Find research datasets worth reusing
Search datasets from major research repositories and use ShareScore to quickly assess how well each record supports discovery, access, and reuse.
35
datasets available to search
ShareScore release 0.9.0
Dataset results
35 results for “defaunation”
Data from: Experimental defaunation alters foraging behavior of a small antelope in Kenya
Open the record for dataset details and reuse information.
Data from: Drivers and spatial patterns of avian defaunation in tropical forests
Open the record for dataset details and reuse information.
Data from: Defaunation increases clustering and fine-scale spatial genetic structure in a small-seeded palm despite remaining small-bodied frugivores
Open the record for dataset details and reuse information.
Data from: Defaunation increases the spatial clustering of lowland Western Amazonian tree communities
1.Declines of large vertebrates in tropical forests may reduce dispersal of tree species that rely on them, and the resulting undispersed seedlings might suffer increased distance- and density- dependent mortality. Consequently, extirpation of large vertebrates may alter the composition and spatial structure of plant communities and impair ecosystem functions like carbon storage. 2.We analysed spatial patterns of tree recruitment within six forest plots along a defaunation gradient in western Amazonia. We divided recruits into two size cohorts ("saplings", ≥1 m tall and <1 cm diameter at breast height [dbh], and juveniles, 1 – 2 cm dbh) and examined the spatial organization of conspecific recruits within each cohort (within-cohort) and around conspecific reproductive-sized trees (between-cohort). We used replicated spatial point pattern analysis to quantify relationships between recruit clustering and cohort, defaunation intensity, each tree species' reliance on hunted dispersers and the interactions among these three covariates. 3.Within-cohort clustering of conspecific saplings increased with reliance of tree species on hunted dispersers and this trend strengthened significantly as defaunation increased, probably because of reduced dispersal. 4.Within-cohort clustering of conspecifics declined from saplings to juveniles, suggesting density-dependent mortality of saplings. However, the positive relationship between sapling clustering and defaunation did not lead to greater reductions in within-cohort clustering during the sapling-juvenile transition, suggesting that higher conspecific densities did not translate into increased mortality. Instead, the increased spatial clustering associated with defaunation was retained for juvenile recruits. 5.Between-cohort clustering was unrelated to defaunation and did not change during the sapling – juvenile transition. 6.Synthesis: Defaunation increased spatial aggregation of saplings of tree species reliant on hunted dispersers. The increase in sapling clustering did not increase density-dependent thinning, and persisted into older recruit cohorts, suggesting that hunting may initiate long-term spatial reorganisation of Amazonian tree communities. The lack of increased density-dependent thinning indicates that reduced dispersal did not increase mortality of large-vertebrate dispersed tree species that contribute disproportionately to forest biomass. We therefore caution against the fait accompli acceptance of the prediction by recent modelling studies that overhunting will precipitate a collapse in carbon sequestration by tropical forests.
The interplay between defaunation and phylogenetic diversity affect leaf damage by natural enemies in tropical plants
<ol> <li>Natural enemies play an important role in controlling plant population growth and vegetation dynamics. Tropical rainforests host the greatest diversity of herbivores, from large mammalian ungulates to microscopic pathogens, generating and maintaining plant diversity.</li> <li>By feeding on the same resources, large mammalian herbivores may interfere with plant consumption and leaf damage by important enemy guilds such as invertebrate herbivores and pathogens, triggering indirect trophic cascades. However, the impact of local extinctions of large herbivores on plant-enemy interactions is relatively unknown.</li> <li>We experimentally tested the effects of defaunation of large mammalian herbivores (e.g., peccaries, tapirs, brocket deer; hereafter, large herbivores) on leaf damage of 3,350 understory plants in tropical rainforests of Brazil. We examined leaf damage in 10,050 leaves from 333 morphospecies by assigning the area consumed or damaged by five guilds of insect herbivores and leaf pathogens within 86 paired open-closed plots and investigated the joint effects of defaunation and plant phylogenetic diversity.</li> <li>Plants released from large herbivores had 9% less leaf damage; this difference was due to the lower leaf pathogens incidence (29%) rather than insect herbivory. Evolutionary Distinctness was similarly and positively correlated with leaf damage in all treatments, suggesting additive effects of defaunation and phylogenetic diversity. Total and pathogenic leaf damage (but not insect damage) decreased with plant richness across treatments, and large herbivores' exclusion resulted in increased plant species richness. This suggests that large herbivores' exclusion leads to a dilution of total and pathogens' leaf damage by increasing plant species richness.</li> <li>Our results suggest that large herbivores' indirect effects decrease the dilution potential of plant communities against pathogens and rather reinforce their top-down impact on vegetation, demonstrating a previously overlooked cascading effect of large herbivore extinction on forest ecosystems.</li> <li> <em>Synthesis</em>: The extinction of large mammalian herbivores can lead to a decrease in pathogen-driven leaf damage, a previously unknown indirect effect in forest ecosystems, which might have consequences for plant fitness and ultimately for plant diversity. Large herbivores and plant pathogens might have synergistic effects in regulating the diversity of plant communities in some of the most diverse ecosystems on Earth.</li> </ol>
