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6,335 results for “direct”
Data from: Maternal diet and age alter direct and indirect relationships between life history traits across multiple generations
1. Maternal age has important consequences for offspring fitness, with influences on size, development, and reproductive schedules. Such maternal age effects may be driven by differential provisioning of resources, yet little is known about the role of environmental supply of nutritional resources in mediating such effects. 2. We tested the influence of limiting nutritional resource, dietary phosphorus (P), on maternal age effects across multiple generations by examining the potential interactive effects of maternal nutrition and age on daughter and granddaughter life history traits in the freshwater crustacean <i>Daphnia pulicaria</i>. 3. Maternal age and diet had significant but contrasting effects on offspring life history. We did not observe any evidence that age effects on offspring life history are mediated by maternal diet. However, granddaughter growth and size at maturation were influenced by the interaction between grandmaternal age and diet, suggesting that the appearance of transgenerational effects of age and diet were delayed by one generation. 4. Because offspring life history is often linked directly and/or indirectly to life history variation in previous generations, we utilized structural equation modeling (SEM) to assess such direct or indirect relationships. 5. SEM revealed striking differences in the relationship between growth, development time, and fecundity both within and among generations, depending on the age and diet in the F0 generation. Interestingly, direct and persistent relationships between the F0 generation and the F2 generation are most prevalent when grandmothers are old and fed low P diets, and such relationships are largely driven by fecundity in the F0 generation. Additionally, indirect causal relationships between the F0 generation and F2 generation are most pronounced when grandmothers are young and fed low P diets or when grandmothers are old and fed high P diets. 6. Our results indicate that transgenerational effects of maternal age and environment persist across multiple generations, and vary between successive generations. Further, our examination of the interaction network between life history traits of each generation suggest that the mechanisms for such persistent transgenerational effects are highly dependent on maternal condition.
Data from: Direct and indirect transgenerational effects alter plant-herbivore interactions
Theory suggests that environmental effects with transgenerational consequences, including rapid evolution and maternal effects, may affect the outcome of ecological interactions. However, indirect effects occur when interactions between two species are altered by the presence of a third species, and make the consequences of transgenerational effects difficult to predict. We manipulated the presence of insect herbivores and the competitor Medicago polymorpha in replicated Lotus wrangelianus populations. After one generation, we used seeds from the surviving Lotus to initiate a reciprocal transplant experiment to measure how transgenerational effects altered ecological interactions between Lotus, Medicago, and insect herbivores. Herbivore leaf damage and Lotus fecundity were dependent on both parental and offspring environmental conditions. The presence of insect herbivores or Medicago in the parental environment resulted in transgenerational changes in herbivore resistance, but these effects were non-additive, as a result of indirect effects in the parental environment. Indirect transgenerational effects interacted with more immediate ecological indirect effects on Lotus fecundity. These results suggest that explanations of ecological patterns require an understanding of transgenerational effects and that these effects may be difficult to predict in species-rich, natural communities where indirect effects are prevalent.
