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13,017 results for “Positionning”
Data from: Comparative genomics of chemosensory protein genes reveals rapid evolution and positive selection in ant-specific duplicates
Gene duplications can have a major role in adaptation, and gene families underlying chemosensation are particularly interesting due to their essential role in chemical recognition of mates, predators and food resources. Social insects add yet another dimension to the study of chemosensory genomics, as the key components of their social life rely on chemical communication. Still, chemosensory gene families are little studied in social insects. Here we annotated chemosensory protein (CSP) genes from seven ant genomes and studied their evolution. The number of functional CSP genes ranges from 11 to 21 depending on species, and the estimated rates of gene birth and death indicate high turnover of genes. Ant CSP genes include seven conservative orthologous groups present in all the ants, and a group of genes that has expanded independently in different ant lineages. Interestingly, the expanded group of genes has a differing mode of evolution from the orthologous groups. The expanded group shows rapid evolution as indicated by a high dN/dS (nonsynonymous to synonymous changes) ratio, several sites under positive selection and many pseudogenes, whereas the genes in the seven orthologous groups evolve slowly under purifying selection and include only one pseudogene. These results show that adaptive changes have played a role in ant CSP evolution. The expanded group of ant-specific genes is phylogenetically close to a conservative orthologous group CSP7, which includes genes known to be involved in ant nestmate recognition, raising an interesting possibility that the expanded CSPs function in ant chemical communication.
Data from: Gliding lizards use the position of the sun to enhance social display
Effective communication requires animal signals to be readily detected by receivers in the environments in which they are typically given. Certain light conditions enhance the visibility of colour signals and these conditions can vary depending on the orientation of the sun and the position of the signaller. We tested whether Draco sumatranus gliding lizards modified their position relative to the sun to enhance the conspicuousness of their throat-fan (dewlap) during social display to conspecifics. The dewlap was translucent, and we found that lizards were significantly more likely to orient themselves perpendicular to the sun when displaying. This increases the dewlap's radiance, and likely, its conspicuousness, by increasing the amount of light transmitted through the ornament. This is a rare example of a behavioural adaptation for enhancing the visibility of an ornament to distant receivers.
Data from: Magnitude and sign epistasis among deleterious mutations in a positive-sense plant RNA virus
How epistatic interactions between mutations determine the genetic architecture of fitness is of central importance in evolution. The study of epistasis is particularly interesting for RNA viruses because of their genomic compactness, lack of genetic redundancy, and apparent low complexity. Moreover, interactions between mutations in viral genomes determine traits such as resistance to antiviral drugs, virulence and host range. In this study we generated 53 Tobacco etch potyvirus genotypes carrying pairs of single-nucleotide substitutions and measured their separated and combined deleterious fitness effects. We found that up to 38% of pairs had significant epistasis for fitness, including both positive and negative deviations from the null hypothesis of multiplicative effects. Interestingly, the sign of epistasis was correlated with viral protein–protein interactions in a model network, being predominantly positive between linked pairs of proteins and negative between unlinked ones. Furthermore, 55% of significant interactions were cases of reciprocal sign epistasis (RSE), indicating that adaptive landscapes for RNA viruses maybe highly rugged. Finally, we found that the magnitude of epistasis correlated negatively with the average effect of mutations. Overall, our results are in good agreement to those previously reported for other viruses and further consolidate the view that positive epistasis is the norm for small and compact genomes that lack genetic robustness.
Data from: Diel rewiring and positive selection of ancient plant proteins enabled evolution of CAM photosynthesis in Agave
Background: Crassulacean acid metabolism (CAM) enhances plant water-use efficiency through an inverse day/night pattern of stomatal closure/opening that facilitates nocturnal CO2 uptake. CAM has evolved independently in over 35 plant lineages, accounting for ~ 6% of all higher plants. Agave species are highly heat- and drought-tolerant, and have been domesticated as model CAM crops for beverage, fiber, and biofuel production in semi-arid and arid regions. However, the genomic basis of evolutionary innovation of CAM in genus Agave is largely unknown. Results: Using an approach that integrated genomics, gene co-expression networks, comparative genomics and protein structure analyses, we investigated the molecular evolution of CAM as exemplified in Agave. Comparative genomics analyses among C3, C4 and CAM species revealed that core metabolic components required for CAM have ancient genomic origins traceable to non-vascular plants while regulatory proteins required for diel re-programming of metabolism have a more recent origin shared among C3, C4 and CAM species. We showed that accelerated evolution of key functional domains in proteins responsible for primary metabolism and signaling, together with a diel re-programming of the transcription of genes involved in carbon fixation, carbohydrate processing, redox homeostasis, and circadian control is required for the evolution of CAM in Agave. Furthermore, we highlighted the potential candidates contributing to the adaptation of CAM functional modules. Conclusions: This work provides evidence of adaptive evolution of CAM related pathways. We showed that the core metabolic components required for CAM are shared by non-vascular plants, but regulatory proteins involved in re-reprogramming of carbon fixation and metabolite transportation appear more recently. We propose that the accelerated evolution of key proteins together with a diel re-programming of gene expression were required for CAM evolution from C3 ancestors in Agave.