The effect of past defaunation on ranges, niches, and future biodiversity forecasts
<p><span>Humans have reshaped the distribution of biodiversity across the globe, extirpating species from regions otherwise suitable and restricting populations to a subset of their original ranges. Here, we ask if anthropogenic range contractions since the Late Pleistocene led to an under‐representation of the realized niches for megafauna, an emblematic group of taxa often targeted for restoration actions. Using reconstructions of past geographic distributions (i.e., </span><em>natural ranges</em><span>) for 146 extant terrestrial large‐bodied (>44</span><span class="nonbreakingspace"> </span><span>kg) mammals, we estimate their climatic niches as if they had retained their original distributions and evaluate their observed niche dynamics. We found that range contractions led to a sizeable under‐representation of their realized niches (i.e., </span><em>niche unfilling</em><span>). For 29</span><span class="nonbreakingspace"> </span><span>species, more than 10% of the environmental space once seen in their natural ranges has been lost due to anthropogenic activity, with at least 12</span><span class="nonbreakingspace"> </span><span>species undergoing reductions of more than 50% of their realized niches. Eighteen species mainly now be confined to low‐suitability locations, where fitness and abundance are likely diminished; we consider these taxa </span><em>climatic refugees</em><span>. For those species, conservation strategies supported by current ranges risk being misguided if current, suboptimal habitats are considered baseline for future restoration actions. Because most climate‐based biodiversity forecasts rely exclusively on current occurrence records, we went on to test the effect of neglecting historical information on estimates of species' potential distribution – as a proxy of sensitivity to climate change. We found that niche unfilling driven by past range contraction leads to an overestimation of sensitivity to future climatic change, resulting in 50% higher rates of global extinction, and underestimating the potential for megafauna conservation and restoration under future climate change. In conclusion, range contractions since the Late Pleistocene have also left imprints on megafauna realized climatic niches. Therefore, niche truncation driven by defaunation can directly affect climate and habitat‐based conservation strategies.</span></p>
The effect of past defaunation on ranges, niches, and future biodiversity forecasts
Open the record for dataset details and reuse information.
The interplay between defaunation and phylogenetic diversity affect leaf damage by natural enemies in tropical plants
Open the record for dataset details and reuse information.
Data from: Defaunation increases the spatial clustering of lowland Western Amazonian tree communities
Open the record for dataset details and reuse information.
Changes in tree community structures in defaunated forests are not driven only by dispersal limitation
<p>1. Bushmeat hunting has reduced population sizes of large frugivorous vertebrates throughout the tropics, thereby reducing the dispersal of seeds. This is believed to affect tree population dynamics, and therefore community composition, because the seed dispersal of large-seeded trees depends upon large-bodied vertebrates.</p> <p>2. We report on a long-running study of the effect of defaunation on a tropical tree community. In three censuses over 11 years, we compared sapling recruitment between a hunted and a nonhunted site, which are nearby and comparable to one another, to determine the extent to which species composition has changed through time following defaunation. We expected to find a reduced abundance of tree species that rely on large frugivores for dispersal at the hunted site, and altered community structure as a consequence.</p> <p>3. Although community composition at the hunted site diverged from that at the nonhunted site, the changes were independent of dispersal syndrome, with no trend towards a decline in species that are dispersed by large, hunted vertebrates. Moreover, the loss of large-bodied dispersers did not generate the changes in tree community composition that we hypothesised. Some species presumed to rely on large-bodied frugivores for dispersal are effectively recruiting despite the absence of their dispersers.</p> <p>4. Synthesis: The presumption that forests depleted of large-bodied dispersers will experience rapid, directional compositional change is not fully supported by our results. Altered species composition in the sapling layer at the hunted site, however, indicates that defaunation may be connected with changes to the tree community, but that the nature of these changes are not unidirectional as previously assumed. It remains difficult to predict how defaunation will affect tree community composition without a deeper understanding of the driving mechanisms at play.</p>
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: The combined impacts of experimental defaunation and logging on seedling traits and diversity
