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257 results for “composition changes”
Long-term changes in taxonomic and functional composition of European marine fish communities
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High buffering potential of winter wheat composite cross populations to rapidly changing environmental conditions
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Data from: Rapid climate change increases diversity and homogenizes composition of coastal fish at high latitudes
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Data from: Regulation of fatty acid composition related to ontogenetic changes and niche differentiation of a common aquatic consumer
<p>Fatty acids (FAs) are key nutrients for fitness which take part in multiple physiological processes over the ontogeny of organisms. Yet, we lack evidence on how FA nutrition mediates life-history trade-offs and ontogenetic niche shifts in natural populations. In a field study, we analyzed ontogenetic changes in the FAs of Eurasian perch (<i>Perca fluviatilis</i> L.), a widespread fish that goes through ontogenetic niche shifts and can have high individual niche specialization. Diet explained most of the variation in the FA composition of perch dorsal muscle over early ontogeny (28%), while the total length explained 23%, suggesting that perch significantly regulated FA composition over early ontogeny. Condition explained 1% of the remaining variation. 18:3n-3 (ALA) and 18:4n-3 (SDA) indicated planktivory; 18:1n-7, benthivory; and 22:6n-3 (DHA), piscivory in perch diet. Conversely, perch regulated long-chained polyunsaturated fatty acids (PUFAs), such as 20:5n-3 (EPA), 20:4n-6 (ARA) and 22:6n-3 (DHA) over ontogeny, emphasizing the role of such FAs in early growth and sexual maturation. Adult perch increasingly retained 16:1n-7 and 18:1n-9 suggesting higher energy storage in older perch. Furthermore, differences in DHA availability in diet correlated with intra-cohort differences in perch growth, potentially hindering the overall use of benthic resources and promoting earlier shifts to piscivory in littoral habitats. Overall, this study indicates that in addition to diet, internal regulation may be more important for FA composition than previously thought. Differences between FA needs and FA availability may lead to life-history trade-offs that affect the ecology of consumers, including their niche.</p>
Data from: Fire history and plant community composition outweigh decadal multi-factor global change as drivers of microbial composition in an annual grassland
Soil microbial communities regulate and respond to key biogeochemical cycles and influence plant community patterns. However, microbial communities also respond to disturbance events, motivating an assessment of the relative roles of decadal multi-factor global change, disturbance, and plant community structure on microbial community responses. We used high-throughput amplicon sequencing to characterize the diversity and composition of bacterial and fungal communities in bulk soil (0–7 cm) collected in 2014 from the Jasper Ridge Global Change Experiment, a full-factorial field experiment in which ambient and elevated levels of nitrogen deposition (+7 g N m-2 yr-1 calcium nitrate), CO2 concentration (+275 ppm), temperature (+1–2 ºC), and precipitation (+50% volume with +3 weeks duration) were applied to a California annual grassland from 1998 to 2014. We used linear mixed-effects modeling to test for the effects of global change on microbial diversity (observed richness, Shannon index). We also used generalized dissimilarity modeling (GDM) to study controls on compositional dissimilarity in fungal and bacterial communities. Bacterial community composition was best explained by exposure to fires in 2003 and 2011, whereas fungal community composition was best explained by plant community composition. The richness of fungi increased under elevated nitrogen deposition; bacterial diversity metrics decreased under warmer temperatures. Interactions between global change factors were statistically insignificant or weak. Synthesis. Our results indicate that even on decadal timescales, the effects of fire history and plant community composition on bacterial and fungal community composition, respectively, outweigh the effects of multi-factor global change. Furthermore, global change factors have mostly additive effects on microbial diversity patterns. Our results show that highly variable mediators such as fire history and plant community composition limit the generalizability of soil microbial responses to long-term global change.
Extinction-immigration dynamics lag behind environmental filtering in shaping the composition of tropical dry forests within a changing landscape
The impact of rapid habitat loss and fragmentation on biodiversity is a major issue. However, we still lack an integrative understanding of how these changes influence biodiversity dynamics over time. In this study, we investigate the effects of these changes in terms of both niche-based and neutral dynamics. We hypothesize that habitat loss has delayed effects on neutral immigration-extinction dynamics, while edge effects and environmental heterogeneity in habitat patches have rapid effects on niche-based dynamics. We analyzed taxonomic and functional composition of 100 tree communities in a tropical dry forest landscape of New-Caledonia subject to habitat loss and fragmentation. We designed an original, process-based simulation framework, and performed Approximate Bayesian Computation to infer the influence of niche-based and neutral processes. Then, we performed partial regressions to evaluate the relationships between inferred parameter values of communities and landscape metrics (distance to edge, patch area, and habitat amount around communities), derived from either recent or past (65 yrs ago) aerial photographs, while controlling for the effect of soil and topography. We found that landscape structure influences both environmental filtering and immigration. Immigration rate was positively related to past habitat amount surrounding communities. In contrast, environmental filtering was mostly affected by present landscape structure and mainly influenced by edge vicinity and topography. Our results highlight that landscape changes have contrasting spatio-temporal influences on niche-based and neutral assembly dynamics. First, landscape-level habitat loss and community isolation reduce immigration and increase demographic stochasticity, resulting in slow decline of local species diversity and extinction debt. Second, recent edge creation affects environmental filtering, incurring rapid changes in community composition by favoring species with edge-adapted strategies. Our study brings new insights about temporal impacts of landscape changes on biodiversity dynamics. We stress that landscape history critically influences these dynamics and should be taken into account in conservation policies.
