evolutionary and functional distinctiveness. We find strong evidence for niche complementarity, with phenotypically and phylogenetically distinct birds interacting with more unique sets of plants. However, interaction strengths—the number of plant species dependent on a frugivore—were unrelated to evolutionary or functional distinctiveness, largely because distinct frugivores tend to be locally rare, and thus have fewer connections across the network. Instead, interaction strengths were better predicted by intrinsic traits, including body size, gape width and dietary specialization. Our analysis provides general support for the use of traits in quantifying species ecological functions, but also highlights the need to go beyond simple metrics of functional or phylogenetic diversity to consider the multiple pathways through which traits may determine ecological processes.
Data from: Angiosperm fleshy fruits and seed dispersers: a comparative analysis of adaptation and constraints in plant-animal interactions
Variation in phenotypic traits of angiosperm fleshy fruits has been explained as the result of adaptations to their mutualistic seed dispersers. By analyzing the information available on fleshy fruit characteristics of 910 angiosperm species, I assess the hypothesis of evolutionary association between fruit phenotypic traits and type of seed disperser (birds, mammals, and mixed dispersers) and address explicitly and quantitatively alternative null hypotheses about phylogenetic effects. Phylogenetic affinity among plant taxa is accounted for by comparative methods including nested ANOVA, phylogenetic autocorrelation, and independent contrasts. Averaging over the 16 fruit traits examined, phylogenetic effects down to genus level explain 61% of total variance. Phylogenetic autocorrelations are strong among close relatives, reaching significance for 11 of the 16 fruit traits examined. When assessed by independent contrast methods, correlated evolution between type of disperser and fruit traits is confined to fruit diameter. Differences among dispersal syndromes in other traits vanish after accounting for phylogenetic effects. These analyses reveal that seed dispersal syndromes are not entirely interpretable as current adaptations to seed dispersers. Their status as exaptations can be assessed by combining experimental studies of natural selection on fruit size and rigorous comparative and cladistic tests of adaptational hypotheses.
Data from: Scatterhoarders drive long- and short-term population dynamics of a nut-producing tree, while pre-dispersal seed predators and herbivores have little effect
1.Both seed predators and herbivores can have profound effects on individual plant growth, reproduction and survival, but their population level effects are less well understood. While most plants interact with a suite of seed predators and herbivores over their life cycle, few studies incorporate the effects of multiple interacting partners and multiple life stages on plant population growth. 2.We constructed a matrix model using six years of data from a rare, seed-producing population of American chestnut (Castanea dentata). We combined field demographic data with published experimental results on the effects of pre-dispersal seed predators (weevils) and post-dispersal seed predators (scatter-hoarding vertebrates) and incorporated the effect of vertebrate herbivores estimated from the field data. We explored the impact of these three different animal interactions for short-term (transient) and long-term (asymptotic) tree population growth. In addition, we used the model to explore the conditions under which scatter-hoarding would function as a mutualism. 3.Seed predators had greater effect on both short- and long-term population growth than herbivores. Although weevil infestation can greatly reduce the probability of germination, pre-dispersal seed predators had smaller effects on both short- or long-term population growth than post-dispersal predators. The elasticities of weevil-related parameters were also small. The effect of browsers on both the short- and long-term population growth rate were the smallest of the effects studied. Post-dispersal seed predation affected population growth the most of the interactions studied. The probability of seed removal was amongst the largest elasticities, similar in magnitude to survival of large trees. 4.Synthesis Our results indicate that neither weevils nor the intensity of browse damage observed at our study site are likely to hinder tree regeneration or reintroduction, though both reduced population growth. Although researchers and forest managers often assume that seeds are unimportant for long-lived tree populations, our test of this assumption shows that scatterhoarders and other post-dispersal seed consumers can significantly limit natural regeneration. Forest management that alters scatterhoarder behaviour could have significant effects on tree population dynamics that are largely unexplored.
