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1,047 results for “constraint”
Data for: Environmental and anthropogenic constraints on animal space use drive extinction risk worldwide
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Data from: Constraints on geographic variation in fiddler crabs (Ocypodidae: Uca) from the western Atlantic
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Analyzing time-energy constraints to understand the links between environmental change and local extinctions in terrestrial ectotherms
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The geometry of resource constraint: an empirical study of the golden snub-nosed monkey
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Multiplex networks reveal geographic constraints on illicit wildlife trafficking
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Dataset for: Physics-informed neural networks with monotonicity constraints for Richardson-Richards equation: Estimation of constitutive relationships and soil water flux density from volumetric water content measurements by Toshiyuki Bandai and Teamrat A. Ghezzehei
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Food availability, energetic constraints, and reproductive development in a wild bird: Central Arizona Phoenix
For many animals, the seasonal timing (phenology) of gonad cycles is an important adaptation to local environmental conditions. The available evidence suggests that birds adjust to urban areas by advancing the phenology of vernal gonad growth. To test whether the habitat-related disparity in gonad growth phenology is due to energetic constraints, we measured energetic status (i.e., body condition and fat stores) and hypothalamic levels of neuropeptide Y (NPY, a neuropeptide that potentially links food abundance to reproductive endocrine activity) of urban and desert Abert’s Towhees, Melozone aberti. To shed light on the physiological mechanism underlying variation in gonad growth phenology, we compared the (neuro)endocrine activity of the reproductive system at the hypothalamic (gonadotropin -releasing hormone [GnRH] and -inhibitory hormone [GnIH]) and gonadal (baseline plasma testosterone [T] and ‘GnRH challenge’-induced) levels, as well as the morphology dependent on these processes (paired testes mass, seminiferous tubule diameter, and cloacal protuberance width).
Data from: Fine-scale substrate heterogeneity in green roof plant communities: the constraint of size
Heterogeneity-diversity relationship (HDR) is commonly shown to be positive in accordance with classic niche processes. However, recent soil-based studies have often found neutral and even negative HDRs. Some of the suggested reasons for this discrepancy include the lack of resemblance between manipulated substrate and natural settings, the treated areas not being large enough to contain species' root span and finally limited-sized plots may not sustain focal species' populations over time. V egetated green roofs are a growing phenomenon in many cities that could be an ideal testing ground for this problem. Recent studies have focused on the ability of these roofs to sustain stable and diverse plant communities and substrate heterogeneity that would increase niches on the roof has been proposed as a method to attain this goal. We constructed an experimental design using green roof experimental modules (4 m²) where we manipulated mineral and organic substrate component heterogeneity in different subplots (0.25 m²) within the experimental module while maintaining the total sum of mineral and organic components. A local annual plant community was seeded in the modules and monitored over three growing seasons. We found that plant diversity and biomass were not affected by experimentally created substrate heterogeneity. In addition, we found that different treatments, as well as specific subplot substrates, had an effect on plant community assemblages during the first year but not during the second and third years. Substrate heterogeneity levels were mostly unchanged over time. The inability to retain plant community composition over the years despite the maintenance of substrate differences supports the hypothesis that maintenance of diversity is constrained at these spatial scales by unfavorable dispersal and increased stochastic events as opposed to predictions of classic niche processes.