Data from: Scale-dependent shifts in the species composition of flower visitors with changing floral density
Responses of flower-visiting animals to floral density can alter interactions between plants, influencing a variety of biological processes, including plant population dynamics and the evolution of flowering phenology. Many studies have found effects of floral or plant density on pollinator visitation rates at patch scales, but little is known about responses of flower visitors to floral densities at larger scales. Here, I present data from an observational field study in which I measured the effects of floral density on visitation to the annual composite Holocarpha virgata at both patch (4 m(2)) and site (12.6 ha) spatial scales. The species composition of flower visitors changed with floral density, and did so in different ways at the two scales. At the site scale, average floral density within patches of H. virgata or within patches of all summer-flowering species combined had a significant positive effect on per-flowerhead visitation by the long-horned bee Melissodes lupina and no significant effects on visitation by any other taxa. At the patch scale, per-flowerhead visitation by honeybees significantly increased whereas visitation by M. lupina often decreased with increasing floral density. For both species, responses to patch-scale floral density were strongest when site-scale floral density was high. The scale-dependence of flower visitor responses to floral density and the interactions between site- and patch-scale effects of floral density observed in this study underscore the importance of improving our understanding of pollinators' responses to floral density at population scales.
Data from: Long-term genetic monitoring reveals contrasting changes in the genetic composition of newly established populations of the intertidal snail Bembicium vittatum
Newly established populations are susceptible to founder events that reduce genetic variation. This may be counterbalanced by gene flow after populations become established or founders coming from genetically different populations. However, initial gains in genetic diversity may be short-lived if there is limited mixing between lineages and subsequent inbreeding or if one lineage sweeps to fixation through selection or genetic drift. Here, we report on the genetic changes taking place within two newly established populations of intertidal snail over a 15-year period (~ 10 generations). Each translocation was set up using multiple, genetically distinct source populations. Our data show that higher levels of variation in the translocated populations compared to the source populations were maintained over time for both nuclear (microsatellite) and mitochondrial genes. Small changes in allele and haplotype frequencies were observed in the source populations and in one of the translocated populations, but marked changes were evident in the other, where there was a dramatic shift towards the genetic make-up of one of the source populations. These genetic changes occurred despite relatively large numbers of founders (200- 374 adults) and no evidence of the population experiencing a severe reduction in effective population size. Our study shows that the genetic composition of newly established populations can vary greatly over time and that genetic outcomes can be highly variable, and significantly different to expectations, even when they are established using high numbers of individuals and involve source populations from the same geographic regions.
Data from: Twentieth-century changes in the genetic composition of Swedish field pea metapopulations
Landrace crops are formed by local adaptation, genetic drift and gene flow through seed exchange. In reverse, the study of genetic structure between landrace populations can reveal the effects of these forces over time. We present here the analysis of genetic diversity in 40 Swedish field pea (Pisum sativum L.) populations, either available as historical seed samples from the late nineteenth century or as extant gene bank accessions assembled in the late twentieth century. The historical material shows constant high levels of within-population diversity, whereas the extant accessions show varying, and overall lower, levels of within-population diversity. Structure and principal component analysis cluster most accessions, both extant and historical, in groups after geographical origin. County-wise analyses of the accessions show that the genetic diversity of the historical accessions is largely overlapping. In contrast, most extant accessions show signs of genetic drift. They harbor a subset of the alleles found in the historical accessions and are more differentiated from each other. These results reflect how, historically present metapopulations have been preserved during the twentieth century, although as genetically isolated populations.
