Balancing selection shapes density-dependent foraging behaviour.
Ontology highlight
ABSTRACT:
SUBMITTER: Greene JS
PROVIDER: S-EPMC5161598 | biostudies-literature | 2016 Nov
REPOSITORIES: biostudies-literature
Publications
Balancing selection shapes density-dependent foraging behaviour.
Greene Joshua S JS Brown Maximillian M Dobosiewicz May M Ishida Itzel G IG Macosko Evan Z EZ Zhang Xinxing X Butcher Rebecca A RA Cline Devin J DJ McGrath Patrick T PT Bargmann Cornelia I CI
Nature 20161031 7628
The optimal foraging strategy in a given environment depends on the number of competing individuals and their behavioural strategies. Little is known about the genes and neural circuits that integrate social information into foraging decisions. Here we show that ascaroside pheromones, small glycolipids that signal population density, suppress exploratory foraging in Caenorhabditis elegans, and that heritable variation in this behaviour generates alternative foraging strategies. We find that natu ...[more]
Similar Datasets
Project description:Grouping behaviour, as fascinating as it is unclear, has lately drawn the attention of numerous researchers. While most of the authors focused their work on a mechanistic approach to the matter of schooling, this study explores the issue from a population point of view. Present camera observation study on the fish community carried out in the epipelagic habitat of a European temperate reservoir in the Czech Republic explored the relationship between density and aggregative features of predominantly cyprinid fish stock. Results demonstrated that schooling behaviour is triggered by the 'critical density' of fish in the habitat. School size as well as counts of schools and proportion of schooling individuals increased with the density of fish. Counts of clusters (observed units in time, including singletons, pairs and schools) and cluster size, on the other hand, showed a slowing tendency to increase. The slower increase implies the tendency of fish for not being frequent but rather to create larger groups. Altogether, our findings suggest that fish density is a triggering factor in the formation of large fish schools. As the tendency of cyprinid species for school formation could be an evolutional advantage responsible for dominance in later succession phases of water bodies, we suggest that more in situ studies should be encouraged for the proper understanding of the ecological interactions that drive the structure of aquatic ecosystems and for ensuring unbiased assessment.
| S-EPMC6366398 | biostudies-literature
Project description:In vertebrate animals, genes of the major histocompatibility complex (MHC) determine the set of pathogens to which an individual's adaptive immune system can respond. MHC genes are extraordinarily polymorphic, often showing elevated nonsynonymous relative to synonymous sequence variation and sharing presumably ancient polymorphisms between lineages. These patterns likely reflect pathogen-mediated balancing selection, for example, rare-allele or heterozygote advantage. Such selection is often reinforced by disassortative mating at MHC. We characterized exon 2 of MHC class II, corresponding to the hypervariable peptide-binding region, in song sparrows (Melospiza melodia). We compared nonsynonymous to synonymous sequence variation in order to identify positively selected sites; assessed evidence for trans-species polymorphisms indicating ancient balancing selection; and compared MHC similarity of socially mated pairs to expectations under random mating. Six codons showed elevated ratios of nonsynonymous to synonymous variation, consistent with balancing selection, and we characterized several alleles similar to those occurring in at least four other avian families. Despite this evidence for historical balancing selection, mated pairs were significantly more similar at MHC than were randomly generated pairings. Nonrandom mating at MHC thus appears to partially counteract, not reinforce, pathogen-mediated balancing selection in this system. We suggest that in systems where individual fitness does not increase monotonically with MHC diversity, assortative mating may help to avoid excessive offspring heterozygosity that could otherwise arise from long-standing balancing selection.
| S-EPMC6509439 | biostudies-literature
Project description:Scratch assays are routinely used to study collective cell behaviour in vitro. Typical experimental protocols do not vary the initial density of cells, and typical mathematical modelling approaches describe cell motility and proliferation based on assumptions of linear diffusion and logistic growth. Jin et al. (Jin et al. 2016 J. Theor. Biol. 390, 136-145 (doi:10.1016/j.jtbi.2015.10.040)) find that the behaviour of cells in scratch assays is density-dependent, and show that standard modelling approaches cannot simultaneously describe data initiated across a range of initial densities. To address this limitation, we calibrate an individual-based model to scratch assay data across a large range of initial densities. Our model allows proliferation, motility, and a direction bias to depend on interactions between neighbouring cells. By considering a hierarchy of models where we systematically and sequentially remove interactions, we perform model selection analysis to identify the minimum interactions required for the model to simultaneously describe data across all initial densities. The calibrated model is able to match the experimental data across all densities using a single parameter distribution, and captures details about the spatial structure of cells. Our results provide strong evidence to suggest that motility is density-dependent in these experiments. On the other hand, we do not see the effect of crowding on proliferation in these experiments. These results are significant as they are precisely the opposite of the assumptions in standard continuum models, such as the Fisher-Kolmogorov equation and its generalizations.
