Littérature scientifique sur le sujet « Distribution d'abondance des traits »
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Articles de revues sur le sujet "Distribution d'abondance des traits"
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Carbonara, Pierluigi, Teresa Silecchia, Maria Spedicato, Alessandra Acrivulis et Giuseppe Lembo. « A GEOSTATISTICAL APPROACH TO THE ASSESSMENT OF THE SPATIAL DISTRIBUTION OF PARAPENAEUS LONGIROSTRIS (LUCAS, 1846) IN THE CENTRAL-SOUTHERN TYRRHENIAN SEA ». Crustaceana 72, no 9 (1999) : 1093–108. http://dx.doi.org/10.1163/156854099504040.
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AbstractThe spatial distribution of the abundance indices of the deep-water rose shrimp Parapenaeus longirostris was investigated applying geostatistical techniques on data collected in the central southern Tyrrhenian Sea from bottom trawl surveys carried out in the autumn since 1994. Experimental variograms (auto and cross) were constructed on the variable "abundance index", expressed in kg/km2, and those variogram models best describing the spatial continuity were detected and validated by the jackknife technique. The spatial structure of the "abundance index", exhibiting a similar pattern throughout the surveys, was described by a spherical model and characterized by a spatial continuity at a small scale level in the whole area. The linear geostatistical approach was applied by different kriging techniques and the estimates extended to the spatio-temporal dimension, in this case adopting the co-regionalized models and applying the cokriging technique. This method applied to the spatial dimension (abundance index and depth). Also, linking the spatial and temporal dimension of the abundance indices, measured in two different years, contributed to represent a more accurate picture of the abundance distribution, and allowed the detection of a temporal persistence of the localization of areas with higher abundance, reducing the standard deviation of the estimation error. This information, if coupled with an analysis of the geographical allocation of the fishing effort, could be of importance in stock assessment, allowing some variant application of the composite surplus production models. La distribution spatiale des indices d'abondance de la crevette rose d'eau profonde Parapenaeus longirostris a ete etudiee en appliquant les techniques de la geostatistique aux donnees collectees dans le centre-sud de la mer Tyrrhenienne au cours des campagnes de chalutage demersal realisees pendant l'automne, depuis 1994. Les variogrammes experimentaux (auto et cross) ont ete construits sur la variable "indice d'abondance", exprimee en kg/km2, et les modeles de variogramme decrivants le mieux la continuite spatiale ont ete determines et valides par la technique du "jackknife". La structure spatiale de l'indice d'abondance a presente le meme aspect pour tous les echantillonages; elle a ete decrite au moyen d'un modele spherique et caracterisee par une continuite spatiale a petite echelle dans toute la zone. La geostatistique lineaire a ete appliquee en utilisant differentes techniques du krigeage, et les estimations ont ete etendues a la dimension spatio-temporelle en appliquant les modeles coregionalises et la technique du cokrigeage. Cette methode, appliquee soit dans la dimension spatiale (indice d'abondance et profondeur), soit dans la dimension spatio-temporelle en considerant l'indice d'abondance echantillonne en deux annees differentes, a contribue a representer une image plus precise de la distribution de l'abondance, et a permis de detecter une persistance temporelle de la localisation des aires a plus grande abondance, en reduisant l'ecart type de l'erreur d'estimation. Cette information, avec l'analyse de l'allocation geografique de l'effort de peche, pourrait etre importante dans l'evaluation des stocks, en permettant l'application, avec quelques variantes, des modeles composites de production.
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Bach, P., M. Amanieu, T. L. Hoai et G. Lasserre. « Application du modele de distribution d'abondance de Mandelbrot a l'estimation des captures dans l'etang de Thau ». ICES Journal of Marine Science 44, no 3 (1 janvier 1988) : 235–46. http://dx.doi.org/10.1093/icesjms/44.3.235.
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Szelag-Wasielewska, E. « Distribution du picoplancton autotrophe dans la zone pélagique d'un lac méromictique (Lac Czane, Pologne) ». Revue des sciences de l'eau 18 (12 avril 2005) : 1–11. http://dx.doi.org/10.7202/705572ar.
