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165 results for “assemblage composition”
Data from: Bird assemblages on Amazonian river islands: patterns of species diversity and composition
The principles of island biogeography are rarely used to investigate the animal assemblages of Amazonian river islands. Here, we apply this approach to compare bird assemblages of Amazonian river islands with a variety of mainland habitats. We also examine how bird species diversity and composition are related to island physical attributes. Birds were sampled with mist nets and qualitative censuses on 11 river islands and at 24 mainland sites on the lower reaches of the Rio Negro in the Brazilian Amazon. Island bird assemblages are characterized by lower species richness and a higher abundance of a few dominant species. Additionally, species composition of the islands was significantly distinct from the mainland, including the nearby floodplain habitats. Number of bird species increased with island size and habitat diversity, and decreased with degree of isolation. In addition, small islands tended to harbour an impoverished subset of the species present on larger ones. Bird species diversity and composition on Amazonian river islands are likely influenced by the ecological succession and historical events affecting island formation. Considering their small total area across the Amazon basin, these insular fluvial environments could be disproportionally threatened by river channel disturbances such as climate change events, and hydroelectric building.
Data from: Taxonomic and phylogenetic determinants of functional composition of Bolivian bat assemblages
Understanding diversity patterns and the potential mechanisms driving them is a fundamental goal in ecology. Examination of different dimensions of biodiversity can provide insights into the relative importance of different processes acting upon biotas to shape communities. Unfortunately, patterns of diversity are still poorly understood in hyper-diverse tropical countries. Here, we assess spatial variation of taxonomic, functional and phylogenetic diversity of bat assemblages in one of the least studied Neotropical countries, Bolivia, and determine whether changes in biodiversity are explained by the replacement of species or functional groups, or by differences in richness (i.e., gain or loss of species or functional groups). Further, we evaluate the contribution of phylogenetic and taxonomic changes in the resulting patterns of functional diversity of bats. Using well-sampled assemblages from published studies we examine noctilionoid bats at ten study sites across five ecoregions in Bolivia. Bat assemblages differed from each other in all dimensions of biodiversity considered; however, diversity patterns for each dimension were likely structured by different mechanisms. Within ecoregions, differences were largely explained by species richness, suggesting that the gain or loss of species or functional groups (as opposed to replacement) was driving dissimilarity patterns. Overall, our results suggest that whereas evolutionary processes (i.e., historical connection and dispersal routes across Bolivia) create a template of diversity patterns across the country, ecological mechanisms modify these templates, decoupling the observed patterns of functional, taxonomic and phylogenetic diversity in Bolivian bats. Our results suggests that elevation represents an important source of variability among diversity patterns for each dimension of diversity considered. Further, we found that neither phylogenetic nor taxonomic diversity can fully account for patterns of functional diversity, highlighting the need for examining different dimensions of biodiversity of bats in hyperdiverse ecosystems.
Data from: Edge-mediated compositional and functional decay of tree assemblages in Amazonian forest islands after 26 years of isolation
1.Islands formed upstream of mega hydroelectric dams are excellent experimental landscapes to assess the impacts of habitat fragmentation on biodiversity. We examined the effects of plot-, patch- and landscape-scale variables on the patterns of floristic diversity across 34 forest islands that had experienced 26 years of isolation since the creation of the 4,437 km2 Balbina Hydroelectric Reservoir of central Brazilian Amazonia. In addition, three undisturbed continuous forest sites in neighbouring mainland areas were also sampled across a comparable elevational gradient. 2.We identified all live trees ≥10 cm DBH at species level within a total of 87 quarter-hectare forest plots and conducted a comprehensive compilation of functional attributes of each tree species. We then examined species-area relationships (SARs) and the additional effects of patch and landscape scale metrics on patterns of tree assemblage heterogeneity, both in terms of taxonomic and functional diversity. 3.Despite a clearly positive SAR, edge-mediated forest disturbance was the single most important driver of species composition and abundance within islands. Our results suggest that non-random floristic transitions within island plots followed a predictable pattern, with different life-history traits either penalizing or rewarding local persistence of different functional groups. Distance to edges mediated the probability of tree mortality induced by windfalls and episodic surface fires, clearly resulting in faster species turnover and unidirectional changes in guild structure within small islands where light-wooded fast-growing pioneers largely replaced heavy-wooded species of the old-growth flora. 3.Synthesis ─ Following a simultaneous 26-year post-isolation history, we disentangle the effects of habitat loss and insularization on tree assemblages within a large set of Amazonian 'true' forest islands, of variable sizes, sharing a uniform open-water matrix. Area effects are expressed via a response to edge effects, with trees in smaller islands being more vulnerable to edge-related surface fires and windthrows. Additionally, forest edge effects can be a powerful driver of non-random floristic transitions across islands within the Balbina archipelago via a process of rapid pioneer proliferation, drastically affecting both the taxonomic and functional composition of insular tree communities. Finally, our results indicate that detrimental effects of forest fragmentation induced by hydroelectric dams are considerably stronger than those of forest patches embedded within a terrestrial vegetation matrix.