| S-EPMC7211478 | biostudies-literature
Project description:Climate changes pose risks for bumblebee populations, which have declined relative to the growing frequency and severity of warmer temperature extremes. Bumblebees might mitigate the effects of such extreme weather through colonial behaviours. In particular, fanning behaviour to dissipate heat is an important mechanism that could reduce exposure of thermally sensitive offspring to detrimental nest temperatures (Tn). The allocation of workers towards fanning over prolonged periods could impact foraging activity that is essential for colony-sustaining resource gathering. Colony maintenance and growth could suffer as a result of nutritional and high ambient temperature (Ta) thermal stress. It remains uncertain whether a compromise occurs between thermoregulation and foraging under chronic, sublethal heat events and how colony success is impacted as a result. This study held colonies of Bombus impatiens at constant high Ta (25°C, 30°C or 35°C) for 2 weeks while quantifying the percentage of foragers, fanning incidence, nest temperature (Tn) and other metrics of colony success such as the percentage of adult emergence and offspring production. We found that foraging and adult emergence were not significantly affected by Ta, but that thermoregulation was unsuccessful at maintaining Tn despite increased fanning at 35°C. Furthermore, 35°C resulted in workers abandoning the colony and fewer offspring being produced. Our findings imply that heatwave events that exceed 30°C can negatively impact colony success through failed thermoregulation and reduced workforce production.
| S-EPMC10853005 | biostudies-literature
Project description:BackgroundThere is strong incentive to model behaviour-dependent habitat selection, as this can help delineate critical habitats for important life processes and reduce bias in model parameters. For this purpose, a two-stage modelling approach is often taken: (i) classify behaviours with a hidden Markov model (HMM), and (ii) fit a step selection function (SSF) to each subset of data. However, this approach does not properly account for the uncertainty in behavioural classification, nor does it allow states to depend on habitat selection. An alternative approach is to estimate both state switching and habitat selection in a single, integrated model called an HMM-SSF.MethodsWe build on this recent methodological work to make the HMM-SSF approach more efficient and general. We focus on writing the model as an HMM where the observation process is defined by an SSF, such that well-known inferential methods for HMMs can be used directly for parameter estimation and state classification. We extend the model to include covariates on the HMM transition probabilities, allowing for inferences into the temporal and individual-specific drivers of state switching. We demonstrate the method through an illustrative example of plains zebra (Equus quagga), including state estimation, and simulations to estimate a utilisation distribution.ResultsIn the zebra analysis, we identified two behavioural states, with clearly distinct patterns of movement and habitat selection ("encamped" and "exploratory"). In particular, although the zebra tended to prefer areas higher in grassland across both behavioural states, this selection was much stronger in the fast, directed exploratory state. We also found a clear diel cycle in behaviour, which indicated that zebras were more likely to be exploring in the morning and encamped in the evening.ConclusionsThis method can be used to analyse behaviour-specific habitat selection in a wide range of species and systems. A large suite of statistical extensions and tools developed for HMMs and SSFs can be applied directly to this integrated model, making it a very versatile framework to jointly learn about animal behaviour, habitat selection, and space use.
| S-EPMC10239607 | biostudies-literature
Project description:Anthropogenic elevation of atmospheric CO2 is driving global-scale ocean acidification, which consequently influences calcification rates of many marine invertebrates and potentially alters their susceptibility to predation. Ocean acidification may also impair an organism's ability to process environmental and biological cues. These counteracting impacts make it challenging to predict how acidification will alter species interactions and community structure. To examine effects of acidification on consumptive and behavioural interactions between mud crabs (Panopeus herbstii) and oysters (Crassostrea virginica), oysters were reared with and without caged crabs for 71 days at three pCO2 levels. During subsequent predation trials, acidification reduced prey consumption, handling time and duration of unsuccessful predation attempt. These negative effects of ocean acidification on crab foraging behaviour more than offset any benefit to crabs resulting from a reduction in the net rate of oyster calcification. These findings reveal that efforts to evaluate how acidification will alter marine food webs should include quantifying impacts on both calcification rates and animal behaviour.