Data from: Scale-dependent responses of pollination and seed dispersal mutualisms in a habitat transformation scenario
Transformed habitats are the result of deliberate replacement of native species by an exotic monoculture, involving changes in biotic and abiotic conditions. Despite this, transformed habitats are becoming more common and constitute a major biodiversity change driver, little is known about the scale-dependent responses of plant-animal mutualisms. Aiming to test the multi-scale responses of pollination and seed dispersal in a habitat transformation scenario, we examined a gradient of native and transformed habitats at three spatial scales (0-50, 50-100, and 100-250 m), focused on a highly-specialized mutualistic system composed of a hemiparasitic mistletoe (Tristerix corymbosus) that is almost exclusively pollinated by a hummingbird (Sephanoides sephaniodes) and dispersed by an arboreal marsupial (Dromiciops gliroides). Even though mistletoes were found along the gradient, they were more abundant and more densely aggregated when the transformed habitat was dominant. Disperser and pollinator activity also increased as the transformed habitat become dominant, at the scale of 0-50 m and 50-100 m, respectively. Furthermore, crop size and disperser activity co-varied at broad and intermediate scales, whereas recruitment co-varied at intermediate and fine scales. Moreover, disperser activity and the number of seedlings were spatially associated, stressing D. gliroides' role in the recruitment of the mistletoe. Synthesis: This highly specialized mutualistic system seems to be responding positively to the habitat structure modifications associated with Eucalyptus plantations. However, the actual costs (e.g., reduced gene flow, increased herbivory) in these transformed habitats are yet to be assessed.
Data from: Proximity to roads disrupts rodents' contributions to seed dispersal services and subsequent recruitment dynamics
1. Seed dispersal and subsequent recruitment dynamics play a crucially important role in regulating species coexistence and structuring tree diversity in diverse forests. Wildlife, which can dually shape the tree recruitment process by simultaneously functioning as natural enemies and seed dispersers, are undergoing widespread changes in population and behaviour due to the detrimental effects of expanding global road networks. However, the impact of these changes on recruitment dynamics through the alteration of seed dispersal processes remains understudied. 2. Here, we assessed how roads affect animal-mediated recruitment dynamics from the seed to adult stages of trees using a ubiquitous vertebrate-seed model: rodents and acorns. To quantify the degree to which proximity to a road alters seed dispersal and regulates subsequent recruitment dynamics, we conducted seed dispersal and predation experiments, and investigated the natural recruitment of a dominant tree species (Quercus aliena) from September 2009 to July 2012 in a subtropical forest of central China. 3. Roads caused a decreased seed dispersal distance and increasing larder hoarding, demonstrating a weakened contribution of rodents to seed dispersal services. These patterns were stronger in the masting year than in the non-masting year. Correspondingly, seedlings, saplings, and adult trees had higher densities near roads than far from roads. Near roads, recruit transition rates (i.e., seedling-to-sapling and sapling-to-juvenile) were low, and the influential strength of conspecific adult density was weakened over these recruit transitions, indicating that space limitation and lottery competition, not conspecific negative density-dependent effects, approximately determined the near-road recruitment process. Furthermore, most adults near roads were young, and their ages matched the road ages. 4. Synthesis. Roads diminished animal-mediated seed dispersal services and disrupted subsequent recruitment dynamics in Q. aliena populations, thus weakening the key process promoting diversity in forest ecosystems. Given that these animal-regulated roles in recruitment dynamics are widespread stabilizing forces for tree coexistence, our findings suggest that the ubiquity of roads and their continued expansion will contribute to the increase in forests dominated by a relatively low number of species. Consequently, the growing expansion of road networks will ultimately cause profound changes in community composition and structure across diverse forests worldwide.