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La composition, l'abondance et la biomasse de la communauté du picoplancton autotrophe (PPA, 0,2-2 m) ont été examinées dans un lac situé en Pologne et récemment considéré comme méromictique, le lac Czarne. Les échantillons d'eau ont été prélevés tous les mètres dans la colonne d'eau, en mars et en juillet 1998. Pendant ces deux dates, le PPA se caractérisait par des changements significatifs de densité dans la colonne d'eau. Au printemps, l'abondance la plus forte a été observée à 9 m (2,1·105 cellules·mL-1) tandis qu'en été elle est observée à 5 m (3,1·105 cellules·mL-1). À toutes les profondeurs, le PPA était dominé par des Cyanobactéries. Au printemps, dominent les cellules libres de picocyanobactéries, contrairement à l'été où les cellules coloniales étaient prépondérantes. La contribution des cellules eucaryotes était faible en termes d'abondance (<20%) et bien plus élevée en termes de biomasse, avec une valeur moyenne de 33% au printemps. La biomasse moyenne du PPA était plus élevée au printemps (12 µgC·L-1) qu'en été (8 µgC·L-1) et des différences nettes sont observées entre les saisons dans sa distribution en fonction de la profondeur.
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Simard, Annie, et Anne de Vernal. « Distribution des kystes du type Alexandrium excavatum dans les sédiments récents et postglaciaires des marges est-canadiennes ». Géographie physique et Quaternaire 52, no 3 (2 octobre 2002) : 361–71. http://dx.doi.org/10.7202/004868ar.
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Résumé Des analyses palynologiques ont été réalisées dans des échantillons de sédiments de surface de l'Atlantique Nord et de ses bassins adjacents afin de retracer la distribution des kystes des taxons toxiques du type Alexandrium excavatum . La présence de kystes le long des marges sud-scandinaves et au large des côtes sud-est canadiennes indique une préférence pour les milieux néritiques où sont enregistrées des conditions tempérées fraîches (15-17 °C en août) et des salinités relativement faibles (~32 ‰) dans les eaux de surface. Dans le secteur du golfe du Saint-Laurent, l'abondance des kystes augmente de l'estuaire vers les marges atlantiques (détroit de Cabot). L'analyse de séquences postglaciaires du golfe du Saint-Laurent révèle un maximum d'abondance des kystes du type Alexandrium excavatum autour de 9 000 ans BP, soit au début du présent interglaciaire. Cet acmé est marqué par des concen-trations particulièrement élevées (jusqu'à 104 kystes.cm -3 ) à l'embouchure du golfe du Saint-Laurent (région du détroit de Cabot). La distribution actuelle et postglaciaire des kystes du type Alexandrium excavatum laisse supposer un ensemencement régional du golfe du Saint-Laurent à partir des marges nord-atlantiques adjacentes.
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Nola, M., T. Njine, V. F. Sikati et E. Djuikom. « Distribution de Pseudomonas aeruginosa et Aeromonas hydrophila dans les eaux de la nappe phréatique superficielle en zone équatoriale au Cameroun et relations avec quelques paramètres chimiques du milieu. » Revue des sciences de l'eau 14, no 1 (12 avril 2005) : 35–53. http://dx.doi.org/10.7202/705407ar.
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Une étude microbiologique et chimique a été menée pendant un an sur les eaux de sources et de puits de Yaoundé (Cameroun). Les analyses microbiologiques ont été faites suivant la technique des membranes filtrantes, et les analyses chimiques, suivant les techniques analytiques usuelles. Les abondances maximales mensuelles de Pseudomonas aeruginosa et de Aeromonas hydrophila varient respectivement de 1 à 22x103 UFC.100 ml-1 d'eau, et de 1 à 7,8x103 UFC.100 ml-1. Ces abondances bactériennes subissent d'amples fluctuations spatio-temporelles. Les eaux de sources et de puits analysées sont faiblement bicarbonatées, douces et présentent une minéralisation faible à moyenne. Le pH varie de 3 à 5 et les concentrations en CO2 dissous, de 300 à 532 mg.l-1. Un bon nombre des caractéristiques chimiques de ces eaux est relativement stable au cours du temps, en dépit des fluctuations spatiales apparentes. Le degré de corrélation entre les paramètres chimiques et la dynamique d'abondance des bactéries isolées, est hétérogène. Cela est nettement plus marqué dans les eaux de puits, en raison des conséquences de l'exploitation humaine de ces eaux, à l'origine d'apports allochtones divers.
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Badr, Anas. « Distribution of Nulliparous Fertility Traits ». Journal of Animal and Poultry Production 11, no 5 (1 mai 2020) : 193–98. http://dx.doi.org/10.21608/jappmu.2020.104946.