Data from: Changes in Eocene plant diversity and composition of the vegetation: the lacustrine archive of Messel (Germany)
Based on high resolution palynological analysis of 680 samples from a core, short-term changes in plant diversity and floristic composition within the Paleogene greenhouse have been detected in the lacustrine succession of a Lower to Middle Eocene maar lake at Messel (Federal State of Hesse, Germany). The microfloristic data show that taxonomic diversity increased rapidly within some decades during recolonization of a volcanically devastated area around the lake. With the establishment of a climax vegetation at the end of recolonization the maximum in palynological diversity was reached in the crater area. During the following 640 Kyr the composition of the palynospectrum changed only gradually. However, different richness and evenness estimations show that alpha and gamma diversity decreased up to 35% which can be related to the establishment of an equilibrium stage within the climax vegetation that led to the dominance of an assemblage of self-replacing species. Nevertheless, time series analysis of alpha diversity changes within the climax vegetation reveals that orbitally controlled climate change of Milankovitch and Sub-Milanovitch order influenced the diversity of the vegetation resulting in a rise of beta diversity. Based on the composition of the vegetation and comparison to modern analogues our analysis now proves that Eocene paratropical plant diversity increased during periods of slightly higher temperature and precipitation. Therefore, both composition and diversity of the vegetation was highly susceptible to minor-scale short-term changes in climate even during equable greenhouse conditions.
Data from: Differential drivers of benthic foraminiferal and molluscan community composition from a multivariate record of Early Miocene environmental change
Climate changes are multivariate in nature, and disentangling the proximal drivers of biotic responses to paleoclimate events requires time series of multiple environmental proxies. We reconstruct a multivariate time series of local environmental change for the early Miocene Newport Member of the Astoria Formation (20.26–18 Ma), using proxies for temperature (δ18O), productivity (δ13C), organic carbon flux (Δδ13C), oxygenation (δ15N), and sedimentary grain size (% mud). Our data suggest increases in productivity and declines in oxygenation on the Oregon shelf during this interval of global warming. We evaluate the association of individual environmental factors, and combinations of factors, with changes in faunal composition observed in benthic foraminiferal and molluscan communities collected from the exact same sediments as the environmental data. The δ15N values are the most parsimonious correlates with major changes in foraminiferal composition, whereas molluscan composition is most closely related to δ13C values, suggesting that different components of the environment are influencing each group. When the proxies that have the best supported relationships with the faunal gradients are removed from the analyses to simulate the absence of those proxy data, significant relationships between the faunal gradients and the remaining environmental proxies can still be found. This suggests that environmental drivers can be incorrectly attributed to faunal changes when key proxy data are missing. Paleoecological studies of biotic response that test multiple environmental drivers for multiple taxonomic groups are powerful tools for identifying the ecological consequences of past warming events and the regional drivers of ecological changes.
Data from: Compositional turnover and ecological changes related to the waxing and waning of glaciers during the Late Paleozoic ice age in ice-proximal regions (Pennsylvanian, western Argentina)
The late Paleozoic ice age (LPIA) had a profound effect on the biota. Despite much research having been focused on paleotropical regions or global-scale analyses, regional ecological changes have seldom been studied in ice-proximal basins. Here, I study the compositional turnover and diversity structure across the main Carboniferous glacial event recorded in western Argentina and the subsequent nonglacial interval. Brachiopod and bivalve data from western Argentina suggest that the transition from glacial to nonglacial climates caused major compositional changes. Turnover, however, was not uniform across the bathymetric gradient, being higher in deep environments. Because extirpation was concentrated in brachiopods, but immigration was similar in both clades, the taxonomic structure of the region was significantly modified. Although regional hierarchical diversity structure and occupancy distributions remained stable, dissecting the analysis in brachiopods and bivalves underscores that both clades had different responses to climate change. Brachiopods, on the one hand, show stability in the diversity structure and a very slight decrease in occupancies of intermediate genera, while bivalves show an important rise in diversity, both at the environment and regional scale, and an increase in genera with intermediate occupancies. The bathymetric diversity gradient was also modified from hump shaped with maximum diversity in the deep subtidal to a linear gradient with maximum values toward the offshore. However, relative compositional differences within environments remained stable, with maximum values at intermediate depths both in glacial and nonglacial intervals. Moreover, local-scale coexistence between brachiopods and bivalves changed in the nonglacial interval, showing significant segregation, which indicates relevant modifications in community assembly dynamics. Results from western Argentina highlight the magnitude of regional-scale ecological changes during the LPIA in ice-proximal regions, suggesting that the waxing and waning of glaciers was able to cause regional taxonomic turnover and medium-scale ecological changes even during intervals of relative macroevolutionary quiescence.
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.
Fig. 2. Climogram showing average month temperature and rainfall from June 1996 in Aquatic Coleoptera In The Subtropical-Pampasic Ecotone (Argentina, Buenos Aires): Species Composition And Temporal Changes
Fig. 2. Climogram showing average month temperature and rainfall from June 1996 to July 1998 (Data from Estación Meteorológica La Plata, Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata).