Agouti reintroduction recovers seed dispersal of a large-seeded tropical tree
<p>The aim of animal reintroductions has mainly been species recovery; only few reintroduction initiatives focus on ecosystem restoration. Therefore, reintroduction consequences on ecological interactions are seldom assessed. We used the interaction between a reintroduced population of agoutis (<i>Dasyprocta leporina</i>) and a vulnerable tropical endemic tree (<i>Joannesia princeps</i>) to examine reintroduction effects on seed dispersal and seedling establishment. To test the outcomes of this interaction we tracked seeds of <i>J. princeps</i> in two adjacent forest areas with and without reintroduced agoutis. We also assessed if dispersal distances affected seedling survival. To determine seed fate and dispersal distance we used spool-and-line tracking, together with camera traps to identify dispersers. Agoutis were the only species removing <i>J. princeps</i> seeds, thus dispersal only occurred where agoutis had been reintroduced; in the area without agoutis, all seeds remained intact on the soil, even one year after the experiment's beginning. At the reintroduction area, most seeds were preyed upon by agoutis but 7% remained dispersed and 2% germinated after ten months. Only seeds buried by agoutis were able to germinate. Most dispersed seeds were disperse 15 m or farther and longer dispersal distances benefited <i>J. princeps</i>, since seedlings farther from a conspecific adult tree had greater survival probability. Agoutis were also seen burying seeds of two other plant species; these mammals have the potential to benefit dozens of large-seeded species in our study system<span>. </span>Agouti reintroduction thus exemplifies the value of trophic rewilding programs to re-establish ecological interactions and restore ecosystem functioning.</p>
Data from: Seed and pollen dispersal distances in two African legume timber trees and their reproductive potential under selective logging
The natural regeneration of tree species depends on seed and pollen dispersal. To assess if limited dispersal could be critical for the sustainability of selective logging practices, we performed parentage analyses in two Central African legume canopy species displaying contrasted floral and fruit traits: Distemonanthus benthamianus and Erythrophleum suaveolens. We also developed new tools linking forward dispersal kernels with backward migration rates to better characterize long-distance dispersal. Much longer pollen dispersal in D. benthamianus (mean distance dp=700m, mp=52% immigration rate in 6 km2 plot, s=7% selfing rate) than in E. suaveolens (dp=294m, mp=22% in 2 km2 plot, s=20%) might reflect different insect pollinators. At a local scale, secondary seed dispersal by vertebrates led to larger seed dispersal distances in the barochorous E. suaveolens (ds=175m) than in the wind-dispersed D. benthamianus (ds=71m). Yet, seed dispersal appeared much more fat-tailed in the latter species (15-25% seeds dispersing >500m), putatively due to storm winds (papery pods). The reproductive success was correlated to trunk diameter in E. suaveolens and crown dominance in D. benthamianus. Contrary to D. benthamianus, E. suaveolens underwent significant assortative mating, increasing further the already high inbreeding of its juveniles due to selfing, which seems offset by strong inbreeding depression. To achieve sustainable exploitation, seed and pollen dispersal distances did not appear limiting, but the natural regeneration of E. suaveolens might become insufficient if all trees above the minimum legal cutting diameter were exploited. This highlights the importance of assessing the diameter structure of reproductive trees for logged species.
Data from: Loss of animal seed dispersal increases extinction risk in a tropical tree species due to pervasive negative density dependence across life stages
Overhunting in tropical forests reduces populations of vertebrate seed dispersers. If reduced seed dispersal has a negative impact on tree population viability, overhunting could lead to altered forest structure and dynamics, including decreased biodiversity. However, empirical data showing decreased animal-dispersed tree abundance in overhunted forests contradict demographic models which predict minimal sensitivity of tree population growth rate to early life stages. One resolution to this discrepancy is that seed dispersal determines spatial aggregation, which could have demographic consequences for all life stages. We tested the impact of dispersal loss on population viability of a tropical tree species, Miliusa horsfieldii, currently dispersed by an intact community of large mammals in a Thai forest. We evaluated the effect of spatial aggregation for all tree life stages, from seeds to adult trees, and constructed simulation models to compare population viability with and without animal-mediated seed dispersal. In simulated populations, disperser loss increased spatial aggregation by fourfold, leading to increased negative density dependence across the life cycle and a 10-fold increase in the probability of extinction. Given that the majority of tree species in tropical forests are animal-dispersed, overhunting will potentially result in forests that are fundamentally different from those existing now.