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Haarsma, Anne-Jifke, et Henk Siepel. « Macro-evolutionary trade-offs as the basis for the distribution of European bats ». Animal Biology 63, no 4 (2013) : 451–71. http://dx.doi.org/10.1163/15707563-00002424.
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Bats have a high species diversity and show unique ecological traits. The distribution patterns of European bat species differ between species. In this paper we seek to explain which life history traits, or interrelations between traits, can best explain observed differences in the distribution patterns of bats. Traits are interrelated and sometimes involve trade-offs, implying that a change in one trait may have positive or negative consequences for other traits. We describe the main morphological, physiological and ecological adaptations of insectivorous European bat species. We make pair-wise relations between traits, indicating the interrelations between traits, in terms of possible trade-offs. We relate the consequences of these trade-offs to the distribution maps of the species, focusing on the traits relevant for southern and northern distribution limits. We found coarse patterns that might indicate the distribution of related species are a consequence of their physiological, morphological and ecological adaptations and the interrelations between these adaptations. Hence, we think life-history strategies can be used to explain differences in species distribution. The method presented in this paper might also be useful for other mammal groups with a high species diversity, such as Rodentia and Soricidae.
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Raymond, Anne. « Paleogeographic Distribution of Early Devonian Plant Traits ». PALAIOS 2, no 2 (1987) : 113. http://dx.doi.org/10.2307/3514640.
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Yao, Qiang, et Shawn Mehlenbacher. « DISTRIBUTION OF QUANTITATIVE TRAITS IN HAZELNUT PROGENIES ». Acta Horticulturae, no 556 (juillet 2001) : 143–62. http://dx.doi.org/10.17660/actahortic.2001.556.21.
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Menglin, Li, Zhang Xinbing, Tong Yao, Huang Jihong, Zhang Shichen, Xu Shuyi, Ding Yi et al. « Mean annual temperature mainly drives spatial pattern of plant functional traits in inland arid and semi-arid areas ». Annals of Forest Research 67, no 2 (31 décembre 2024) : 51–66. https://doi.org/10.15287/afr.2024.3467.
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The distribution pattern of different plant functional traits in arid and semi-arid areas and their environmental impact mechanism are still unclear. The aim of this study is to elucidate the spatial distribution patterns of four key plant functional traits and the effects of environmental factors on their variation in inland arid and semi-arid areas and thus provide a reference for the prediction of species distribution and biodiversity conservation in this region. We focused on wild seed plants naturally distributed in Xinjiang, and by reviewing floras and data sharing platforms, we sorted and compiled the species list and distribution, plant functional traits and environmental data, including 3,953 species information, 44,302 county-level distribution records, 3,892 plant functional traits information and 29 environmental variables. Spatial and statistical analyses were utilized to detect the spatial distribution patterns of four key plant traits in 50 × 50 km grid cells. The spatial variation in different functional traits was explored and environmental drivers were identified. The results showed that there were significant latitudinal and altitudinal gradient patterns of plant functional traits, and there were significant spatial correlations between different traits. Among the three types of environmental factors (climate, soil and habitat heterogeneity), climate factors played the most pronounced role in explaining functional traits. Mean annual temperature (MAT) was the most important driver of the spatial distribution patterns of each trait. Overall, vegetative and reproductive growth of plants is more favorable in areas with higher temperatures, abundant precipitation, fertile soils and high habitat heterogeneity, which is mainly reflected in higher plant height, larger leaves, earlier flowering time and longer flowering duration.
Thèses sur le sujet "Distribution d'abondance des traits"
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Rondeau, Nathan. « Règles d'assemblage et dynamiques des communautés végétales prairiales : apports de l'étude des distributions de traits ». Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2024. http://www.theses.fr/2024UCFA0175.
