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15,542 results for “How long”
A long tail of truth and beauty: a simple rule of pattern formation explains symmetry, complexity and beauty in the peacock's tail
<p><span>Darwin's theory of sexual selection by female choice has become a standard explanation for exaggerated sexually dimorphic traits, such as the peacock's (<i>Pavo cristatus</i>) long tail. Eyespot beauty-based female choice requires genetic variation in female preference and the number of eyespots, as well as a genetic correlation between the two. However, little genetic variation has been documented in either of these traits in natural and feral peacock populations. We examined the anatomical plan underlying feather development and discovered that eyespot feather follicles originate in alternating rows of 10/11, which uniquely determines the train's feather complexity, bilateral symmetry, and eyespot arrangement and beauty. This pattern precludes intrinsic variation in eyespot number, resulting in a fixed number of total eyespots in fully mature individuals. Since number of eyespots and tail length are independent traits and function of the age of the animal, the only variation available in these trats is also function of age. We propose an alternate, male drive, hypothesis in which females choose males based on their overall dominance (size, vigour, call, courting), and beauty of the train may (or may not) be a factor in female choice but it cannot affect the train length. This hypothesis can explain all known results. </span></p>
Data from: Long-term effective population size dynamics of an intensively monitored vertebrate population
Long-term genetic data from intensively monitored natural populations are important for understanding how effective population sizes (Ne) can vary over time. We therefore genotyped 1622 common buzzard (Buteo buteo) chicks sampled over 12 consecutive years (2002–2013 inclusive) at 15 microsatellite loci. This data set allowed us to both compare single-sample with temporal approaches and explore temporal patterns in the effective number of parents that produced each cohort in relation to the observed population dynamics. We found reasonable consistency between linkage disequilibrium-based single-sample and temporal estimators, particularly during the latter half of the study, but no clear relationship between annual Ne estimates (hdy201667e1gif(239)1917) and census sizes. We also documented a 14-fold increase in hdy201667e2gif(239)1917 between 2008 and 2011, a period during which the census size doubled, probably reflecting a combination of higher adult survival and immigration from further afield. Our study thus reveals appreciable temporal heterogeneity in the effective population size of a natural vertebrate population, confirms the need for long-term studies and cautions against drawing conclusions from a single sample.
Data from: Ocean circulation model predicts high genetic structure in a long-lived pelagic developer
Understanding the movement of genes and individuals across marine seascapes is a long-standing challenge in marine ecology, and can inform our understanding of local adaptation, the persistence and movement of populations, and the spatial scale of effective management. Patterns of gene flow in the ocean are often inferred based on population genetic analyses coupled with knowledge of species' dispersive life histories. However, genetic structure is the result of time-integrated processes, and may not capture present-day connectivity between populations. Here we use a high-resolution oceanographic circulation model to predict larval dispersal along the complex coastline of western Canada that includes the transition between two well-studied zoogeographic provinces. We simulate dispersal in a benthic sea star with a 6-10 week pelagic larval phase, and test predictions of this model against previously observed genetic structure including a strong phylogeographic break within the zoogeographical transition zone. We also test predictions with new genetic sampling in a site within the phylogeographic break. We find that the coupled genetic and circulation model predicts the high degree of genetic structure observed in this species, despite its long pelagic duration. High genetic structure on this complex coastline can thus be explained through ocean circulation patterns which tend to retain passive larvae within 20 - 50 km of their parents, suggesting a necessity for close-knit design of Marine Protected Area networks.