Data from: Successional status, seed dispersal mode and overstorey species influence tree regeneration in tropical rain-forest fragments in Western Ghats, India
The effects of fragmentation and overstorey tree diversity on tree regeneration were assessed in tropical rain forests of the Western Ghats, India. Ninety plots were sampled for saplings (1–5 cm diameter at breast height (dbh); 5×5-m plots) and overstorey trees (>9.55 cm dbh; 20×20-m plots) within two fragments (32 ha and 18 ha) and two continuous forests. We tested the hypotheses that fragmentation and expected seed-dispersal declines (1) reduce sapling densities and species richness of all species and old-growth species, and increase recruitment of early-successional species, (2) reduce the prevalence of dispersed recruits and (3) increase influence of local overstorey on sapling densities and richness. Continuous forests and fragments had similar sapling densities and species richness overall, but density and richness of old-growth species declined by 62% and 48%, respectively, in fragments. Fragments had 39% lower densities and 24% lower richness of immigrant saplings (presumed dispersed into sites as conspecific adults were absent nearby), and immigrant densities of old-growth bird-dispersed species declined by 79%. Sapling species richness (overall and old-growth) increased with overstorey species richness in fragments, but was unrelated to overstorey richness in continuous forests. Our results show that while forest fragments retain significant sapling diversity, losses of immigrant recruits and increased overstorey influence strengthen barriers to natural regeneration of old-growth tropical rain forests.
Data from: Response of ants to human-altered habitats with reference to seed dispersal of Corydalis giraldii Fedde (Papaveraceae)
Anthropogenic habitat disturbance has potential consequences for ant communities. However, there is limited information on the effects of ant responses on associated ecological processes such as seed dispersal. We investigated the effect of disturbance on the abundance, richness, and composition of ant communities and the resulting seed‐dispersal services for a herbaceous myrmecochore, Corydalis giraldii (Papaveraceae), in an undisturbed habitat (forest understory), moderately disturbed habitat (abandoned farm field), and highly disturbed habitat (road verge) on Qinling Mountains, China. In total, we recorded 13 ant species, and five out of these were observed to transport seeds. The community composition of dispersers was significantly different amongst habitats. The richness of the dispersers did not differ among the habitats, but their total abundance significantly varied across habitats and was recorded to decrease in the road verge by 21%, in comparison to abandoned farm fields. The major seed‐dispersing ant species in both the forest understory and abandoned farm field were large‐bodied (Myrmica sp. and Formica fusca, respectively), whereas the major seed‐dispersing ants found in the road verge were small‐bodied (Lasius alienus). This difference resulted in lower seed removal rates and dispersal distances in the road verge than in the other two habitats. The different dispersal patterns were attributed primarily to differences in dispersing ant abundance and identity, most likely in response to habitats with different degree of anthropogenic disturbance. The possible influence of disturbance on the ecological specialization of ant‐seed dispersal interaction was also discussed.
Data from: Pre-dispersal seed predators and fungi differ in their effect on Luehea seemannii capsule development, seed germination and dormancy across two Panamanian forests
Pre-dispersal seed predation can greatly reduce crop size affecting recruitment success. Additionally, non-fatal damage by seed predators may allow infection by fungi responsible for post-dispersal seed losses. The objectives of this study were (1) to quantify pre-dispersal seed predation and fungal infection in a Neotropical tree species, Luehea seemannii, that produces dehiscent fruits and wind-dispersed seeds, and (2) to link pre-dispersal effects on seed quality to seed survival in the soil. To examine how seed predators and fungi influence seed losses, mesh exclosures, fungicide and the combination of both treatments were applied to separate branches in the canopy of trees in Gamboa and Parque Natural Metropolitano (PNM), Panama. To determine if treatments affect seed viability and survival in the soil, half of the seeds collected from each treatment were buried for four weeks in forest soils and subsequently allowed to germinate before and after the breaking of dormancy. Overall, 24 percent of developing fruit were lost to insect attack. In contrast, fungi infected only 3 percent of seeds at the pre-dispersal stage. For seeds germinated directly after collection, fungicide significantly increased germination in the wetter site (Gamboa) but decreased germination in the drier site (PNM). The pre-dispersal insect exclosure treatment increased the fraction of seeds that remained dormant after burial in the soil. This result suggests that exposure to insect predators may cause physical damage to seeds that results in the loss of physical dormancy but does not necessarily increase the susceptibility of seeds to pathogen attack in the soil.