Disentangling direct and indirect effects of habitat fragmentation on wild plants' pollinator visits and seed production
<p>Habitat fragmentation threatens plant and pollinator communities, as well as their interactions. However, the effects of landscape fragmentation on the pollination of wild plant species are not well-understood yet, partly because in fragmented landscapes there are many correlated features (e.g. decreased patch size, increased isolation and patch complexity) whose influences are difficult to disentangle. Using a SEM approach, we assessed the direct and indirect effects of landscape fragmentation (patch size, isolation and complexity, percentage of surrounding forest) on the abundance, functional-group richness and evenness of pollinators of 24 habitat fragments within an agricultural landscape in Southern Norway. In addition, we studied how these variables affected visitation rates (visits/flower) and seed production (seed set, seed weight) in the four most abundant plant species in the area. Flower abundance was higher in larger and complex patches and decreased with the percentage of forest in the surroundings, while flower richness increased with patch complexity. We found a direct negative relationship between patch complexity and the overall number of pollinator visits that the habitat fragments received. Apart from this direct landscape effect, pollinator visits were mostly affected by the floral communities, with overall flower abundance and richness increasing both total number of pollinator visits and pollinator-group richness, and flower richness having an additional negative influence on pollinator-group evenness. Interestingly, we did not find any direct link between visitation rates and reproductive success for any of the study plant species. Instead, several landscape variables directly affected species seed production, although the effects of landscape on seed production were highly species-specific. Patch complexity, had a negative effect on seed production in two of the four focal species, while other components of the landscape had species-specific effects. Increasing fragmentation of agricultural landscapes affects pollination interactions at the community level and the reproduction of wild plants. However, understanding the effects of fragmentation on seed production requires going beyond estimating visitation rates, since landscape effects on plant reproduction are not always related to overall interaction frequencies.</p>
Data from: Direct detection of male quality can facilitate the evolution of female choosiness and indicators of good genes: evolution across a continuum of indicator mechanisms
The evolution of mating displays as indicators of male quality has been the subject of extensive theoretical and empirical research for over four decades. Research has also addressed the evolution of female mate choice favoring such indicators. Yet, much debate still exists about whether displays can evolve through the indirect benefits of female mate choice. Here, we use a population genetic model to investigate how the extent to which females can directly detect male quality influences the evolution of female choosiness and male displays. We use a continuum framework that incorporates indicator mechanisms that are traditionally modelled separately. Counter to intuition, we find that intermediate levels of direct detection of male quality can facilitate, rather than impede, the evolution of female choosiness and male displays in broad regions of this continuum. We examine how this evolution is driven by selective forces on genetic quality and on the display, and find that direct detection of male quality results in stronger indirect selection favoring female choosiness. Our results imply that displays maybe more likely to evolve when female choosiness has already evolved to discriminate perceptible forms of male quality. They also highlight the importance of considering general female choosiness, as well as preference, in studies of "good genes".
Data from: Adaptive developmental plasticity in a butterfly: mechanisms for size and time at pupation differ between diapause and direct development
Diapause (overwintering) and direct development are alternative developmental pathways in temperate insects. Diapause necessitates physiological preparations for dormancy, while direct development is associated with strong time constraints, resulting in selection for fast development under the direct development pathway. Physiological and behavioural preparations for pupation contribute to development time, so divergent selection in them is expected between the alternative developmental pathways. Critical mass for pupation induction is a central physiological parameter for the pupation process. Here, we compare the critical masses and the characteristics of the wandering stage – wandering taking place after the cessation of growth and before pupation – between diapausing and directly developing larvae in the butterfly Pieris napi. Critical mass estimation succeeded only for diapausing individuals, among which it was lower in females than in males, indicating an inter-pathway difference in the physiology of critical mass. Directly developing individuals wandered for a shorter time and distance and lost less mass before pupation than diapausing individuals. These physiological and behavioural differences represent adaptive phenotypic plasticity and contribute to fast development under direct development. Thus, the observed developmental plasticity in physiology offers a mechanistic explanation for adaptive life-history variation between alternative developmental pathways and sexual dimorphism.
Data from: Nest inheritance is the missing source of direct fitness in a primitively eusocial insect
Animals that co-operate with non-relatives represent a challenge to inclusive fitness theory, unless co-operative behavior is shown to provide direct fitness benefits. Inheritance of breeding resources could provide such benefits, but this route to co-operation has been little investigated in the social insects. We show that nest inheritance can explain the presence of unrelated helpers in a classic social insect model, the primitively eusocial wasp Polistes dominulus. We found that subordinate helpers produced more direct offspring than lone breeders, some while still subordinate but most after inheriting the dominant position. Thus, while indirect fitness obtained through helping relatives has been the dominant paradigm for understanding eusociality in insects, direct fitness is vital to explain co-operation in P. dominulus.