Data from: Environmental constraints on the compositional and phylogenetic beta-diversity of tropical forest snake assemblages
The ongoing biodiversity crisis increases the importance and urgency of studies addressing the role of environmental variation on the composition and evolutionary history of species assemblages, but especially the tropics and ectotherms remain understudied. In regions with rainy summers, coexistence of ectothermic species may be determined by the partitioning of the climatic niche, since ectotherms can rely on water availability and thermoregulatory behaviour to buffer constraints along their climatic niche. Conversely, ectotherms facing dry summers would have fewer opportunities to climatic niche partitioning and other processes rather than environmental filtering would mediate species coexistence. We used 218 snake assemblages to quantify the compositional (CBD) and phylogenetic (PBD) beta-diversity of snakes in the Atlantic Forest (AF) hotspot. We identify two AF regions with distinct climatological regimes: dry summers in the northern-AF and rainy summers in the southern-AF. While accounting for the influence of multiscale spatial processes, we disentangle the relative contribution of thermal, water-related, and topographic conditions in structuring the CBD and PBD of snake assemblages, and determine the extent in which snake assemblages under distinct climatological regimes are affected by environmental filtering. Thermal conditions best explain CBD and PBD of snakes for the whole AF, whereas water-related factors best explain the structure of snake assemblages within a same climatological regime. CBD and PBD patterns are similarly explained by spatial factors but snake assemblages facing dry summers are more affected by spatial processes operating at fine to intermediate spatial scale whereas those assemblages in regions with rainy summers have a stronger signature of coarser-scale processes. As expected, environmental filtering plays a stronger role in southern-AF than northern-AF, and the synergism between thermal and water-related conditions is the key cause behind this difference. Differences in climatological regimes within the tropics may affect processes mediating species coexistence. The role of broad-scale gradients (e.g. temperature, precipitation) in structuring tropical ectothermic assemblages is greater in regions with rainy summers where climatic niche partitioning is more likely. Our findings highlight the potential stronger role of biotic interactions and neutral processes in structuring ectothermic assemblages facing changes towards warmer and dryer climates.
Data from: Present conditions may mediate the legacy effect of past land-use changes on species richness and composition of above- and below-ground assemblages
1. In forest ecosystems, the influence of landscape history on contemporary biodiversity patterns has been shown to provide a convenient framework to explain shifts in plant assemblages. However, very few studies have controlled for present human-induced activities when analyzing the effect of forest continuity on community structures. By cutting and removing trees, foresters substantially change stand ecological conditions, with consequences on biodiversity patterns. Disentangling the effect of past and present human activities on biodiversity is thus crucial for ecosystem management and conservation. 2. We explored the response of plant and springtail species richness and composition to forest continuity (ancient vs recent) in montane forests, while controlling for stand maturity (mature vs overmature). We established 70 sites in landscapes dominated by unfragmented ancient forests where we surveyed plants and assessed springtails by analyzing environmental DNA. 3. Neither plant nor springtail species richness was influenced by forest continuity or by stand maturity. Instead, site-specific characteristics, especially soil properties and canopy openness, were of major importance in shaping above- and below-ground richness. 4. For plant and springtail species composition, the effect of forest continuity was mediated by stand maturity. Thus, both plants and springtails showed a convergence in assemblage patterns with the increasing availability of overmature stand attributes. Moreover, soil and stand-scale factors were evidently more important than landscape-scale factors in shaping above- and below-ground species composition. 5. Synthesis. We clearly demonstrated that biodiversity patterns are more strongly influenced by present human-induced activities than by past human-induced activities. In the Northern Alps where our study sites were located, the colonization credit of most species has been paid off and the transient biodiversity deficit usually related to forest continuity has moved toward equilibrium. These findings emphasize the necessity to better control for local-scale factors when analyzing the response of biodiversity to forest continuity; we call for more research into the effects of forest continuity in unfragmented mountain forests.