Data from: Using artificial intelligence classification of videos to examine the environmental, evolutionary and physiological constraints on provisioning behavior
<p>The use of artificial intelligence (AI) technologies can revolutionize how we approach data collection and analysis in behavioral ecology. One such example is in provisioning behavior. Parents of altricial species are selected to provide parental care (such as food provisioning) for their offspring, but there is substantial variation in the level of this care. Provisioning rate may be determined environmentally, by the physiological ability of parents and needs of nestlings, or by evolutionary incentives. We quantified provisioning rate in 20 purple martin (<i>Progne subis</i>) nests in the context of an experimental reduction of nest ectoparasites. 10 nests had a parasite reduction treatment, and 10 nests were controls. By using AI to automate the analysis of nest camera videos we were able to obtain nearly-continuous provisioning rate information at a high temporal resolution for the first half of the nestling period. We used random forest modeling to assess the factors determining provisioning rate and found evidence for environmental, evolutionary and physiological constraints and incentives on provisioning. Birds appeared to be environmentally limited in their provisioning in cool, wet conditions, especially later in the breeding season; but adjusted their provisioning according to the changing physiological needs of nestlings. We found evidence for a compensatory response to increased parasite load, in which parents increased provisioning to more heavily parasitized nests.</p>
Ecological and social constraints combine to promote evolution of non-breeding strategies in clownfish
<p><span>Individuals that forgo their own reproduction in animal societies represent an evolutionary paradox because it is not immediately apparent how natural selection can preserve the genes that underlie non-breeding strategies. Cooperative breeding theory provides a solution to the paradox: non-breeders benefit by helping relatives and/or inheriting breeding positions;<sup> </sup>non-breeders do not disperse to breed elsewhere because of ecological constraints. However, the question of why non-breeders do not contest to breed within their group has rarely been addressed. Here, we use a wild population of clownfish (<i>Amphiprion percula</i>), where non-breeders wait peacefully for years to inherit breeding positions, to show non-breeders will disperse when ecological constraints (risk of mortality during dispersal) are experimentally weakened. In addition, we show non-breeders will contest when social constraints (risk of eviction during contest) are experimentally relaxed. Our results show it is the combination of ecological and social constraints that promote the evolution of non-breeding strategies. The findings highlight parallels between, and potential for fruitful exchange between, cooperative breeding theory and economic bargaining theory: individuals will forgo their own reproduction and wait peacefully to inherit breeding positions (engage in cooperative options) when there are harsh ecological constraints (poor outside options) and harsh social constraints (poor inside options). </span></p>
Kinematic, Metamorphic and Age Constraints on the Miyar Thrust Zone: Implications for the Eohimalayan History of the High Himalayan Crystalline of NW India
<p>Table 1: Instrumental setup and operating conditions during the LA-ICP-MS analyses</p> <p>Table 2: U/Th-Pb Analytical Data</p> <p> </p>
Thermal constraints on energy balance, behavior, and spatial distribution of grizzly bears
<p>1. Heat dissipation limit theory posits that energy available for growth and reproduction in endotherms is limited by their ability to dissipate heat. In mammals, endogenous heat production increases markedly during gestation and lactation, and thus female mammals may be subject to greater thermal constraints on energy expenditure than males. Such constraints likely have important implications for behavior and population performance in a warming climate.</p> <p>2. We used a mechanistic simulation model based on first principles of heat and mass transfer to study thermal constraints on activity (both timing and intensity) of captive female grizzly bears (Ursus arctos) in current and future climate scenarios. We then quantified the relative importance of regulatory behaviors for maintaining heat balance using GPS telemetry locations of lactating versus non-lactating female bears from Yellowstone National Park, and assessed the degree to which costs of thermoregulation constrained the distribution of sampled bears in space and time.</p> <p>3. Lactating female bears benefitted considerably more from behavioral cooling mechanisms (e.g., partial submersion in cool water or bedding on cool substrate) than non-lactating females in our simulations; the availability of water for thermoregulation increased the number of hours during which lactating females could be active by up to 60% under current climatic conditions and by up to 43% in the future climate scenario. Moreover, even in the future climate scenario lactating bears were able to achieve heat balance 24 hrs/day by thermoregulating behaviorally when water was available to facilitate cooling.</p> <p>4. The most important predictor of female grizzly bear distribution in Yellowstone, regardless of reproductive status, was elevation. However, variables associated with the thermal environment occurred with greater frequency in rules for predicting the distribution of lactating than non-lactating female bears. </p> <p>5. Our results suggest that the costs of heat dissipation, which are modulated by climate, may impose constraints on the behavior and energetics of large endotherms like grizzly bears, and that access to water for cooling will likely be an increasingly important driver of grizzly bear distribution in Yellowstone as the climate continues to warm.</p>
Data from: Uneven sampling and the analysis of vocal performance constraints
Studies of trilled vocalizations provide a premiere illustration of how performance constraints shape the evolution of mating displays. In trill production, vocal tract mechanics impose a trade-off between syllable repetition rate and frequency bandwidth, with the trade-off most pronounced at higher values of both parameters. Available evidence suggests that trills that simultaneously maximize both traits are more threatening to males or more attractive to females, consistent with a history of sexual selection favoring high-performance trills. Here, we identify a sampling limitation that confounds the detection and description of performance trade-offs. We reassess 70 data sets (from 26 published studies) and show that sampling limitations afflict 63 of these to some degree. Traditional upper-bound regression, which does not control for sampling limitations, detects performance trade-offs in 33 data sets; yet when sampling limitations are controlled, performance trade-offs are detected in only 15. Sampling limitations therefore confound more than half of all performance trade-offs reported using the traditional method. An alternative method that circumvents this sampling limitation, which we explore here, is quantile regression. Our goal is not to question the presence of mechanical trade-offs on trill production but rather to reconsider how these trade-offs can be detected and characterized from acoustic data.