Data from: Complex biotic interactions drive long-term vegetation dynamics in a subarctic ecosystem
Predicting impacts of global warming requires understanding of the extent to which plant biomass and production are controlled by bottom-up and top-down drivers. By annually monitoring community composition in grazed control plots and herbivore-free exclosures at an Arctic location for 15 years, we detected multiple biotic interactions. Regular rodent cycles acted as pulses driving synchronous fluctuations in the biomass of field-layer vegetation; reindeer influenced the biomass of taller shrubs, and the abundance of plant pathogenic fungi increased when densities of their host plants increased in exclosures. Two outbreaks of geometrid moths occurred during the study period, with contrasting effects on the field layer: one in 2004 had marginal effects, while one in 2012 severely reduced biomass in the control plots and eliminated biomass that had accumulated over 15 years in the exclosures. The latter was followed by a dramatic decline of the dominant understory dwarf-shrub Empetrum hermaphroditum, driven by an interaction between moth herbivory on top buds and leaves, and increased disease severity of a pathogenic fungus. We show that the climate has important direct and indirect effects on all these biotic interactions. We conclude that long time series are essential to identify key biotic interactions in ecosystems, since their importance will be influenced by climatic conditions, and that manipulative treatments are needed in order to obtain the mechanistic understanding needed for robust predictions of future ecosystem changes and their feedback effects.
Data from: A comparative study of ancient sedimentary DNA, pollen and macrofossils from permafrost sediments of northern Siberia reveals long-term vegetational stability
Although ancient DNA from sediments (sedaDNA) has been used to investigate past ecosystems, the approach has never been directly compared to the traditional methods of pollen and macrofossil analysis. We conducted a comparative survey of 18 ancient permafrost samples spanning the Late Pleistocene (46–12.5 thousand years ago), from the Taymyr Peninsula in northern Siberia. The results show that pollen, macrofossils and sedaDNA are complementary rather than overlapping, and in combination reveal more detailed information on plant palaeocommunities than can be achieved by each individual approach. SedaDNA and macrofossils share greater overlap in plant identifications than with pollen, suggesting that sedaDNA is local in origin. These two proxies also permit identification to lower taxonomic levels than pollen, enabling investigation of temporal changes in species composition and the determination of indicator species to describe environmental changes. Combining data from all three proxies, reveals an area continually dominated by a mosaic vegetation of tundra-steppe, pioneer and wet-indicator plants. Such vegetational stability is unexpected, given the severe climate changes taking place in the northern hemisphere during this time, with changes in average annual temperatures of > 22ºC. This may explain the abundance of ice-age mammals such as horse and bison in Taymyr Peninsula during the Pleistocene, and why it acted as a refugium for the last mainland woolly mammoth. Our finding reveals the benefits of combining sedaDNA, pollen and macrofossil for palaeovegetational reconstruction and add to the increasing evidence suggesting large areas of the northern hemisphere remained ecologically stable during the Late Pleistocene.
Data from: Host resistance, population structure and the long-term persistence of bubonic plague: contributions of a modelling approach in the Malagasy focus
Although bubonic plague is an endemic zoonosis in many countries around the world, the factors responsible for the persistence of this highly virulent disease remain poorly known. Classically, the endemic persistence of plague is suspected to be due to the coexistence of plague resistant and plague susceptible rodents in natural foci, and/or to a metapopulation structure of reservoirs. Here, we test separately the effect of each of these factors on the long-term persistence of plague. We analyse the dynamics and equilibria of a model of plague propagation, consistent with plague ecology in Madagascar, a major focus where this disease is endemic since the 1920s in central highlands. By combining deterministic and stochastic analyses of this model, and including sensitivity analyses, we show that (i) endemicity is favoured by intermediate host population sizes, (ii) in large host populations, the presence of resistant rats is sufficient to explain long-term persistence of plague, and (iii) the metapopulation structure of susceptible host populations alone can also account for plague endemicity, thanks to both subdivision and the subsequent reduction in the size of subpopulations, and extinction-recolonization dynamics of the disease. In the light of these results, we suggest scenarios to explain the localized presence of plague in Madagascar.