Taxonomic and functional compositions and environmental data of 19 seedling assemblages in a Caatinga dry forest
<p>We used these information to assess the structure, composition, and diversity of woody seedling assemblages across 19 forest stands in a human-modified landscape of Caatinga dry forest, assessing the role played by rainfall, aboveground biomass, and chronic anthropogenic disturbances (i.e., livestock grazing pressure and wood extraction) as assembly forces. We quantified a large set of community-level attributes including functional traits related to water availability, physical protection, and survival success. We recorded a total of 544 seedlings from 59 species.</p>
Experimental evidence that host species composition alters host-pathogen dynamics in a ranavirus-amphibian assemblage
<p>Losses in biodiversity can alter disease risk through changes in host species composition. Host species vary in pathogen susceptibility and competence. Yet how changes in diversity alter host-pathogen dynamics remains unclear in many systems, particularly with respect to generalist pathogens. Amphibians are experiencing worldwide population declines linked to generalist pathogens, such as ranavirus, and thus represent an ideal group to investigate how host species composition affects disease risk. We conducted experiments where individuals in the laboratory and assemblages of three amphibian species (Pacific tree frogs, Pseudacris regilla; Cascades frogs, Rana cascadae; and Western toads, Anaxyrus boreas) or just A. boreas alone in outdoor mesocosms were exposed to ranavirus as larvae. In laboratory experiment, we observed low survival and high viral loads in P. regilla compared to the other species suggesting that this species was highly susceptible to the pathogen. In the mesocosm experiment, we observed 41% A. boreas mortality when alone and 98% mortality when maintained with P. regilla and R. cascadae. Our results suggest that the presence of highly susceptible species can alter disease dynamics across multiple species, potentially increasing infection risk and mortality in co-occurring species.</p>
Data related to article: Shrubs exhibit competitive interactions with herbaceous plants and shape community assemblage and functional composition in alpine western Himalaya
<p>To understand the interaction between dominant shrubs and herbacous communities in the alpine region of western Himalaya, a field study was conducted along the elevation gradient (3500-5000 masl). During the field survey, we have collected population data, plant functional trait data and soil physico-chemical data from shrub undercanopy and adjacent open habitats. Relative Interaction Index and L0g ratio were calculated using the population data. Further, plant functional traits data and soil physicochemical data were utilised to understand the functional comoposition and resource availability occuring in the contrasting habitats.</p>
Fig. 3 in Structure and Composition of Dung Beetle Assemblages (Coleoptera: Scarabaeidae) in a Livestock Ranch in Central Uruguay: Responses of Functional Groups and Species to Local Habitats and Trophic Resources
Fig. 3. Dominance/diversity curves based on a) abundance and b) biomass of the dung beetle species of Scarabaeidae in three habitats in Puntas de Sauce Maciel, Florida, Uruguay. PHS = pasture on humid soil; PDS = pasture on dry soil; EP = Eucalyptus plantation.
Fig. 1. a in Structure and Composition of Dung Beetle Assemblages (Coleoptera: Scarabaeidae) in a Livestock Ranch in Central Uruguay: Responses of Functional Groups and Species to Local Habitats and Trophic Resources
Fig. 1. a) Sample completeness curves as a function of dung beetle abundance in three study habitats in Puntas de Sauce Maciel, Florida, Uruguay, b) Coverage-based rarefaction (solid lines) and extrapolation (dash above endpoint for PHS) sampling curves for species richness of the dung beetle data from the three habitats. PHS = pasture on humid soil; PDS = pasture on dry soil; EP = Eucalyptus plantation.