Data from: Divergent effects of forest edges on host distribution and seed disperser activity influence mistletoe distribution and recruitment
1. Species interactions define functional diversity and community stability across ecosystems, and depend on the spatial distribution, the habitat requirements, and the sensitivity to disturbances of all interacting partners. Hence, assessing the effects of such anthropogenic disturbances on multi-species interactions may be essential to improve adaptation and mitigation measures for biodiversity conservation. 2. We determined the importance of edge effects on the interaction and distribution of three keystone species in South American temperate rainforests: the hemiparasitic mistletoe Tristerix corymbosus, its main host (the liana Campsidium valdivianum) and its only seed disperser (the marsupial Dromiciops gliroides). 3. The discordant impacts of forest edges on host (positive) and seed disperser (negative) affected mistletoe distribution at large spatial scales, owing to the combined effects of increased dispersal limitation and decreased host availability. More importantly, marsupial abundance had contrasting effects on mistletoe abundance at small and large spatial scales – suggesting a potential trade-off between local and long-distance dispersal. 4. We found the number of adult mistletoes per host increased with host size, which likely indicates that mistletoe colonization accumulated over the host's life-span. However, the number of juveniles found per host peaked at medium-sized hosts, increased with marsupial abundance and host availability and showed a negligible response to edges. 5. Synthesis: The lack of spatial congruence between host and seed disperser probably explains the scarcity of mistletoes in the study area, although the discordant drivers of juvenile and adult distributions suggest that there is a trade-off between recruitment patterns but also potential dispersal limitation at small scales. In essence, the interdependence among species linked by (mutualistic and antagonistic) interactions makes them more sensitive to anthropogenic disturbance, exacerbating its impact on the diversity and functioning of forest ecosystems.
Data from: Landscape structure mediates zoochorous-dispersed seed rain under isolated pasture trees across distinct tropical regions
Context: Isolated pasture trees play an important role in forest recovery within fragmented tropical landscapes by attracting seed dispersers and facilitating seedling growth. However, studies with conflicting results have led to confusion about what drives variation in zoochorous-dispersed seed rain patterns under isolated tree canopies. Objectives: To assess the role of landscape and biological factors impacting zoochorous-dispersed seed rain under isolated pasture trees across three tropical regions of the world. Methods: We measured seed dispersal under 144 isolated pasture trees found in 12 fragmented tropical and sub-tropical landscapes in Australia, Colombia and Nigeria. Using linear mixed effect models, we modeled seed diversity, abundance, richness and evenness as functions of the biological features and landscape context of isolated trees. Results: Throughout all regions, the amount of woody vegetation surrounding trees in pastures was negatively related to rainforest seed diversity, evenness and abundance. Seed diversity and evenness increased significantly with the distance of isolated trees to forest fragments in the Australian sub-tropics, but elsewhere, seed diversity and evenness tended to decline with distance to forest, though not significantly. Conclusions: Our results suggest that the tree composition of landscapes surrounding isolated pasture trees is important for influencing zoochorous-dispersed seed rain, regardless of the region studied. Our study highlights the prominent role of landscape-scale, rather than local-scale factors on seed dispersal to isolated pasture trees, while providing strong evidence that early stage successional processes involving isolated pasture trees are similar throughout global tropical regions.
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
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OpenNeuro
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