Animals can have both positive (e.g. via seed dispersal) and negative (e.g. via herbivory) impacts on plants. The net effects of these interactions remain difficult to predict and may be affected by overhunting and habitat disturbance, two widespread threats to tropical forests. Recent studies have documented their separate effects on plant recruitment but our understanding of how defaunation and logging interact to influence tropical tree communities is limited. From 2013-2016, we followed the fate of marked tree seedlings (n = 1489) from 81 genera in and outside experimental plots. Our plots differentially excluded small, medium, and large-bodied mammal herbivores in logged and unlogged forest in Malaysian Borneo. We assessed the effects of experimental defaunation and logging on taxonomic diversity and plant trait (wood density, specific leaf area, fruit size) composition of seedling communities. Although seedling mortality was highest in the presence of all mammal herbivores (44%), defaunation alone did not alter taxonomic diversity nor plant trait composition. However, herbivores (across all body sizes) significantly reduced mean fruit size across the seedling community over time (95% CI: -0.09 to -0.01), particularly in logged forest (95% CI: -0.12 to -0.003). Our findings suggest that impacts of mammal herbivores on plant communities may be greater in forests with a history of disturbance and could subsequently affect plant functional traits and ecological processes associated with forest regeneration.
Data from: Vertebrate community composition and diversity declines along a defaunation gradient radiating from rural villages in Gabon
Anthropocene defaunation is the global phenomenon of human-induced animal biodiversity loss. Understanding the patterns and process of defaunation is critical to predict outcomes for wildlife populations and cascading consequences for ecosystem function and human welfare. We investigated a defaunation gradient in northeastern Gabon by establishing 24 transects at varying distances (2–30 km) to rural villages and surveying the abundance and composition of vertebrate communities. Distance from village was positively correlated with observations of hunting (shotgun shells, campfires, hunters), making it a good proxy for hunting pressure. Species diversity declined significantly with proximity to village, with mammal richness increasing by roughly 1.5 species every 10 km travelled away from a village. Compared to forest far from villages, the wildlife community near villages consisted of higher abundances of large birds and rodents and lower abundances of large mammals like monkeys and ungulates. Distance to nearest village emerged as a key driver of the relative abundance of five of the six taxonomic guilds, indicating that the top–down force of hunting strongly influences large vertebrate community composition and structure. Several measures of vegetation structure also explained animal abundance, but these varied across taxonomic guilds. Forest elephants were the exception: no measured variable or combination of variables explained variation in elephant abundances. Synthesis and applications. Hunting is concentrated within 10 km around villages, creating a hunting halo characterized by heavily altered animal communities composed of relatively small-bodied species. Although the strongest anthropogenic effects are relatively distance-limited, the linear increase in species richness shown here even at distances 30 km from villages suggests that hunting may have altered vertebrate abundances across the entire landscape. Central African forests store >25% of the carbon in tropical forests and are home to 3000 endemic species, but roughly 53% of the region lies within the village hunting halo. Resource management strategies should take into account this hunting-induced spatial variation in animal communities. Near villages, resource management should focus on sustainable community-led hunting programs that provide long-term supplies of wild meat to rural people. Resource management far from villages should focus on law enforcement and promoting industry practices that maintain remote tracts of land to preserve ecosystem services like carbon storage and biodiversity.
Data from: Experimental defaunation of terrestrial mammalian herbivores alters tropical rain forest understory diversity
It has been suggested that tropical defaunation may unleash community-wide cascading effects, leading to reductions in plant diversity. However, experimental evidence establishing cause–effect relationships thereof is poor. Through a 5 year exclosure experiment, we tested the hypothesis that mammalian defaunation affects tree seedling/sapling community dynamics leading to reductions in understorey plant diversity. We established plot triplets (n = 25) representing three defaunation contexts: terrestrial-mammal exclosure (TE), medium/large mammal exclosure (PE) and open access controls (C). Seedlings/saplings 30–100 cm tall were marked and identified within each of these plots and re-censused three times to record survival and recruitment. In the periods 2010–2011 and 2011–2013, survival was greater in PE than in C plots and recruitment was higher in TE plots than in C plots. Overall, seedling density increased by 61% in TE plots and 23% in PE plots, whereas it decreased by 5% in C plots. Common species highly consumed by mammals (e.g. Brosimum alicastrum and Ampelocera hottlei) increased in their abundance in TE plots. Rarefaction curves showed that species diversity decreased in TE plots from 2008 to 2013, whereas it remained similar for C plots. Given the prevalence of tropical defaunation, we posit this is an anthropogenic effect threatening the maintenance of tropical forest diversity.