Fig. 2 in Structure and Composition of Dung Beetle Assemblages (Coleoptera: Scarabaeidae) in a Livestock Ranch in Central Uruguay: Responses of Functional Groups and Species to Local Habitats and Trophic Resources
Fig. 2. Diversity profiles for dung beetle assemblages in three habitats in Puntas de Sauce Maciel, Florida, Uruguay as a function of Hill numbers (q) with 95% confidence intervals (shaded areas). PHS = pasture on humid soil; PDS = pasture on dry soil; EP = Eucalyptus plantation.
Fig. 4 in Structure and Composition of Dung Beetle Assemblages (Coleoptera: Scarabaeidae) in a Livestock Ranch in Central Uruguay: Responses of Functional Groups and Species to Local Habitats and Trophic Resources
Fig. 4. Detrended correspondence analysis ordination of dung beetle species sampled with baited pitfall traps in three different habitats in Puntas de Sauce Maciel, Florida, Uruguay. PHS = pasture on humid soil; PDS = pasture on dry soil; EP = Eucalyptus plantation.
Data from: Taxonomic and functional composition of arthropod assemblages across contrasting Amazonian forests
Arthropods represent most of global biodiversity, with the highest diversity found in tropical rainforests. Nevertheless, we have a very incomplete understanding of how tropical arthropod communities are assembled. We conducted a comprehensive mass-sampling of arthropod communities within three major habitat types of lowland Amazonian rainforest, including terra firme clay, white-sand, and seasonally-flooded forests in Peru and French Guiana. We examined how taxonomic and functional composition (at the family level) differed across these habitat types in the two regions. The overall arthropod community composition exhibited strong turnover among habitats and between regions. In particular, seasonally-flooded forest habitats of both regions comprised unique assemblages. Overall, 17.7% (26 of 147) of arthropod families showed significant preferences for a particular habitat type. We present a first reproducible arthropod functional classification among the 147 taxa based on similarity among 21 functional traits describing feeding source, major mouthparts and microhabitats inhabited by each taxon. We identified seven distinct functional groups whose relative abundance contrasted strongly across the three habitats, with sap and leaf feeders showing higher abundances in terra firme clay forest. Our novel arthropod functional classification provides an important complement to link these contrasting patterns of composition to differences in forest functioning across geographic and environmental gradients. This study underlines that both environment and biogeographical processes are responsible for driving arthropod taxonomic composition while environmental filtering is the main driver of the variance in functional composition.
Figure 2 in Multi-scale patterns in the host specificity of plant-dwelling arthropods: the influence of host plant and temporal variation on species richness and assemblage composition of true bugs (Hemiptera)
Figure 2. Non-metric multi-dimensional scaling (MDS) ordination showing hemipteran composition for all sampling periods with selected plant species superimposed.
Figure 5 in Multi-scale patterns in the host specificity of plant-dwelling arthropods: the influence of host plant and temporal variation on species richness and assemblage composition of true bugs (Hemiptera)
Figure 5. Annual cyclic pattern of the proportion of the effectively specialized fauna (squares) and singleton species (circles) for the total number of hemipteran species from each sampling period.
Figure 3 in Multi-scale patterns in the host specificity of plant-dwelling arthropods: the influence of host plant and temporal variation on species richness and assemblage composition of true bugs (Hemiptera)
Figure 3. Mean number of individuals (from SIMPER analysis) of dominant hemipteran species, during each sampling period, for most plant species.
Figure 1 in Multi-scale patterns in the host specificity of plant-dwelling arthropods: the influence of host plant and temporal variation on species richness and assemblage composition of true bugs (Hemiptera)
Figure 1. Interactions between plant species sampled and sampling period for (A) abundance (number of individuals) per plant and (B) species richness per plant (standard error bars are shown).
Figure 6 in Multi-scale patterns in the host specificity of plant-dwelling arthropods: the influence of host plant and temporal variation on species richness and assemblage composition of true bugs (Hemiptera)
Figure 6. Relationship between the effectively specialized fauna (squares) and singleton species (circles) for the number of hemipteran species from each sampling period and for the entire collection. An exponential decay equation is fitted for effectively specialized fauna, y = 2.973∗ exp (−0.00575∗ x) + (−1.478), R2 = 0.7598, and for singleton species, y = 22.53∗exp (−0.08466∗x) + 0.2614, R2 = 0.9873.