Data from: Empirical and theoretical study of Atelostomate (Echinoidea, Echinodermata) plate architecture: using graph analysis to reveal structural constraints
Describing patterns of connectivity among organs is essential for identifying anatomical homologies among taxa. It is also critical for revealing morphogenetic processes and the associated constraints that control the morphological diversification of clades. This is particularly relevant for studies of organisms with skeletons made of discrete elements such as arthropods, vertebrates, and echinoderms. Nonetheless, relatively few studies devoted to morphological disparity have considered connectivity patterns as a level of morphological organization or developed comparative frameworks with proper tools. Here, we analyze connectivity patterns among apical plates in Atelostomata, the most diversified clade among irregular echinoids. The clade comprises approximately 1600 fossil and Recent species (e.g., 25% of post-Paleozoic species of echinoids) and shows high levels of morphological disparity. Plate connectivity patterns were analyzed using tools and statistics of graph theory. To describe and explore the diversity of connectivity patterns among plates, we symbolized each pattern as a graph in which plates are coded as nodes that are connected pairwise by edges. We then generated a comparative framework as a morphospace of connections, in which the disparity of plate patterns observed in nature was mapped and analyzed. Main results show that apical plate patterns are both highly disparate between and within atelostomate groups and limited in number; overall, they also constitute small, compact, and simple structures compared to possible random patterns. Main traits of the evolution of apical plate patterns reveal the existence of strong morphogenetic constraints that are phylogenetically determined. In contrast, evolutionary radiations within atelostomates were accompanied by a clear increase in disparity, suggesting a release of some constraints at the origin of clades.
Data from: Morph-specific artificial selection reveals a constraint on the evolution of polyphenisms
Theory predicts that the evolution of polyphenic variation is facilitated where morphs are genetically uncoupled and free to evolve towards their phenotypic optima. However, the assumption that developmentally plastic morphs can evolve independently has not been tested directly. Using morph-specific artificial selection, we investigated correlated evolution between the sexes and male morphs of the bulb mite Rhizoglyphus echinopus. Large 'fighter' males have a thick and sharply terminating pair of legs used to kill rival males, while small 'scrambler' males have unmodified legs, and search for unguarded females, avoiding fights. We selected on the relative leg width of only the fighter male morph, tracked the evolutionary responses in fighters and the correlated evolutionary responses in scramblers and females that were untouched by direct selection. Fighters diverged in relative leg thickness after six generations; assaying scramblers and females at the ninth generation we observed correlated responses in relative leg width in both. Our results represent strong evidence for the evolution of intraspecific phenotypic diversity despite correlated evolution between morphs and sexes, challenging the idea that male morphs are genetically uncoupled and free to independen- tly respond to selection. We, therefore, question the perceived necessity for genetic independence in traits with extreme phenotypic plasticity.
Data from: Context-dependent sex allocation: constraints on the expression and evolution of maternal effects
Despite decades of research, whether vertebrates can and do adaptively adjust the sex ratio of their offspring is still highly debated. However, this may have resulted from the failure of empirical tests to identify large and predictable fitness returns to females from strategic adjustment. Here we test the effect of diet quality and maternal condition on facultative sex ratio adjustment in the color polymorphic Gouldian finch (Erythrura gouldiae), a species that exhibits extreme maternal allocation in response to severe and predictable (genetically-determined) fitness costs. On high quality diets, females produced a relatively equal sex ratio, but over-produced sons in poor dietary conditions. Despite the lack of sexual size dimorphism, nutritionally-stressed foster sons were healthier, grew faster, and were more likely to survive than daughters. Although these findings are in line with predictions from sex allocation theory, the extent of adjustment is considerably lower than previously reported for this species. Females therefore have strong facultative control over sex allocation, but the extent of adjustment is likely determined by the relative magnitude of fitness gains and the ability to reliably predict sex-specific benefits from environmental (versus genetic) variables. These findings may help explain the often inconsistent, weak or inconclusive empirical evidence for adaptive sex ratio adjustment in vertebrates.