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Comprendre et prédire la dynamique de la biodiversité sous contraintes du changement global représente un défi scientifique majeur. Cependant, la réponse de la biodiversité au changement global est intrinsèquement complexe. En effet, les facteurs de changement en jeu n'affectent pas seulement la diversité des espèces et leur abondance, mais modifient également les interactions biotiques entre espèces, ce qui impacte l‘assemblage des communautés et leurs dynamiques. Dans ce contexte, l'étude de la diversité des traits fonctionnels pourrait permettre des avancées significatives car les traits reflètent la manière dont les espèces répondent et influencent leur environnement. Pour rendre l'approche fonctionnelle opérationnelle à l'étude de la complexité des systèmes écologiques, nous avons développé une démarche analytique novatrice qui repose sur l'étude des formes de distribution de traits. La forme des distributions de traits peut être caractérisée par une la relation entre la skewness et la kurtosis : la SKR. Plus précisément, nous avons développé deux indicateurs clés (Chapitre 1), dérivés de la SKR : le TADeve qui caractérise l'équitabilité fonctionnelle, et le TADstab qui caractérise la stabilité des distributions de traits.En nous appuyant sur les prairies permanentes comme modèle d'étude, nous avons mis en avant la pertinence de l'étude de l'équitabilité (TADeve) et de la stabilité (TADstab) des distributions de traits afin de dissocier l'influence de processus déterministes (p.ex. filtre de l'habitat, différentiation de niche) de la stochasticité inhérente aux systèmes écologiques (Chapitre 1). La mobilisation d'un jeu de données de suivi de prairies permanentes gérées de manière contrastée sur le long terme (17 ans), nous a permis de montrer que la dynamique des distributions de traits n'était pas aléatoire mais dépendante des pratiques de gestion (Chapitre 2). Les prairies gérées de manière intensive (haut niveau de fertilisation) sont associées à des distributions de traits instables et inéquitables. Ces résultats sont cohérents avec un scénario théorique du « filtre de l'habitat » et l'effet d'une compétition intense limitant la diversité. Dans le cas des prairies gérées de manière extensive (absence de fertilisation), les distributions de traits sont remarquablement équitables et stables. Ces résultats sont cohérents avec un scénario théorique de la « différenciation de niche » prédisant une coexistence stable d'espèces fonctionnellement contrastées. Par ailleurs, nous avons montré que l'arrêt de la fertilisation entraîne, en quelques années, une convergence vers des distributions de traits équitables et stables, favorisant ainsi le recrutement à long terme d'une flore prairiale riche et diversifiée. Nous montrons également que l'équitabilité et la stabilité des distributions de traits s'expliqueraient par l'émergence d'une complémentarité entre espèces dominantes et subordonnées permettant une stabilisation sur le long terme de l'assemblage fonctionnel et de toute la communauté végétale (Chapitre 3). Enfin, une étude comparative des patrons de diversité fonctionnelle, entre des communautés prairiales gérées et des communautés végétales naturelles, nous a permis de montrer que ces communautés partagent des organisations fonctionnelles similaires. L'observation de patrons communs dans le temps et dans l'espace suggère l'existence de règles générales déterminant à la fois l'assemblage, la diversité et la dynamique des communautés prairiales.En conclusion, l'approche SKR semble adaptée à l'étude de systèmes complexes dynamiques, tels que les systèmes écologiques en contexte de changement global. A l'ère de l'anthropocène, l'identification de règles générales d'assemblage basées sur les traits permettrait de concevoir des modes de gestion adaptés à la préservation et à la restauration de la biodiversité, ainsi qu'au maintien de la multifonctionnalité des écosystèmesUnderstanding and predicting the dynamics of biodiversity under global change is a major scientific challenge. However, biodiversity responses to global change are inherently complex. Drivers of change not only affect species diversity and abundance but also alter biotic interactions between species, which may impact community assembly and dynamics. In this context, studying the diversity of functional traits within communities could lead to significant advances, as traits reflect how species respond to and influence their environment. To make the trait-based approach operational for the study of complex ecological systems, we developed an innovative analytical framework based on the study of the shapes of trait distributions. The shapes of trait distributions can be characterised by an inequality between the skewness and the kurtosis, the Skewness-Kurtosis Relationship (SKR). Using this inequality, we developed two key indicators (Chapter 1): the TADeve, which characterises the evenness of trait distributions, and the TADstab, which characterises the stability of trait distributions.Using permanent grasslands as a study model, we highlighted the relevance of studying the evenness (TADeve) and stability (TADstab) of trait distributions in order to disentangle the influence of deterministic processes (e.g. habitat filtering, niche differentiation), while accounting for the inherent stochasticity of ecological systems (Chapter 1). Using a long-term dataset of managed permanent grasslands (17-years), we demonstrated that the temporal variability of trait distributions was not random, but depended on management practices (Chapter 2). Intensively managed grasslands (high levels of fertilisation) are associated with unstable and uneven trait distributions. These results are consistent with predictions of the “habitat filtering” theory and the occurrence of intense competition between plant species that limit local diversity. Conversely, extensively managed grasslands (no fertilisation) were linked to remarkably even and stable trait distributions over time. Furthermore, we also showed that the cessation of fertilisation in extensively-managed grasslands led to a rapid convergence towards even and stable trait distributions, which promoted the long-term recruitment and persistence of a rich and diverse grassland flora. These findings are consistent with a theoretical scenario of niche differentiation, which predicts a stable coexistence among functionally contrasting species. Finally, we found that the high evenness and stability of trait distributions, in extensively managed grasslands, are explained by a functional complementarity between dominant and subordinate species, facilitating the long-term stabilisation of the functional assemblage and of the entire plant community (Chapter 3). Using observational data from various ecological context, we showed that semi-natural and natural plant communities shared a similar functional organisation. The observation of common functional patterns over space and time suggests the existence of general rules governing the assembly, diversity, and dynamics of plant communities.In conclusion, the SKR approach appears to be a suitable tool to study complex dynamic systems, such as ecological systems in the context of global change. In the Anthropocene era, identifying general assembly rules based on functional traits could enable the design of management methods adapted to the conservation and restoration of biodiversity, as well as the maintenance of ecosystem multifunctionality
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Brengdahl, Martin. « Differentiation of dispersive traits under a fluctuating range distribution in Asellus aquaticus ». Thesis, Linköpings universitet, Biologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-108119.