Data from: Early genetic consequences of defaunation in a large-seeded vertebrate-dispersed palm (Syagrus romanzoffiana)
Plant populations are seriously threatened by anthropogenic habitat disturbance. In particular, defaunation may disrupt plant-disperser mutualisms, thus reducing levels of seed-mediated gene flow and genetic variation in animal-dispersed plants. This may ultimately limit their adaptive potential and ability to cope with environmental change. Tropical forest remnants are typically deprived of medium to large vertebrates upon which many large-seeded plants rely for accomplishing effective seed dispersal. Our main goal was to examine the potential early genetic consequences of the loss of large vertebrates for large-seeded vertebrate-dispersed plants. We compared the genetic variation in early-stage individuals of the large-seeded palm Syagrus romanzoffiana between continuous protected forest and nearby partially defaunated fragments in the Atlantic Forest of South America. Using nine microsatellites, we found lower allelic richness and stronger fine-scale spatial genetic structure in the disturbed area. In addition, the percentage of dispersed recruits around conspecific adults was lower, although not significantly, in the disturbed area (median values: 0.0 vs 14.4%). On the other hand, no evidence of increased inbreeding or reduced pollen-mediated gene flow (selfing rate and diversity of pollen donors) was found in the disturbed area. Our findings are strongly suggestive of some early genetic consequences resulting from the limitation in contemporary gene flow via seeds, but not pollen, in defaunated areas. Plant-disperser mutualisms involving medium–large frugivores, which are seriously threatened in tropical systems, should therefore be protected to warrant the maintenance of seed-mediated gene flow and genetic diversity in large-seeded plants.
Data from: Cascading effects of defaunation on the coexistence of two specialized insect seed predators
Identification of the mechanisms enabling stable coexistence of species with similar resource requirements is a central challenge in ecology. Such coexistence can be facilitated by species at higher trophic levels through complex multi-trophic interactions, a mechanism that could be compromised by ongoing defaunation. We investigated cascading effects of defaunation on Pachymerus cardo and Speciomerus giganteus, the specialized insect seed predators of the Neotropical palm Attalea butyracea, testing the hypothesis that vertebrate frugivores and granivores facilitate their coexistence. Laboratory experiments showed that the two seed parasitoid species differed strongly in their reproductive ecology. Pachymerus produced many small eggs that it deposited exclusively on the fruit exocarp (exterior). Speciomerus produced few large eggs that it deposited exclusively on the endocarp, which is normally exposed only after a vertebrate handles the fruit. When eggs of the two species were deposited on the same fruit, Pachymerus triumphed only when it had a long head start, and the loser always succumbed to intraguild predation. We collected field data on the fates of 6569 Attalea seeds across sites in central Panama with contrasting degrees of defaunation and wide variation in the abundance of vertebrate frugivores and granivores. Speciomerus dominated where vertebrate communities were intact, whereas Pachymerus dominated in defaunated sites. Variation in the relative abundance of Speciomerus across all 84 sampling sites was strongly positively related to the proportion of seeds attacked by rodents, an indicator of local vertebrate abundance. Synthesis. We show that two species of insect seed predators relying on the same host plant species are niche differentiated in their reproductive strategies such that one species has the advantage when fruits are handled promptly by vertebrates and the other when they are not. Defaunation disrupts this mediating influence of vertebrates and strongly favours one species at the expense of the other, providing a case study of the cascading effects of defaunation and its potential to disrupt coexistence of non-target species, including the hyperdiverse phytophagous insects of tropical forests.
Supplemental information, code, and data for the MS: Defaunation impacts carbon storage in tropical forests.