Direct and indirect effects of noise pollution alter biological communities in and near noise-exposed environments
<p>Noise pollution is pervasive across every ecosystem on Earth. Although decades of research have documented a variety of negative impacts of noise to organisms, key gaps remain, such as how noise affects different taxa within a biological community and how effects of noise propagate across space. We experimentally applied traffic noise pollution to multiple roadless areas and quantified the impacts of noise on birds, grasshoppers, and odonates. We show that acoustically-oriented birds have reduced species richness and abundance and different community compositions in experimentally noise-exposed areas relative to comparable quiet locations. We also found both acoustically-oriented grasshoppers and odonates without acoustic receptors to have reduced species richness and/or abundance in relatively quiet areas that abut noise-exposed areas. These results suggest that noise pollution not only affects acoustically-oriented animals, but that noise may reverberate through biological communities through indirect effects to those with no clear links to the acoustic realm, even in adjacent quiet environments.</p>
Data from: Direct evidence that density-dependent regulation underpins the temporal stability of abundant species in a diverse animal community
To understand how ecosystems are structured and stabilized, and to identify when communities are at risk of damage or collapse, we need to know how the abundances of the taxa in the entire assemblage vary over ecologically meaningful timescales. Here, we present an analysis of species temporal variability within a single large vertebrate community. Using an exceptionally complete 33-year monthly time series following the dynamics of 81 species of fishes, we show that the most abundant species are least variable in terms of temporal biomass, because they are under density-dependent (negative feedback) regulation. At the other extreme, a relatively large number of low abundance transient species exhibit the greatest population variability. The high stability of the consistently common high abundance species—a result of density-dependence—is reflected in the observation that they consistently represent over 98% of total fish biomass. This leads to steady ecosystem nutrient and energy flux irrespective of the changes in species number and abundance among the large number of low abundance transient species. While the density-dependence of the core species ensures stability under the existing environmental regime, the pool of transient species may support long-term stability by replacing core species should environmental conditions change.
Data from: Induced defences alter the strength and direction of natural selection on reproductive traits in common milkweed
Evolutionary biologists have long sought to understand the ecological processes that generate plant reproductive diversity. Recent evidence indicates that constitutive antiherbivore defences can alter natural selection on reproductive traits, but it is unclear whether induced defences will have the same effect and whether reduced foliar damage in defended plants is the cause of this pattern. In a factorial field experiment using common milkweed, Asclepias syriaca L., we induced plant defences using jasmonic acid (JA) and imposed foliar damage using scissors. We found that JA-induced plants experienced selection for more inflorescences that were smaller in size (fewer flowers), whereas control plants only experienced a trend towards selection for larger inflorescences (more flowers); all effects were independent of foliar damage. Our results demonstrate that induced defences can alter both the strength and direction of selection on reproductive traits, and suggest that antiherbivore defences may promote the evolution of plant reproductive diversity.
Data from: Directional reflectance and milli-scale feather morphology of the African Emerald Cuckoo, Chrysococcyx cupreus
Diverse plumages have evolved among birds through complex morphological modifications. We investigate how the interplay of light with surface and subsurface feather morphology determines the direction of light propagation, an understudied aspect of avian visual signalling. We hypothesize that milli-scale modifications of feathers produce anisotropic reflectance, the direction of which may be predicted by the orientation of the milli-scale structure. The subject of this study is the African Emerald Cuckoo, Chrysococcyx cupreus, noted for its shimmering green iridescent appearance. Using a spherical gantry, we measured the change in the directional reflectance across the feather surface and over a hemisphere of incident lighting directions. Using a microCT scanner, we also studied the morphology of the structural branches of the barb. We tracked the changes in the directional reflectance to the orientation of the structural branches as observed in the CT data. We conclude that (i) the far-field signal of the feather consists of multiple specular components, each associated with a different structural branch and (ii) the direction of each specular component is correlated to the orientation of the corresponding structure.