| S-EPMC4590471 | biostudies-literature
Project description:In the context of climate change, how extreme climatic events, such as cyclones, will affect the foraging abilities of marine vertebrates is still poorly known. During the course of a study on the foraging behaviour of two tropical seabirds, red-footed boobies and great frigatebirds, several cyclones have affected their breeding grounds and foraging zones, allowing us to study their response to extreme wind conditions. We examined whether adults and young naïve birds were able to predict the arrival of a cyclone and behave accordingly to reduce mortality risks and optimise foraging. We show that when a cyclone approached, juveniles and adults of the two species differed in their decisions to leave the colony for the sea. When the winds reached gale force, the juveniles of both species and adult frigatebirds remained at the colony, whereas adult boobies continued their foraging routine. The mortality of the individuals remaining on land remained limited. When encountering at-sea gale conditions, adult birds were able to avoid the centre of the low pressure systems and moved westward to bypass the route of the cyclones and circumvent the moving cyclone. Frigatebirds climb to high altitudes when close to the eye of the cyclone to bypass it at high speeds. These movements likely reduce the mortality risk at sea but can temporarily cause birds to move outside their normal range at sea or over land masses. We discuss the potential consequences of an increase in cyclonic conditions on seabird populations.
| S-EPMC6443659 | biostudies-literature
Project description:Transport infrastructure elements are widespread and increasing in size and length in many countries, with the subsequent alteration of landscapes and wildlife communities. Nonetheless, their effects on habitat selection by raptors are still poorly understood. In this paper, we analyzed raptors' foraging habitat selection in response to conventional roads and high capacity motorways at the landscape scale, and compared their effects with those of other variables, such as habitat structure, food availability, and presence of potential interspecific competitors. We also analyzed whether the raptors' response towards infrastructure depends on the spatial scale of observation, comparing the attraction or avoidance behavior of the species at the landscape scale with the response of individuals observed in the proximity of the infrastructure. Based on ecological hypotheses for foraging habitat selection, we built generalized linear mixed models, selected the best models according to Akaike Information Criterion and assessed variable importance by Akaike weights. At the community level, the traffic volume was the most relevant variable in the landscape for foraging habitat selection. Abundance, richness, and diversity values reached their maximum at medium traffic volumes and decreased at highest traffic volumes. Individual species showed different degrees of tolerance toward traffic, from higher abundance in areas with high traffic values to avoidance of it. Medium-sized opportunistic raptors increased their abundance near the traffic infrastructures, large scavenger raptors avoided areas with higher traffic values, and other species showed no direct response to traffic but to the presence of prey. Finally, our cross-scale analysis revealed that the effect of transport infrastructures on the behavior of some species might be detectable only at a broad scale. Also, food availability may attract raptor species to risky areas such as motorways.
| S-EPMC4365038 | biostudies-literature
Project description:Oxytocin is important for social interactions and maternal behaviour. However, little is known about when, where and how oxytocin modulates neural circuits to improve social cognition. Here we show how oxytocin enables pup retrieval behaviour in female mice by enhancing auditory cortical pup call responses. Retrieval behaviour required the left but not right auditory cortex, was accelerated by oxytocin in the left auditory cortex, and oxytocin receptors were preferentially expressed in the left auditory cortex. Neural responses to pup calls were lateralized, with co-tuned and temporally precise excitatory and inhibitory responses in the left cortex of maternal but not pup-naive adults. Finally, pairing calls with oxytocin enhanced responses by balancing the magnitude and timing of inhibition with excitation. Our results describe fundamental synaptic mechanisms by which oxytocin increases the salience of acoustic social stimuli. Furthermore, oxytocin-induced plasticity provides a biological basis for lateralization of auditory cortical processing.
| S-EPMC4409554 | biostudies-literature
Project description:Density-dependent competition for food resources influences both foraging ecology and reproduction in a variety of animals. The relationship between colony size, local prey depletion, and reproductive output in colonial central-place foragers has been extensively studied in seabirds; however, most studies have focused on effects of intraspecific competition during the breeding season, while little is known about whether density-dependent resource depletion influences individual migratory behavior outside the breeding season. Using breeding colony size as a surrogate for intraspecific resource competition, we tested for effects of colony size on breeding home range, nestling health, and migratory patterns of a nearshore colonial seabird, the brown pelican (Pelecanus occidentalis), originating from seven breeding colonies of varying sizes in the subtropical northern Gulf of Mexico. We found evidence for density-dependent effects on foraging behavior during the breeding season, as individual foraging areas increased linearly with the number of breeding pairs per colony. Contrary to our predictions, however, nestlings from more numerous colonies with larger foraging ranges did not experience either decreased condition or increased stress. During nonbreeding, individuals from larger colonies were more likely to migrate, and traveled longer distances, than individuals from smaller colonies, indicating that the influence of density-dependent effects on distribution persists into the nonbreeding period. We also found significant effects of individual physical condition, particularly body size, on migratory behavior, which in combination with colony size suggesting that dominant individuals remain closer to breeding sites during winter. We conclude that density-dependent competition may be an important driver of both the extent of foraging ranges and the degree of migration exhibited by brown pelicans. However, the effects of density-dependent competition on breeding success and population regulation remain uncertain in this system.
| S-EPMC5574757 | biostudies-literature