Data from: Reduced tillage, but not organic matter input, increased nematode diversity and food web stability in European long-term field experiments
Soil nematode communities and food web indices can inform about the complexity, nutrient flows and decomposition pathways of soil food webs, reflecting soil quality. Relative abundance of nematode feeding and life-history groups are used for calculating food web indices, i.e. maturity index (MI), enrichment index (EI), structure index (SI) and channel index (CI). Molecular methods to study nematode communities potentially offer advantages compared to traditional methods in terms of resolution, throughput, cost and time. In spite of such advantages, molecular data have not often been adopted so far to assess the effects of soil management on nematode communities and to calculate these food web indices. Here, we used high-throughput amplicon sequencing to investigate the effects of tillage (conventional vs reduced) and organic matter addition (low vs high) on nematode communities and food web indices in ten European long-term field experiments and we assessed the relationship between nematode communities and soil parameters. We found that nematode communities were more strongly affected by tillage than by organic matter addition. Compared to conventional tillage, reduced tillage increased nematode diversity (23% higher Shannon diversity index), nematode community stability (12% higher MI), structure (24% higher SI), and the fungal decomposition channel (59% higher CI), and also the number of herbivorous nematodes (70% higher). Total and labile organic carbon, available K and microbial parameters explained nematode community structure. Our findings show that nematode communities are sensitive indicators of soil quality and that molecular profiling of nematode communities has the potential to reveal the effects of soil management on soil quality.
Data from: Ant mutualism increases long-term growth and survival of a common Amazonian tree
How ecological context shapes mutualistic relationships remains poorly understood. We combined long-term tree census data with ant censuses in a permanent 25-ha Amazonian forest dynamics plot to evaluate the effect of the mutualistic ant Myrmelachista schumanni (Formicinae) on the growth and survival of the common Amazonian tree Duroia hirsuta (Rubiaceae), considering its interactions with tree growth, population structure, and habitat. We found that the mutualist ant more than doubled tree relative growth rates and increased odds of survival. However, host tree size and density of conspecific neighbors modified the effect of the ant. Smaller trees hosting the mutualist ant consistently grew faster when surrounded by higher densities of conspecifics, suggesting that the benefit to the tree outweighs any negative effects of high conspecific densities. Moreover, our findings suggest that the benefit afforded by the ant diminishes with plant age and also depends on the density of conspecific neighbors. We provide the first long-term large-scale evidence of how mutualism affects the population biology of an Amazonian tree species.
Data from: Linking oceanographic conditions, migratory schedules and foraging behaviour during the non‐breeding season to reproductive performance in a long‐lived seabird
1. Studies of the mechanisms underlying climate-induced population changes are critically needed to better understand and accurately predict population responses to climate change. Long-lived migratory species might be particularly vulnerable to climate change as they are constrained by different climate conditions and energetic requirements during the breeding and non-breeding seasons. Yet, most studies primarily focus on the breeding season of these species lifecycle. Environmental conditions experienced in the non-breeding season may have downstream effects on the other stages of the annual lifecycle. Not investigating such effects may potentially lead to erroneous inferences about population dynamics. 2. Combining demographic and tracking data collected between 2006 and 2013 at Kerguelen Island on a long-lived migratory seabird, the Black-Browed Albatross (Thalassarche melanophris), we investigated the links between sea surface temperature during the non-breeding season and behavioural and phenological traits (at-sea behaviour and migratory schedules) while accounting for different responses between birds of different sex and reproductive status (previously failed or successful breeders). We then explored if variation in the foraging behaviour and timing of spring migration influenced subsequent reproductive performance. 3. Our results showed that foraging activity and migratory schedules varied by both sex and reproductive status suggesting different energetic requirements and constraints among individuals. Higher sea surface temperatures during late winter, assumed to reflect poor winter conditions, were associated with an earlier departure from the wintering grounds and an extended pre-breeding period. However, an earlier spring migration and an earlier return to Kerguelen grounds were associated with a lower breeding success. 4. Our results highlighted that behaviour during some periods of the non-breeding season, particularly towards the end of the wintering period and the pre-breeding period had a significant effect on the subsequent reproductive success. Therefore, caution needs to be given to all stages of the annual cycle when predicting the influence of climate on population dynamics.