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Knowledge about dispersion is of utmost importance for understanding populations’ reaction to changes in the environment. Expansion of a population range brings with it both spatial sorting and over time, spatial selection. This means that dispersion rates increases over time at the expanding edge. Most studies have so far been performed on continuously expanding populations. This study aims to bring more knowledge about dispersal biology in dynamic systems. I studied dispersal traits in two permanent and two seasonal vegetation habitats of an isopod (Asellus aquaticus), for which differentiation between habitat types has previously been shown. I quantified differences in displacement (dispersal rate) and three morphological traits, head angle (body streamline) and leg of the third and seventh pair of legs. Isopods from the seasonal vegetation had higher displacement rates than animals from permanent vegetation. This inclines that mechanisms driving spatial selection in expanding population ranges also exist in dynamic systems. The more streamlined isopods found in seasonal sites further points towards spatial sorting by dispersion capability. Because no effect of permanence was found on leg length and there was no correlation between streamlining and displacement, the higher dispersion among animals from seasonal habitats most likely derives from behavioral differences.
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Rosmaninho, Teresa Charrua. « Distribution patterns and functional traits of nematode meiofauna assemblages in Sado Estuary (Portugal) ». Master's thesis, Universidade de Évora, 2020. http://hdl.handle.net/10174/27092.
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Estuaries are naturally stressed systems with a high degree of variability in their physical-chemical characteristics. The natural gradient of salinity, linked with other gradients (e.g. sediment type and dynamics, oxygen availability, temperature and current speed) are well documented as important factors in determining temporal and spatial variations in meiofauna communities. Among the estuarine biological components, meiobenthic communities are good indicators of environmental conditions and therefore changes in their density, diversity, structure and functioning indicate important alterations of the ecosystem. In fact, the phylum Nematoda are the ideal indicator group because they are the most diverse and abundant meiofaunal metazoans of aquatic habitats. The main aim of this study was to advance the general understanding of the spatial distribution patterns of the nematode assemblages along the Sado estuarine gradient. There were analysed structural components of nematode assemblages (abundance, species richness and diversity metrics) as well as functional attributes such as Maturity Index and Trophic Diversity Index. Additionally, multivariate analysis on community data was performed, together with Redundancy Analysis to understand which environmental factors explain the variations in the community. The results showed significant differences in the nematode structural assemblage patterns among the estuary sections. The abundance and diversity of nematodes were related with environmental variables including TOM (Total Organic Matter) concentration, the sediment grain size and the levels of dissolved oxygen. The sections with the highest TOM and lowest oxygen concentration were dominated by the opportunistic genera that were more resistant to unfavourable conditions and were responsible for low species richness. Functional attributes did not exhibit any significant differences among Estuary sections. As a conclusion, nematodes assemblages turned to be good bioindicators of heterogenous environmental conditions of this estuary, especially regarding the detection of sites with higher TOM concentration; Padrões de distribuição espacial das comunidades de nematodes bentónicos e das suas características funcionais no Estuário do Sado (Portugal).