Data from: Directional dispersal has not evolved during the cane toad invasion
1. The ability to disperse along a consistent compass heading strongly affects the rate and efficiency of an animal's displacement, and thus is under selection at the expanding edge of a biological invasion. 2. We used radiotelemetry to assess whether the dispersal direction of cane toads (Rhinella marina) changed as a function of time since invasion, by comparing (i) toads at a single site monitored annually for 10 years subsequent to toad arrival; (ii) toads collected from sites across the species' invaded range in Australia, and radiotracked at a common site; and (iii) the offspring of those transported toads that were reared in captivity under common-garden conditions. 3. The first of these data sets showed non-random directionality, indicating strong spatial sorting operating on this trait: toads moved in a north-westerly direction for the first 6 years post-invasion, but in random directions thereafter. Despite the evidence for trait sorting, no consistent directionality was seen in toads relocated from populations with different invasion histories nor in their offspring. Why do we see no evolutionary shifts? 4. Dispersal directionality of the offspring was not correlated with that of their parents, arguing against a genetic basis to this behavioural trait. Thus, while an expanding invasion front creates an evolutionary pressure for animals to move in a specific direction, evolution of this trait has not occurred in this system because directionality is not heritable. 5. The observed north-westerly movements of toads at the invasion front were due to simple density differentials: in the first few years, most toads arriving at our study site originated from earlier-colonized (and hence denser) populations to the south-east.
Data from: Nocturnal migratory songbirds adjust their travelling direction aloft: evidence from a radiotelemetry and radar study
In order to fully understand the orientation behaviour of migrating birds, it is important to understand when birds set their travel direction. Departure directions of migratory passerines leaving stopover sites are often assumed to reflect the birds' intended travel directions, but this assumption has not been critically tested. We used data from an automated radiotelemetry system and a tracking radar at Falsterbo peninsula, Sweden, to compare the initial orientation of departing songbirds (recorded by radiotelemetry) with the orientation of songbird migrants in climbing and level flight (recorded by radar). We found that the track directions of birds at high altitudes and in level flight were more concentrated than the directions of departing birds and birds in climbing flight, which indicates that the birds adjust their travelling direction once aloft. This was further supported by a wide scatter of vanishing bearings in a subsample of radio-tracked birds that later passed an offshore radio receiver station 50 km southeast of Falsterbo. Track directions seemed to be more affected by winds in climbing compared with level flights, which may be explained by birds not starting to partially compensate for wind drift until they have reached cruising altitudes.
Data from: Cooperative investment in public goods is kin directed in communal nests of social birds
The tragedy of the commons predicts social collapse when public goods are jointly exploited by individuals attempting to maximise their fitness at the expense of other social group members. However, animal societies have evolved many times despite this vulnerability to exploitation by selfish individuals. Kin selection offers a solution to this social dilemma, but in large social groups mean relatedness is often low. Sociable weavers (Philetairus socius) live in large colonies that share the benefits of a massive communal nest, which requires individual investment for construction and maintenance. Here, we show that despite low mean kinship within colonies, relatives are spatially and socially clustered and that nest-building males have higher local relatedness to other colony members than do non-building males. Alternative hypotheses received little support, so we conclude that the benefits of the public good are shared with kin and that cooperative investment is, despite the large size and low relatedness of these communities, kin-directed.
Data from: Case-oriented selection of investigation methods in direct access: A comparison between physiotherapy trainees at professional colleges and in bachelor's study courses
Objective: Direct access to physiotherapy services is currently discussed in Germany. Its introduction would mean that initial diagnoses must be made in physiotherapy practices as well. However, it was not yet investigated whether the current training in physiotherapy is sufficient for this, and whether there are differences between the training systems. This study aims to answer the question of whether trainees at the end of Bachelor's studies (BS) are more reliably able to assess the case-related suitability of examination methods than professional college students (FS). Methodology: Questionnaires were developed to assess the suitability of examination methods for diagnostic inquiries. All professional colleges and bachelor's study courses listed with the German Physiotherapy Association were asked to present the questionnaires to their final classes. Results: In 216 addressed professional colleges and 24 bachelor's study courses, the return rate was 9.26% for professional colleges and 33.33% for study courses. One hundred thirty-eight questionnaires from students in 8 study courses and 368 questionnaires from students at 20 professional colleges were evaluated. The mean of correct decisions in total (of max. 54) was 19.01 (BS) or 15.73 (FS); in structure-related and function-related examination methods (of max. 42), it was 17.22 (BS) and 14.8 (FS); in activity-related methods (of max. 12), it was 1.97 (BS) and 0.89 (FS). Out of a max. of 49 examination methods, 23.45 (BS) and 26.72 (FS) were stated as unknown. Conclusion: The university students made correct decisions on the suitability of examination methods significantly more frequently than the professional college students. However, the determined group difference is low. Overall, the results do not appear sufficient for direct access. Training would have to be adapted for this purpose.