Data from: Divergence in strategies for coping with winter embolism among co-occurring temperate tree species: the role of positive xylem pressure, wood type and tree stature
1. In temperate ecosystems, freeze-thaw events are an important environmental stress that can induce severe xylem embolism (i.e. clogging of conduits by air bubbles) in overwintering organs of trees. However, no comparative studies of different adaptive strategies among sympatric tree species for coping with winter embolism have examined the potential role of the presence or absence of embolism refilling by positive xylem pressure. 2. We evaluated the degree of winter embolism and hydraulic architecture traits in 22 deciduous angiosperm tree species typical of temperate forest sites in NE China. Co-occurring trees growing in a local botanical garden were used to minimize variation caused by differences in proximal environmental conditions and to ensure that interspecific variation reflected genetic differences between species. 3. Four functional groups with potentially different strategies for coping with winter embolism were compared: positive xylem pressure generating species (PXP) that are all diffuse-porous, except a semi-ring-porous species, large (LDP) and small (SDP) statured diffuse-porous tree species that are unable to generate positive xylem pressure, and ring-porous species (RP). 4. The PXP group exhibited nearly full recovery from winter embolism in contrast to the other three groups, which showed persistent and relatively high degrees of hydraulic dysfunction during the subsequent growing season. The absence of a functional trade-off between hydraulic efficiency and safety against freeze-thaw induced embolism in the PXP group and the presence of a trade-off in the other three groups, suggests that the ability to generate root or stem pressure for embolism refilling may partially free some temperate tree species from adaptive constraints imposed by winter embolism formation. 5. Efficient winter embolism reversal by positive pressure in PXP species did not distinguish them from their non-xylem pressure-generating LDP counterparts in terms of various measures of xylem hydraulic efficiency during the growing season. Divergence in the ability to refill winter embolism through generation of positive xylem pressure implies a series of functional trade-offs that may partially explain the co-existence of these two types of temperate tree species.
Data from: Positive size-speed relationships in gametes and vegetative cells of Chlamydomonas reinhardtii; implications for the evolution of sperm.
It is commonly held that differences in gametes of the two sexes (anisogamy) evolved from ancestors whose gametes were similar in size and behaviour (isogamy). Underlying many hypotheses explaining anisogamy are assumed relationships between cell size and speed in the ancestral isogamous population. Using the isogamous alga Chlamydomonas reinhardtii, we explored size-speed distributions in vegetative and gamete cells of ten cell lines, and clonal data from within two cell lines. We applied an independent speed selection approach to gamete populations of C. reinhardtii, monitoring correlated responses in size following selection for high speed. We demonstrate positive size-speed relationships in clones, cell lines and artificially selected speed selection lines. We found different size-speed relationships in the two cell types of C. reinhardtii even though they overlap in size, suggesting that cell composition and/or programs of gene expression are capable of altering this relationship, and that the relationship is evolvable. The positive genetic size-speed correlation means that the division of parent vegetative cells into numerous gametes trades off against not only size but also speed, a trade-off that has not received previous attention. Our results support re-evaluating the role of speed selection in the evolution of anisogamy.
Data from: Developmental stress predicts social network position
The quantity and quality of social relationships, as captured by social network analysis, can have major fitness consequences. Various studies have shown that individual differences in social behaviour can be due to variation in exposure to developmental stress. However, whether these developmental differences translate to consistent differences in social network position is not known. We experimentally increased levels of the avian stress hormone corticosterone (CORT) in nestling zebra finches in a fully balanced design. Upon reaching nutritional independence, we released chicks and their families into two free-flying rooms, where we measured daily social networks over five weeks using passive integrated transponder tags. Developmental stress had a significant effect on social behaviour: despite having similar foraging patterns, CORT chicks had weaker associations to their parents than control chicks. Instead, CORT chicks foraged with a greater number of flock mates and were less choosy with whom they foraged, resulting in more central network positions. These findings highlight the importance of taking developmental history into account to understand the drivers of social organization in gregarious species.
Data from: Kin recognition: evidence that humans can perceive both positive and negative relatedness
The evolution of spite entails actors imposing costs on 'negative' relatives: those who are less likely than chance to share the actor's alleles and therefore more likely to bear rival alleles. Yet, despite a considerable body of research confirming that organisms can recognise positive relatives, little research has shown that organisms can recognise negative relatives. Here, we extend previous work on human phenotype matching by introducing a cue to negative relatedness: negative self-resembling faces, which differ from an average face in the opposite direction to the way an individual's own face differs from the average. Participants made trustworthiness and attractiveness judgements of pairs of opposite-sex positive and negative self-resembling faces. Analyses revealed opposing effects of positive and negative self-resembling faces on trustworthiness and attractiveness judgements. This is the first clear evidence that humans are sensitive to negative relatedness cues, and suggests potential for the adaptive allocation of spiteful behaviour.