Resumo:
Os estuários são sistemas naturalmente perturbados, com grande variabilidade nas suas características físicas e químicas. O gradiente natural de salinidade, associado a outros gradientes (por exemplo, granulometria, hidrodinamismo, oxigénio, temperatura e correntes das marés), estão bem documentados como sendo fatores determinantes para as variações temporais e espaciais das comunidades de meiofauna. Entre os diferentes componentes biológicos associados a um ambiente estuarino, as comunidades meiobentónicas são consideradas bons indicadores das condições ambientais. Isto porque, quando existem alterações na sua abundância, estrutura funcional pode ser resultado do efeito de alterações nos ecossistemas. Nematoda é o grupo taxonómico da meiofauna que em geral é mais abundante e é considerado um bom indicador ecológico. O principal objetivo deste estudo é analisar o padrão de distribuição espacial das comunidades de nematodes ao longo do gradiente estuarino do estuário do Sado. Foram analisadas variáveis ambientais consideradas determinantes para os padrões de distribuição da abundância e composição de géneros ao longo do estuário do Sado, assim como para a distribuição dos atributos funcionais das comunidades. Através da análise multivariável das abundância e diversidade comunidades foi possível determinar os fatores ambientais que melhor explicam as variações na comunidade. Também foi feita analise multivariada com base nos dados das comunidades tais como a Analise de Redundância para entender quais os fatores ambientais que melhor explicam as variações das comunidades. Os resultados mostram diferenças significativas na densidade e diversidade das comunidades de nematodes entre as várias secções do estuário. A densidade de nematodes apresentou relação com diferentes variáveis ambientais analisadas, tais como a concentração de TOM (matéria orgânica total), granulometrias e consequentemente os níveis de oxigénio dissolvido. Nas seções com maior TOM e menor concentração de oxigênio verificou-se que os géneros oportunistas eram mais abundantes, sendo estes mais resistentes a condições desfavoráveis e responsáveis pela baixa riqueza de espécies. As características funcionais não apresentaram diferenças significativas entre as seções do estuário. Pode concluir-se que as comunidades de nematodes se tornaram bons bioindicadores de condições ambientais heterogêneas deste estuário, principalmente quanto à deteção de sítios com maior concentração de TOM.
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Meek, Sarah. « Functional traits as drivers of bryophyte species distribution along a tropical elevation gradient ». Thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/26658.
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Palcy, Chrystèle. « Le nématode trichostrongle Trichostrongylus axei : distribution géographique, traits de vie et résistance aux benzimidazoles ». Thesis, Tours, 2008. http://www.theses.fr/2008TOUR3117.
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ROCCHIA, EMANUEL. « Temporal variation of species distribution and species morphological traits along altitude in the Alps ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2016. http://hdl.handle.net/10281/131144.
Texte intégralRésumé :
Many species have shown recent shifts in their distribution in response to environmental changes, in particular to climate change, mostly moving towards higher latitudes and/or altitudes. In this framework, it’s crucial to determine temporal variation in species occurrence or abundance along altitudinal gradients in order to detect changes in altitudinal shifts and to assess sensitivity of mountain species to land use and climate change.
The main purpose of the research was to detect temporal changes in species distribution along altitudinal gradients in the Alps at different levels of ecological organization. The Phd thesis is divided into four different chapters: 1) Detecting range altitudinal shifts of mountain birds in time: a comparison between two alpine areas, 2) To shift or not to shift? The role of climate and land-use changes in shaping the altitudinal distribution of birds in time, 3) Multi taxa distribution along altitude: 5 years data from the Western Alps, 4) Morphometric variation of ground beetles along an altitudinal gradient.
For the first study we investigated how birds species distributions changed in time between two different alpine areas. The second chapter focused on understanding which was the major driver between land cover and temperature changes in determining birds altitudinal shifts. The third part was based on a multi taxa approach in order to detect and compare temporal changes in species elevational distribution of three faunistic groups: ground beetles, butterflies and birds. The aim of the last chapter consisted in detecting changes of 11 morphometric variables of 5 ground beetles species along an altitudinal gradient starting from 1200 m to 2700 m asl.
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Koladjo, Babagnidé François. « Estimation non paramétrique du nombre d'espèces : Application à l'étude de la faune ichtyologique du bassin du fleuve Ouëmé ». Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112153.