Data from: First direct measurements of behavioural responses by Cuvier's beaked whales to mid-frequency active sonar
Most marine mammal strandings coincident with naval sonar exercises have involved Cuvier's beaked whales (Ziphius cavirostris). We recorded acoustic and animal movement data on two tagged Ziphius and obtained the first direct measurements of behavioural responses of this species to mid-frequency active (MFA) sonar signals. Each recording included a 30-minute playback (one 1.6-s simulated MFA sonar signal repeated every 25 s); one whale was also incidentally exposed to MFA sonar from distant naval exercises. Whales responded strongly to playbacks at low received levels (89-127 dB re1µPa): after ceasing normal fluking and echolocation, they swam rapidly, silently away, extending both dive duration and subsequent non-foraging interval. Distant sonar exercises (78-106 dB re 1 µPa) did not elicit such responses, suggesting that context may moderate reactions. The observed responses to playback occurred at received levels well below current regulatory thresholds; equivalent responses to operational sonars could elevate stranding risk and reduce foraging efficiency.
Data from: Comparing direct and indirect selfing rate estimates: when are population-structure estimates reliable?
The rate of self-fertilization (that is, selfing) is a key evolutionary parameter in hermaphroditic species, yet obtaining accurate estimates of selfing rates in natural populations can be technically challenging. Most published estimates are derived from population-level heterozygote deficiency (that is, FIS) or identity disequilibria (for example, the software RMES (robust multilocus estimate of selfing)). These indirect methods can be applied to population genetic survey data, whereas direct methods using progeny arrays require much larger data sets that are often difficult to collect in natural populations or even require captive breeding. Unfortunately, indirect methods rely on assumptions that can be problematic, such as negating biparental inbreeding, inbreeding disequilibrium and (for FIS) the presence of null alleles. The performance of indirect estimates against progeny-array estimates is still largely unknown. Here we used both direct progeny-array and indirect population-level methods to estimate the selfing rate in a single natural population of the simultaneously hermaphroditic freshwater snail Radix balthica throughout its reproductive lifespan using 10 highly polymorphic microsatellites. We found that even though progeny arrays (n=1034 field-collected embryos from 60 families) did not reveal a single selfed embryo, FIS-based selfing rates (n=316 adults) were significantly positive in all 6 sequential population samples. Including a locus with a high frequency of null alleles further biased FIS-based estimates. Conversely, RMES-based estimates were very similar to progeny-array estimates and proved insensitive to null alleles. The assumptions made by RMES were thus either met or irrelevant in this particular population, making RMES a valid, cost-efficient alternative to progeny arrays.