Data from: Flexibility, variability and constraint in energy management strategies across vertebrate taxa revealed by long-term heart rate measurements
1) Animals are expected to be judicious in the use of the energy they gain due to the costs and limits associated with its intake. The management of energy expenditure (EE) exhibited by animals has previously been considered in terms of three patterns: the constrained, independent and performance patterns of energy management. These patterns can be interpreted by regressing daily EE against maintenance EE measured over extended periods. From the multiple studies on this topic, there is equivocal evidence about the existence of universal patterns in certain aspects of energy management. 2) The implicit assumption that animals exhibit specifically one of three discrete energy management patterns, and without variation, seems simplistic. We suggest that animals can exhibit gradations of different energy management patterns and that the exact pattern will fluctuate as their environmental context changes. 3) To investigate these ideas, and for possible large-scale patterns in energy management pattern, we analysed long-term heart rate data – a strong proxy for EE – across and within individuals in 16 species of birds, mammals, and fish. 4) Our analyses of 292 individuals representing 46 539 observation-days suggest that vertebrates typically exhibit predominantly the independent or performance energy patterns at the across-individual level, and that the pattern does not associate with taxonomic group. Within individuals, however, animals generally exhibit some degree of energy constraint. Together, these findings indicate that across diverse species, some individuals supply more energy to all aspects of their life than do others, however all individuals must trade-off deployment of their available energy between competing functions. This demonstrates that within-individual analyses are essential for interpretation of energy management patterns. 5) We also found that species do not necessarily exhibit a fixed energy management pattern but rather temporal variation in their energy management over the year. Animals' energy management exhibited stronger energy constraint during periods of higher EE, which typically coincided with clear and key life cycle events such as reproduction, suggesting an adaptive plasticity to respond to fluctuating energy demands.
Data from: Bypass of genetic constraints during mutator evolution to antibiotic resistance
Genetic constraints can block many mutational pathways to optimal genotypes in real fitness landscapes, yet the extent to which this can limit evolution remains to be determined. Interestingly, mutator bacteria elevate only specific types of mutations, and therefore could be very sensitive to genetic constraints. Testing this possibility is not only clinically relevant, but can also inform about the general impact of genetic constraints in adaptation. Here, we evolved 576 populations of two mutator and one wild-type Escherichia coli to doubling concentrations of the antibiotic cefotaxime. All strains carried TEM-1, a β-lactamase enzyme well known by its low availability of mutational pathways. Crucially, one of the mutators does not elevate any of the relevant first-step mutations known to improve cefatoximase activity. Despite this, both mutators displayed a similar ability to evolve more than 1000-fold resistance. Initial adaptation proceeded in parallel through general multi-drug resistance mechanisms. High-level resistance, in contrast, was achieved through divergent paths; with the a priori inferior mutator exploiting alternative mutational pathways in PBP3, the target of the antibiotic. These results have implications for mutator management in clinical infections and, more generally, illustrate that limits to natural selection in real organisms are alleviated by the existence of multiple loci contributing to fitness.
Data from: Repeated origin of three-dimensional leaf venation releases constraints on the evolution of succulence in plants
Succulent water storage is a prominent feature among plants adapted to arid zones, but we know little about how succulence evolves and how it is integrated into organs already tasked with multiple functions. Increased volume in succulent leaves, for example, may result in longer transport distances between veins and the cells that they supply, which in turn could negatively impact photosynthesis [1, 2, 3 and 4]. We quantified water storage [5] in a group of 83 closely related species to examine the evolutionary dynamics of succulence and leaf venation. In most leaves, vein density decreased with increasing succulence, resulting in significant increases in the path length of water from veins to evaporative surfaces. The most succulent leaves, however, had a distinct three-dimensional (3D) venation pattern, which evolved 11–12 times within this small lineage, likely via multiple developmental pathways. 3D venation "resets" internal leaf distances, maintaining moderate vein density in extremely succulent tissues and suggesting that the evolution of extreme succulence is constrained by the need to maintain an efficient leaf hydraulic system. The repeated evolution of 3D venation decouples leaf water storage from hydraulic path length, facilitating the evolutionary exploration of novel phenotypic space.
Data from: Meta-analysis indicates that oxidative stress is both a constraint on and a cost of growth
Oxidative stress (OS) as a proximate mechanism for life-history trade-offs is widespread in the literature. One such resource allocation trade-off involves growth rate, and theory suggests that OS might act as both a constraint on and a cost of growth, yet studies investigating this have produced conflicting results. Here, we use meta-analysis to investigate whether increased OS levels impact on growth (OS as a constraint on growth) and whether greater growth rates can increase OS (OS as a cost of growth). The role of OS as a constraint on growth was supported by the meta-analysis. Greater OS, in terms of either increased damage or reduced levels of antioxidants, was associated with reduced growth although the effect depended on the experimental manipulation used. Our results also support an oxidative cost of growth, at least in terms of increased oxidative damage, although faster growth was not associated with a change in antioxidant levels. These findings that OS can act as a constraint on growth support theoretical links between OS and animal life histories and provide evidence for a growth–self-maintenance trade-off. Furthermore, the apparent oxidative costs of growth imply individuals cannot alter this trade-off when faced with enhanced growth. We offer a starting platform for future research and recommend the use of oxidative damage biomarkers in nonlethal tissue to investigate the growth–OS relationship further.
ScienceDex guides
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These curated guides explain access requirements, typical timelines, costs, and reuse considerations for widely used research datasets.
Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.