Raw data for "Application of biological early warning systems in wastewater treatment plants: Introducing a promising approach to monitor changing wastewater composition"
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SI-B for "Application of biological early warning systems in wastewater treatment plants: Introducing a promising approach to monitor changing wastewater composition"
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Data from: Intraspecific trait changes have large impacts on community functional composition but do not affect ecosystem function
<p>1. Plant functional traits can provide a mechanistic understanding of community responses to global change and of community effects on ecosystem functions. Nitrogen enrichment typically shifts trait composition by promoting the dominance of acquisitive plants (high specific leaf area [SLA] and low leaf dry matter content [LDMC]), translating into high biomass production. Changes in mean trait values can be due to shifts in species identity, relative abundances and/or intraspecific trait values. However, we do not know the relative importance of these shifts in determining trait responses to environmental changes, or trait effects on ecosystem functioning, such as biomass production. </p> <p><br> 2. We quantified the relative importance of species composition, abundance and intraspecific shifts in driving variation in SLA and LDMC, and how these shifts affected above- and belowground biomass. We measured traits in a grassland experiment manipulating nitrogen fertilisation, plant species richness, foliar fungal pathogen removal and sown functional composition (slow vs. fast species). We fitted structural equation models to test the importance of abundance and intraspecific shifts in determining 1) responses of functional composition to treatments and 2) effects on above and belowground biomass.</p> <p> <br> 3. We found that species intraspecific shifts were as important as abundance shifts in determining change in functional composition (community weighted mean trait values), and even had large effects compared to substantial initial variation in sown trait composition. Intraspecific trait shifts resulted in convergence towards intermediate SLA in diverse communities; although convergence was reduced by nitrogen addition and enhanced by pathogen removal. In contrast, large intraspecific shifts in LDMC were not influenced by the treatments. However, despite large responses, intraspecific trait shifts had no effect on above or belowground biomass. Only interspecific trait variation affected functioning: belowground biomass was reduced by SLA and increased by LDMC, while aboveground biomass was increased by SLA. </p> <p><br> 4. Our results add to a growing body of literature showing large species intraspecific trait variation and emphasise the importance of using field sampled data to determine community functional composition. However, they also show that intraspecific variation does not necessarily affect ecosystem functioning and therefore response-effect trait relationships may differ between vs. within species.</p>
Changes in arthropod communities mediate the effects of landscape composition and farm management on pest control ecosystem services in organically managed strawberry crops
<p>Landscape composition and local diversification practices such as polyculture, cover cropping, and hedgerows may promote natural pest control by benefiting natural enemy communities on farms. Our study employs piecewise structural equation modeling (PSEM) to test causal hypotheses regarding the effects of landscape composition and local diversification practices on arthropod communities and pest control ecosystem services.</p> <p>We sampled 27 organic strawberry fields in California's Central Coast region in 2015 and 2016 (17 repeated between years) for a total of 37 distinct sites across years. The sites were selected along orthogonal gradients of landscape composition and local diversification practices. We also investigated the effects of two common pest management practices. At each site, we sampled arthropod communities using a hand-held vacuum and performed sentinel prey experiments using the pest species <em>Lygus hesperus</em> to estimate pest control levels.</p> <p>At the landscape scale, proportion woods increased natural enemy abundance; at the local scale, diversification practices increased natural enemy diversity.</p> <p>Insecticides and tractor vacuuming, aimed at controlling pests, were indirectly detrimental to pest control services. Both practices decreased natural enemy abundance, and while insecticides also decreased pest abundance, vacuuming did not.</p> <p>Natural enemy abundance and diversity increased pest control levels, while pest abundance had the opposite effect. The PSEM results confirmed our hypotheses that landscape and local effects on pest control are mediated through changes in arthropod communities.</p> <p><em><a>Synthesis </a>and applications</em>: At the landscape scale, higher proportions of woody habitat are associated with greater natural enemy abundance, which increases pest control levels. When promoting pest control ecosystem services is a policy goal, regional planners should prioritize the conservation and restoration of woodlands in agricultural landscapes. At the local scale, decisions of individual growers can impact pest control services. For many growers, adopting practices that promote on-farm plant diversity may be a feasible solution for increasing pest control levels while avoiding the environmental and economic costs imposed by insecticide application and tractor <a>vacuuming. </a></p> <div> <div> <div class="msocomtxt"> <p class="MsoCommentText"> </p> </div> </div> </div>
Chemical compositions data for "Space weathering of the Chang'e-5 lunar sample from a mid-high latitude region on the Moon"
<p>Data for “Space weathering of the Chang’e-5 lunar sample from a mid-high latitude region on the Moon”</p>
Fire exclusion changes belowground bud bank and bud-bearing organ composition jeopardizing open savanna resilience
<p>Dataset from the article: Bombo, A.B.; Appezzato-da-Glória, B.; Fidelis, A. (2022) Fire exclusion changes belowground bud bank and bud-bearing organ composition jeopardizing open savanna resilience. <em>Oecologia</em> DOI 10.1007/s00442-022-05172-1, Article type: Community ecology – original research.</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.