Data from: Long-lasting effects of logging on beetles in hollow oaks
There is growing evidence that biodiversity is important for ecosystem functions. Thus, identification of habitat requirements essential for current species richness and abundance to persist is crucial. Hollow oaks (Quercus spp.) are biodiversity hot spots for deadwood‐dependent insect species, and the main objective of this paper was to test the effect of habitat history and current habitat distribution at various spatial scales on the associated beetle community. We used a gradient spanning 40 km from the coast to inland areas reflecting historical logging intensity (later and lower intensities inland) through 500 years in Southern Norway, to investigate whether the historical variation in oak density is influencing the structure of beetle communities in hollow oaks today. We trapped beetles in 32 hollow oaks along this gradient in forested and seminatural landscapes over two summers. We found higher species richness and total abundance inland consistent with our expectation based on historic logging intensity. Scale‐specific environmental variables also affected the response; beetle abundances were controlled by local conditions, whereas beetle species richness responded to habitat on the landscape scale. This indicates that long time continuity as well as large areas of favorable habitat is necessary to maintain beetle species richness through time in these highly long‐lasting structures.
Data from: Nest fidelity is driven by multi-scale information in a long-lived seabird
Although the reproductive success of most organisms depends on factors acting at several spatial scales, little is known about how organisms are able to synthesize multi-scale information to optimize reproduction. Using longitudinal data from a long-lived seabird, Monteiro's storm-petrel, we show that average breeding success is strongly related to oceanic conditions at the population level, and we postulate that (i) individuals use proximal information (their own reproduction outcome in year t) to assess the qualities of their mate and nest and to decide to retain them or not in year t + 1; (ii) the intensity of these responses depends on the quality of the oceanic environment in year t, which affects the predictability of reproduction outcome in year t + 1. Our results confirm that mate and nest fidelities are higher following successful reproduction and that the relationship between the success of a given pair and subsequent nest fidelity is stronger in years with unfavourable oceanic conditions, suggesting that individuals rely on distant information to modulate their use of proximal information and adjust their breeding strategy.
Data from: Phylogeography of western Mediterranean Cymbalaria (Plantaginaceae) reveals two independent long-distance dispersals and entails new taxonomic circumscriptions
The Balearic Islands, Corsica and Sardinia (BCS) constitute biodiversity hotspots in the western Mediterranean Basin. Oligocene connections and long distance dispersal events have been suggested to cause presence of BCS shared endemic species. One of them is Cymbalaria aequitriloba, which, together with three additional species, constitute a polyploid clade endemic to BCS. Combining amplified fragment length polymorphism (AFLP) fingerprinting, plastid DNA sequences and morphometrics, we inferred the phylogeography of the group and evaluated the species' current taxonomic circumscriptions. Based on morphometric and AFLP data we propose a new circumscription for C. fragilis to additionally comprise a group of populations with intermediate morphological characters previously included in C. aequitriloba. Consequently, we suggest to change the IUCN category of C. fragilis from critically endangered (CR) to near threatened (NT). Both morphology and AFLP data support the current taxonomy of the single island endemics C. hepaticifolia and C. muelleri. The four species had a common origin in Corsica-Sardinia, and two long-distance dispersal events to the Balearic Islands were inferred. Finally, plastid DNA data suggest that interspecific gene flow took place where two species co-occur.