Data from: The contribution of host cell-directed vs. parasite-directed immunity to the disease and dynamics of malaria infections
<p>Hosts defend themselves against pathogens by mounting an immune response. Fully understanding the immune response as a driver of host disease and pathogen evolution requires a quantitative account of its impact on parasite population dynamics. Here, we use a data-driven modeling approach to quantify the birth and death processes underlying the dynamics of infections of the rodent malaria parasite, <span>Plasmodium chabaudi</span>, and the red blood cells (RBCs) it targets. We decompose the immune response into 3 components, each with a distinct effect on parasite and RBC vital rates, and quantify the relative contribution of each component to host disease and parasite density. Our analysis suggest that these components are deployed in a coordinated fashion to realize distinct resource-directed defense strategies that complement the killing of parasitized cells. Early in the infection, the host deploys a strategy reminiscent of siege and scorched-earth tactics, in which it both destroys RBCs and restricts their supply. Late in the infection, a "juvenilization" strategy, in which turnover of RBCs is accelerated, allows the host to recover from anemia while holding parasite proliferation at bay. By quantifying the impact of immunity on both parasite fitness and host disease. we reveal that phenomena often interpreted as immunopathology may in fact be beneficial to the host. Finally, we show that, across mice, the components of the host response are consistently related to each other, even when infections take qualitatively different trajectories. This suggests the existence of simple rules that govern the immune system's deployment.</p>
Data from: Repeated losses of PRDM9-directed recombination despite the conservation of PRDM9 across vertebrates
Studies of highly diverged species have revealed two mechanisms by which meiotic recombination is directed to the genome—through PRDM9 binding or by targeting promoter-like features—that lead to dramatically different evolutionary dynamics of hotspots. Here, we identify PRDM9 orthologs from genome and transcriptome data in 225 species. We find the complete PRDM9 ortholog across distantly related vertebrates but, despite this broad conservation, infer a minimum of six partial and three complete losses. Strikingly, taxa carrying the complete ortholog of PRDM9 are precisely those with rapid evolution of its predicted binding affinity, suggesting that all domains are necessary for directing recombination. Indeed, as we show, swordtail fish carrying only a partial but conserved ortholog share recombination properties with PRDM9 knock-outs.
Data from: Influence of gaze and directness of approach on the escape responses of the Indian rock lizard, Psammophilus dorsalis (Gray, 1831)
Animals often evaluate the degree of risk posed by a predator and respond accordingly. Since many predators orient their eyes towards prey while attacking, predator gaze and directness of approach could serve as conspicuous indicators of risk to prey. The ability to perceive these cues and discriminate between high and low predation risk should benefit prey species through both higher survival and decreased energy expenditure. We experimentally examined whether Indian rock lizards (Psammophilus dorsalis) can perceive these two indicators of predation risk by measuring the variation in their fleeing behaviour in response to type of gaze and approach by a human predator. Overall, we found that the gaze and approach of the predator influenced flight initiation distance, which also varied with attributes of the prey (i.e. size/sex and tail-raise behaviour). Flight initiation distance (FID) was 43% longer during direct approaches with direct gaze compared with tangential approaches with averted gaze. In further, exploratory, analyses, we found that FID was 23% shorter for adult male lizards than for female or young male (FYM) lizards. In addition, FYM lizards that showed a tail-raise display during approach had a 71% longer FID than those that did not. Our results suggest that multiple factors influence the decision to flee in animals. Further studies are needed to test the generality of these factors and to investigate the proximate mechanisms underlying flight decisions.
Genetics of quantitative traits with dominance under stabilizing and directional selection in partially selfing species
<p>Recurrent self-fertilization is thought to lead to reduced adaptive potential by decreasing the genetic diversity of populations, thus leading selfing lineages down an evolutionary 'blind alley'. Though well supported theoretically, empirical support for reduced adaptability in selfing species is limited. One limitation of classical theoretical models is that they assume pure additivity of the fitness-related traits that are under stabilizing selection, despite ample evidence that quantitative traits are subject to dominance. Here we relax this assumption and explore the effect of dominance on a fitness-related trait under stabilizing selection for populations that differ in selfing rates. By decomposing the genetic variance into additional components specific to inbred populations, we show that dominance components can explain a substantial part of the genetic variance of inbred populations. We also show that ignoring these components leads to an upward bias in the predicted response to selection. Finally, we show that when considering the effect of dominance, the short-term evolutionary potential of populations remains comparable across the entire gradient in outcrossing rates, and genetic associations can even make selfing populations more evolvable on the longer term, reconciling theoretical and empirical results.</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.