Texte intégralRésumé :
Ce manuscrit est structuré en deux parties. La première partie composée des chapitres 2à 4 aborde le problème d'estimation du nombre de classes dans une population avec une application en écologie. La deuxième partie, correspondant au chapitre 5,concerne la mise en oeuvre de méthodes statistiques pour analyser des données de pêche. Dans la première partie, nous considérons une population hétérogène subdiviséeen plusieurs classes. À partir d'un échantillon, les effectifs d'individus observés parclasse, encore appelés abondances, sont utilisés pour estimer le nombre total declasses dans la population. Dans la littérature consacrée à l'estimation du nombrede classes, les méthodes basées sur un mélange de distributions de Poisson semblentêtre les plus performantes (voir par exemple les travaux de Chao and Bunge (2002)dans le cadre paramétrique et celui de Wang and Lindsay (2005) dans un cadrenon paramétrique). La mise en oeuvre de ces approches sur des données réellesmet en évidence que la distribution des abondances peut être approchée par unedistribution convexe. Nous proposons une approche non paramétrique pour estimerla distribution des abondances sous contrainte de convexité. Cette contrainte définitun cadre théorique d'estimation d'une densité discrète. Le problème d'estimation dunombre de classes est donc abordé en deux volets. Nous montrons d'une part l'existenceet l'unicité d'un estimateur d'une densité discrète sous la contrainte de convexité.Sous cette contrainte, nous démontrons qu'une densité discrète s'écrit comme un mélange de densités triangulaires. À partir de l'algorithme de réduction du supportproposé par Groeneboom et al. (2008), nous proposons un algorithme exact pourestimer les proportions dans le mélange. D'autre part, la procédure d'estimationd'une densité discrète convexe nous sert de cadre pour l'estimation de la distributiontronquée en zéro des observations d'abondance. L'estimation de la loi tronquée obtenue est ensuite prolongée en zéro pour estimer la probabilité qu'une classe ne soit pasobservée. Ce prolongement en zéro est fait de façon à annuler la proportion dela première composante dans le mélange de densités triangulaires. Nousaboutissons à une estimation du nombre de classes à l'aide d'un modèle binomial ensupposant que chaque classe apparaît dans un échantillon par une épreuve deBernoulli. Nous montrons la convergence en loi de l'estimateur proposé. Sur le plan pratique, une application aux données réelles en écologie est présentée. La méthode est ensuite comparée à d'autres méthodes concurrentes à l'aide de simulations. La seconde partie présente l'analyse des données de pêche collectées dans le fleuveOuémé au Bénin. Nous proposons une démarche statistique permettant de regrouperles espèces selon leur profil temporel d'abondances, d'estimer le stock d'une espèceainsi que leur capturabilité par les engins de pêche artisanaleThis manuscript is structured in two parts. The #rst part composed of Chapters 2to 4 deals with the problem of estimating the number of classes in a population withan application in ecology. The second part, corresponding to Chapter 5, concernsthe application of statistical methods to analyze fisheries data.In the first part, we consider a heterogeneous population split into several classes.From a sample, the numbers of observed individuals per class, also called abun-dances, are used to estimate the total number of classes in the population. In theliterature devoted to the number of classes estimation, methods based on a mix-ture of Poisson distributions seem to be the most effcient (see for example the workof Chao and Bunge (2002) in the parametric framework and that of Wang and Lind-say (2005) in a non-parametric framework). Applications of these approaches to realdata show that the distribution of abundances can be approximated by a convexdistribution. We propose a non-parametric approach to estimate the distribution ofabundances under the constraint of convexity. This constraint defines a theoreticalframework for estimating a discrete density. The problem of estimating the numberof classes is then tackled in two steps.We show on the one hand the existence and uniqueness of an estimator of adiscrete density under the constraint of convexity. Under this constraint, we provethat a discrete density can be written as a mixture of triangular distributions. Usingthe support reduction algorithm proposed by Groeneboom et al. (2008), we proposean exact algorithm to estimate the proportions in the mixture.On the other hand, the estimation procedure of a discrete convex density is usedto estimate the zero-truncated distribution of the observed abundance data. Thezero-truncated distribution estimate is then extended at zero to derive an estimateof the probability that a class is not observed. This extension is made so as tocancel the first component in the mixture of triangular distributions. An estimateof the total number of classes is obtained through a binomial model assuming thateach class appears in a sample by a Bernoulli trial. We show the convergence inlaw of the proposed estimator. On practical view, an application to real ecologicaldata is presented. The method is then compared to other concurrent methods usingsimulations.The second part presents the analysis of fisheries data collected on the Ouémériver in Benin. We propose a statistical approach for grouping species accordingto their temporal abundance profile, to estimate the stock of a species and theircatchability by artisanal fishing gears
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Cartier, Valentine. « Chironomus salinarius (KIEFFER) et salinité : structure spatiale, traits d'histoire de vie et dynamique temporelle ». Aix-Marseille 3, 2010. http://www.theses.fr/2010AIX30031.