<p># MS_Carbon<br /> Supplemental information, code, and data for the MS: <br /> Carolina Bello, Mauro Galetti, Marco A. Pizo, Luiz Fernando S. Magnago, Mariana Ferreira Rocha, Renato A. F. Lima, Carlos A. Peres, Otso Ovaskainen, and Pedro Jordano (2015). Defaunation impacts carbon storage in tropical forests.</p> <p> </p> <p>*Summary*:<br /> Carbon storage is widely acknowledged as one of the most valuable forest ecosystem services. Deforestation, logging, fragmentation and climate change have significant impacts on tropical carbon stocks, however an elusive and yet undetected decrease in carbon storage may be due to defaunation of large seed dispersers. Many large tropical trees with sizeable contributions to carbon stock rely on large vertebrates for seed dispersal and regeneration, yet many of these frugivores are threatened by hunting, illegal trade and habitat loss. We used a large dataset on tree species composition and abundance, seed, fruit and carbon related traits, and plant-animal interactions to estimate the loss of carbon storage capacity of tropical forests in defaunated scenarios. By simulating the local extinction of trees that depend on large frugivores at 31 Atlantic Forest communities, we found that defaunation has the potential to significantly erode carbon storage even when only a small proportion (10%) of large-seeded trees are extirpated.</p> <p> </p>
Defaunated and invaded insular tropical rainforests will not recover alone: recruitment limitation factors disentangled by hierarchical models of spontaneous and assisted regeneration
<ol> <li>Most tropical forests are now severely degraded and their ability to recover is highly dependent on frugivores which ensure seed dispersal for most woody plants. The global collapse of large vertebrates therefore raises major concerns about tropical forest succession, but few field studies have been conducted to disentangle recruitment limitations during disrupted succession.</li> <li>This study took place on Réunion (Mascarenes) where all large native frugivores have been extinct since human colonisation in 1665 and where multiple invasions threaten native ecosystems. We set up 20 experimental blocks on a lava flow dated back to 1800, in plant-impoverished post-defaunation vegetation bordered by old-growth forests. We assessed fecundity, seed dispersal and seedling recruitment of the complete fleshy-fruited plant community and used Bayesian analyses to disentangle the impact of multiple factors on these key processes. In the same blocks, we sowed four native trees assumed to be disperserless to test their capacity to establish, controlling for two additional post-dispersal limitations (seed predation and competition with invasive plants).</li> <li>On the flow, small-seeded native plants were fairly dispersed but did not recruit, probably due to strong competition with invasive plants; the few native species that recruited somehow were mostly medium-seeded plants that were still dispersed; large-seeded plants were absent from seed rain (which shows that invasive frugivores did not replace extinct ones) and subsequently from spontaneous recruitment. Instead, some alien plants, notably the tiny-seeded highly-dispersed <em>Clidemia hirta</em> and the medium-seeded <em>Psidium cattleianum</em> largely dominated seedling recruitment. Native plants recruited better at the forest margin, including some large-seeded species nearby mother trees.</li> <li>Sown large-seeded species were able to emerge and survive in all plots whatever the treatment, which demonstrates that dispersal loss was the primary cause of regeneration failure on the flow. </li> <li> <em>Synthesis</em><strong>.</strong> The strong modulation of the establishment capacity of native plants by seed mass shows that invasive plants win by forfeit of large-seeded plants after native frugivores loss. Our study emphasises the fundamental role of dispersal loss and competition with invasive plants in the disruption of ecological succession, as well as the urgency of restoring seed dispersal and strengthening biosecurity regulations.</li> </ol>
Frugivory and seed dispersal in the Cerrado: Network structure and defaunation effects
<p><span>Seed dispersal is a fundamental process that is highly threatened by the rapid decline of large-bodied frugivores worldwide. The Brazilian Cerrado, the largest savanna in the world, represents an ideal site for investigating seed dispersal because of its biodiversity, environmental challenges, and knowledge shortfalls. We performed a Systematic Literature Review to analyze the seed dispersal network in the Cerrado and the potential impacts of the defaunation of large-bodied frugivores on it. We considered network metrics, calculated the defaunation index of the frugivore assemblage, and compared traits among different fruit-sized plants and their respective dispersers in the network. We retrieved 1,565 interactions involving 193 plant species and 270 animal species. Results show that the Cerrado seed dispersal network is slightly nested and considerably modular, dominated by small to medium-sized generalist species, such as passerines, marsupials, and mesocarnivores. Nonetheless, large-bodied frugivores like the lowland tapir have a key role in the network due to their great foraging and network integration capacity. The Cerrado frugivore assemblage is moderately defaunated, with possible effects in its interactions with large-fruited plants. The Cerrado's defaunation and functional loss of large vertebrates deserve urgent attention to further understand the impacts on seed dispersal mechanisms and ecosystem functioning.</span></p>
Data from: Seed dispersal effectiveness by a large-bodied invasive species in defaunated landscapes
Open the record for dataset details and reuse information.
ScienceDex guides
Understand access before you commit
These curated guides explain access requirements, typical timelines, costs, and reuse considerations for widely used research datasets.
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.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.