Data from: Positioning behavior according to individual color variation improves camouflage in novel habitats
Behavior can play a key role in adaptation, especially in novel environments. Here we study how ground-perching grasshoppers that colonized street pavements as novel habitats behaviorally manage their detection rates by predators. We found that grasshoppers positioned themselves aligned with the spaces between adjacent bricks more than expected by chance. By performing a virtual predation experiment, we confirmed that this positioning behavior decreases predation rate. Surprisingly, individuals with a poorer cryptic coloration made greater use of this positioning behavior, while individuals with a better cryptic coloration relied more on background color matching. Additionally, positioning behavior interacted with other anti-predation behaviors: individuals who were positioned on the space between bricks allowed potential predators to get closer before fleeing. These results indicate that these grasshoppers showed adaptive flexibility in camouflage and escape behaviors as a function of both individual and environmental variation. Such behavioral flexibility should allow organisms to cope better with novel environments, which deserves more study especially in the current context of global change.
Data from: A positive genetic correlation between hypoxia tolerance and heat tolerance supports a controversial theory of heat stress
We used quantitative genetics to test a controversial theory of heat stress, in which animals overheat when the demand for oxygen exceeds the supply. This theory, referred to as oxygen- and capacity-limited thermal tolerance, predicts a positive genetic correlation between hypoxia tolerance and heat tolerance. We demonstrate the first genetic correlation of this kind in a model organism, Drosophila melanogaster. Genotypes more likely to fly under hypoxic stress (12% O2) were also more likely to fly under heat stress (39°C). This finding prompts new questions about mechanisms and limits of adaptation to heat stress.
Data from: Baculovirus infection triggers a positive phototactic response in caterpillars (a response to Dobson et al. Biol Letters 2015).
We recently reported that baculovirus Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) triggers positive phototaxis in Spodoptera exigua larvae, leading to death at elevated positions. Dobson et al. [1] (University of Stirling, Scotland) question our interpretation of the data. Unfortunately, Dobson et al. rely on unwarranted assumptions possibly reflecting a poor understanding of baculovirus–insect pathobiology, make invalid comparisons and fail to take relevant literature into account. Here, we recapitulate the context and interpretation of our experiments and highlight the misinterpretations by Dobson et al.
False-Positive Psychology in .txt format
<p>Data for the paper http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1850704</p> <p> </p>
FIGURE 9 in A new genus and species of phytoseiid mites (Acari: Mesostigmata) from southern Tunisia, with discussion of its phylogenetic position
FIGURE 9. Africoseiulella flechtmanni gen. nov., sp. nov. Deutonymph, ventral idiosoma.
FIGURE 6 in A new genus and species of phytoseiid mites (Acari: Mesostigmata) from southern Tunisia, with discussion of its phylogenetic position
FIGURE 6. Africoseiulella flechtmanni gen. nov., sp. nov. Male, ventral idiosoma.
FIGURE 5 in A new genus and species of phytoseiid mites (Acari: Mesostigmata) from southern Tunisia, with discussion of its phylogenetic position
FIGURE 5. Africoseiulella flechtmanni gen. nov., sp. nov. Male, dorsal shield.
FIGURE 2 in A new genus and species of phytoseiid mites (Acari: Mesostigmata) from southern Tunisia, with discussion of its phylogenetic position
FIGURE 2. Africoseiulella flechtmanni gen. nov., sp. nov., ventral idiosoma of female.
FIGURE 1 in A new genus and species of phytoseiid mites (Acari: Mesostigmata) from southern Tunisia, with discussion of its phylogenetic position
FIGURE 1. Africoseiulella flechtmanni gen. nov., sp. nov., dorsal shield of female.
FIGURES 29–30 in Newman with discussion of the taxonomic position of the Australian species, O. simplex White (Coleoptera: Cerambycidae: Cerambycinae)
FIGURES 29–30. Dorsal view of Oemona hirta: 29, male; 30, female. Scale lines: 10 mm.
FIGURES 17–18 in Newman with discussion of the taxonomic position of the Australian species, O. simplex White (Coleoptera: Cerambycidae: Cerambycinae)
FIGURES 17–18. Dorsal view of Oemona separata: 17, male; 18, female. Scale lines: 10 mm.
FIGURES 39–40 in Newman with discussion of the taxonomic position of the Australian species, O. simplex White (Coleoptera: Cerambycidae: Cerambycinae)
FIGURES 39–40. Dorsal view of Oemona plicicollis: 39, male; 40, female. Scale lines: 10 mm.
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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.