Characterizing long-range search behavior in Diptera using complex 3D virtual environments
<p>The exemplary search capabilities of flying insects have established them as one of the most diverse taxa on Earth. However, we still lack the fundamental ability to quantify, represent, and predict trajectories under natural contexts to understand search and its applications. For example, flying insects have evolved in complex multimodal 3D environments, but we do not yet understand which features of the natural world are used to locate distant objects. Here, we independently and dynamically manipulate 3D objects, airflow fields, and odor plumes in virtual reality over large spatial and temporal scales. We demonstrate that that flies make use of features such as foreground segmentation, perspective, motion parallax, and integration of multiple modalities to navigate to objects in a complex 3D landscape while in flight. We first show that tethered flying insects of multiple species navigate to virtual 3D objects. Using the apple fly, <i>Rhagoletis pomonella</i>, we then measure their reactive distance to objects and show that these flies<i> </i>use perspective and local parallax cues to distinguish and navigate to virtual objects of different sizes and distances. We also show that apple flies can orient in the absence of optic flow by using only directional airflow cues, and require simultaneous odor and directional airflow input for plume following to a host volatile blend. The elucidation of these features unlocks the opportunity to quantify parameters underlying insect behavior such as reactive space, optimal foraging, and dispersal, as well as develop strategies for pest management, pollination, robotics and search algorithms.</p>
Data from: Exploring the temporal variability of a food web using long-term biomonitoring data
Ecological communities are constantly being reshaped in the face of environmental change and anthropogenic pressures. Yet, how food webs change over time remains poorly understood. Food web science is characterized by a trade-off between complexity (in terms of the number of species and feeding links) and dynamics. Topological analysis can use complex, highly resolved empirical food web models to explore the architecture of feeding interactions but is limited to a static view, whereas ecosystem models can be dynamic but use highly aggregated food webs. Here, we explore the temporal dynamics of a highly resolved empirical food web over a time period of 18 years, using the German Bight fish and benthic epifauna community as our case study. We relied on long-term monitoring ecosystem surveys (from 1998 to 2015) to build a metaweb, i.e. the meta food web containing all species recorded over the time span of our study. We then combined time series of species abundances with topological network analysis to construct annual food web snapshots. We developed a new approach, "node-weighted" food web metrics by including species abundances to represent the temporal dynamics of food web structure, focusing on generality and vulnerability. Our results suggest that structural food web properties change through time; however, binary food web structural properties may not be as temporally variable as the underlying changes in species composition. Further, the node-weighted metrics enabled us to detect that food web structure was influenced by changes in species composition during the first half of the time series and more strongly by changes in species dominance during the second half. Our results demonstrate how ecosystem surveys can be used to monitor temporal changes in food web structure, which are important ecosystem indicators for building marine management and conservation plans.
Data from: Long-term stasis and short-term divergence in the phenotypes of microsnails on oceanic islands
Phenotypic divergence is often unrelated to genotypic divergence. An extreme example is rapid phenotypic differentiation despite genetic similarity. Another extreme is morphological stasis despite substantial genetic divergence. These opposite patterns have been viewed as reflecting opposite properties of the lineages. In this study, phenotypic radiation accompanied by both rapid divergence and long-term conservatism is documented in the inferred molecular phylogeny of the micro land snails Cavernacmella (Assimineidae) on the Ogasawara Islands. The populations of Cavernacmella on the Sekimon limestone outcrop of Hahajima Island showed marked divergence in shell morphology. Within this area, one lineage diversified into types with elongated turret shells, conical shells and flat disc-like shells without substantial genetic differentiation. Additionally, a co-occurring species with these types developed a much larger shell size. Moreover, a lineage adapted to live inside caves in this area. In contrast, populations in the other areas exhibited no morphological differences despite high genetic divergence among populations. Accordingly, the phenotypic evolution of Cavernacmella in Ogasawara is characterized by a pattern of long-term stasis and periodic bursts of change. This pattern suggests that even lineages with phenotypic conservatism could shift to an alternative state allowing rapid phenotypic divergence.