Climate overrides the effects of land use on the functional composition and diversity of mediterranean reptile assemblages.
<p>Aim: To test the hypothesis that spatial variations in climate and land use explain the distribution and diversity of reptiles' ecological traits in a biodiversity hotspot of the Mediterranean basin.</p> <p>Location: French Mediterranean region</p> <p>Taxon: Reptiles (25 species)</p> <p>Methods: We defined 288 species assemblages from 27858 opportunistic occurrence records within 10 x 10 km square grid cells. Using a RLQ analysis, we investigated the distribution of nine ecological traits describing reptiles' reproductive, dietary and behavioural strategies along environmental gradients formed by 10 climatic, topographic and land-use descriptors. After homogenizing survey effort through rarefaction, we used generalized additive models to assess variations in species richness and several measures of functional diversity and composition along these gradients. </p> <p>Results: Although ecological traits were not structured by environmental gradients at a species level, species richness and all measures of functional diversity varied non-linearly with climate, elevation and secondarily land use. Species richness and body size peaked at intermediate altitudes, indicating a climatic transition zone between Mediterranean and medio-european herpetofaunas. Conversely, functional diversity increased from Mediterranean plains, dominated by urbanization and agriculture, to higher elevations. These changes were associated with shifts towards less productive, more diurnal and more forest-related species.</p> <p>Main conclusions: Species-scale patterns are insufficient to assess regional variations in ecological traits in space. Our results support the hypothesis that climatic limitations in species' distributions, rather than environmental filtering, explain the taxonomic and ecological diversity of reptiles at a regional scale. Although secondary to climate, land abandonment has a strong structuring effect which may contribute to homogenize the composition of reptile assemblages.</p>
Data from: Influence of abiotic and biotic factors on benthic marine community composition, structure and stability: a multidisciplinary approach to molluscan assemblages from the Miocene of northern Germany
<p><span>The Miocene mica-clay deposits of Groß Pampau (northern Germany) are well known for their diverse assemblages of marine mammals, particularly whales. Despite numerous systematic and biostratigraphic studies, an in-depth palaeoecological analysis of its diverse molluscan assemblages and a comprehensive palaeoenvironmental reconstruction are lacking. Here, we integrated new faunal, sedimentological, and geochemical data to reconstruct the marine palaeo-ecosystem of the late Miocene sedimentary succession of Groß Pampau, and to identify the drivers controlling the composition, ecological structure and temporal dynamics of its macrobenthic molluscan assemblages. Fossil evidence, coupled with analyses of clay mineral composition, grain size distribution, and geochemical data (total organic carbon, total nitrogen, δ<sup>13</sup>C, δ<sup>18</sup>O, δ<sup>15</sup>N of sediment and shells), suggest a warm-temperate, mesotrophic, low-energy, offshore marine setting mostly below storm wave base and a pronounced surface-to-bottom water temperature gradient. Low variability in sedimentological and geochemical signals indicates generally stable physico-chemical conditions, whereas occurrences of opportunistic species (<em>Varicorbula</em> <em>gibba</em>) point at </span><span>occasionally less favourable bottom conditions, possibly related to transient hypoxia</span><span>. Canonical correspondence analysis reveals that the distribution of molluscan assemblages correlates with total organic carbon and nitrogen content, suggesting organic matter availability at the seafloor as a controlling factor. A pattern of repetitive punctuated stasis of molluscan assemblages is defined by the temporal persistence in taxonomic and ecological composition, occasionally interrupted by shifts to a different faunal configuration. We suggest that both stable environmental conditions and biotic interactions, i.e. the top-down control exerted by carnivorous gastropods and environmental modification by ubiquitous burrowing deposit feeders, probably contributed to the observed temporal stability. Whereas comparison with Miocene molluscan assemblages of Gram, Denmark, revealed differences in the presence and relative abundance of genera, functional congruence indicates that offshore benthic ecosystems of the southern North Sea Basin functioned similarly.</span></p>
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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.
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.