Fidelity to foraging sites after long migrations
1. Patterns of animal movement associated with foraging lie at the heart of many ecological studies and often animals face decisions of staying in an environment they know, versus relocating to new sites. 2. The lack of knowledge of new foraging sites means there is risk associated with a decision to relocate (e.g. poor foraging) as well as a potential benefit (e.g. improved foraging). 3. Using a unique long-term satellite tracking dataset for several sea turtle species, combined with capture-mark-recapture (CMR) data extending over 50 years, we show how, across species, individuals generally maintain tight fidelity to specific foraging sites after extended (up to almost 10,000 km) migration to and from distant breeding sites as well as across many decades. 4. Migrating individuals often travelled through suitable foraging areas en route to their "home" site and so extended their journeys to maintain foraging site fidelity. 5. We explore the likely mechanistic underpinnings of this trait, which is also seen in some migrating birds, and suggest that individuals will forgo areas of suitable forage encountered en route during migration when they have poor knowledge of the long-term suitability of those sites, making relocation to those sites risky. 05-Nov-2019
Data from: Centennial-long trends of lake browning show major effect of afforestation
Observations of increasing water color and organic carbon concentrations in lakes are widespread across the Northern Hemisphere. The drivers of these trends are debated. Declining atmospheric sulfur deposition has been put forward as an important underlying factor, since recovery from acidification enhances mobility of organic matter from surrounding soils. This would suggest that the current browning represents a return to a more natural state. This study explores historical lake data from Sweden—1935 to 2015—providing a unique opportunity to see how and why water color has varied during almost a century. The data shows that sulfur deposition has not been the primary driver of water color trends over this period. I propose that the observed browning is to a large extent driven by a major transition from agriculture to forestry.
Data from: The rediscovery of a long described species reveals additional complexity in speciation patterns of poeciliid fishes in sulfide springs
The process of ecological speciation drives the evolution of locally adapted and reproductively isolated populations in response to divergent natural selection. In Southern Mexico, several lineages of the freshwater fish species of the genus Poecilia have independently colonized toxic, hydrogen sulfide-rich springs. Even though ecological speciation processes are increasingly well understood in this system, aligning the taxonomy of these fish with evolutionary processes has lagged behind. While some sulfide spring populations are classified as ecotypes of Poecilia mexicana, others, like P. sulphuraria, have been described as highly endemic species. Our study particularly focused on elucidating the taxonomy of the long described sulfide spring endemic, Poecilia thermalis Steindachner 1863, and investigates if similar evolutionary patterns of phenotypic trait divergence and reproductive isolation are present as observed in other sulfidic species of Poecilia. We applied a geometric morphometric approach to assess body shape similarity to other sulfidic and non-sulfidic fish of the genus Poecilia. We also conducted phylogenetic and population genetic analyses to establish the phylogenetic relationships of P. thermalis and used a population genetic approach to determine levels of gene flow among Poecilia from sulfidic and non-sulfidic sites. Our results indicate that P. thermalis' body shape has evolved in convergence with other sulfide spring populations in the genus. Phylogenetic analyses placed P. thermalis as most closely related to one population of P. sulphuraria, and population genetic analyses demonstrated that P. thermalis is genetically isolated from both P. mexicana ecotypes and P. sulphuraria. Based on these findings, we make taxonomic recommendations for P. thermalis. Overall, our study verifies the role of hydrogen sulfide as a main factor shaping convergent, phenotypic evolution and the emergence of reproductive isolation between Poecilia populations residing in adjacent sulfidic and non-sulfidic environments.
Maya assignment 1 long sword
Source: Objaverse 1.0 / Sketchfab
Data Processing for a Small-Scale Long-Term Coastal Ocean Observing System Near Mobile Bay, Alabama: A Geoscience Papers of the Future (GPF) Data Set
<p>The Dauphin Island Sea Lab (DISL) has been operating a permanent moored oceanographic station at 30 05.410'N, 88 12.694'W, 25 km southwest of the entrance to Mobile Bay, Alabama, since 2004. It collects hydrographic and current velocity data.</p> <p>This set of data files was collected between 27 Jan and 18 May 2011. It includes the raw data at initial download from the instruments, several intermediate processing steps, and final processed files ready for initial scientific analysis.</p> <p>The files have been prepared as supplementary material for a Geoscience Paper of the Future (GPF) in prep for publication at Earth and Space Science, as part of the OntoSoft GPF Initiative.</p> <p> </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.