Texte intégralRésumé :
Chironomus salinarius est une espèce commune vivant dans les lagunes côtières, caractérisées par une forte variabilité environnementale, surtout la salinité. C. Salinarius est connue pour ses nuisances, mais les connaissances sur ses préférences écologiques restent incomplètes. Le but de cette étude est de mettre en évidence le rôle de la salinité sur la structure spatiale, les traits de vie et la dynamique de C. Salinarius. La 1ere partie porte sur la distribution en tâches de C. Salinarius dans une lagune, l'étang de Bolmon. Cette étude met en évidence l'existence de tâches de chironomes, liées à la faible profondeur et aux fortes valeurs d'oxygène, malgré des densités larvaires faibles. Nous avons émis l'hypothèse que ces faibles densités sont liées a la salinité. La 2nde partie est une étude en laboratoire. Onze salinités de 0 et 50 ont été testées pour évaluer le taux de survie et le temps de développement. Un faible taux de survie à une salinité intermédiaire (10) suggère l'existence d'une alternance entre deux stratégies physiologiques, (osmoconforme ou osmorégulation). De plus, très peu d'adultes ont émergé pour les salinités à partir de 40. De 0 à 35, nous avons observé un fort taux de survie et un allongement du temps de développement avec la salinité. Dans la 3""° partie, la dynamique de C. Salinarius est étudiée dans l'étang de Bolmon avec une approche multi-échelle. Un patron inter-annuel ressort, avec l'augmentation des densités. La variation environnementale explique en partie les variations de la population de C. Salinarius. En conclusion, la synthèse des résultats présente l'effet non-exclusif de la salinité sur la structure de la population de C. SalinariusChironomus salinarius is a common species living in coastal lagoons, which are characterized by a strong variability of environmental factors, especially salinity. C. Salinarius is well-known because of its nuisances but the knowledge of its ecological preferences remains incomplete. The aim of this study is to highlight the role of salinity on spatial structure, life history traits and population dynamics of C. Salinarius. The first part focuses on the patchy distribution of C. Salinarius in a coastal lagoon, the Bolmon lagoon. This study highlights the existence of chironomid patches, linked to shallow area and high values of dissolved oxygen, in spite of very low density of larvae. We hypothesize that low density values were linked to the salinity. The second part is a laboratory study. Eleven salinities between 0 and 50 have been tested for both survival and time of development. A very low survival rate at intermediate salinity (10) suggests the existence of an alternation between two physiological strategies (osmoconformer or osmoregulator). Moreover too few adults emerge over 40. For others salinities, between 0 and 35, there was a high survival rate but the time of development increased with the salinity level. In the third part, the population dynamics of C. Salinarius is studied in the Bolmon lagoon with a multi-scale approach. A between years pattern is highlighted, with the increase of densities. Change of environmental factors can partly explain variations of C. Salinarius population. A synthesis of our results is presented in the conclusion, which emphasises the non-exclusive effect of salinity on C. Salinarius population structure
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Costard, François. « Distribution et caractéristiques du pergélisol sur Mars : son influence sur certains traits de la géomorphologie ». Paris 4, 1990. http://www.theses.fr/1989PA040138.
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Wilding, Nicholas. « Altitudinal patterns of species distribution : are these related to variation in reproductive life history traits ? » Bachelor's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/26692.
Texte intégralLivres sur le sujet "Distribution d'abondance des traits"
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lantbruksuniversitet, Sveriges, dir. Demography, reproductive biology, and adaptive traits in Gentianella campestris and G. amarella : Evaluating grassland management for conservation by using indicator plant species. Uppsala : Swedish University of Agricultural Sciences, 1997.
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Bhasin, M. K. The distribution of genetical, morphological, and behavioural traits among the peoples of Indian region : Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, Sri Lanka. Delhi, India : Kamla-Raj Enterprises, 1992.
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Benis, A. M. Geographic Distribution of Genetic Character Traits Based on the NPA Theory of Personality. Independently Published, 2017.
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Rosbakh, Sergey, Shyam S. Phartyal, Si-Chong Chen et Peter Poschlod, dir. Functional Seed Ecology : From Single Traits to Plant Distribution Patterns, Community Assembly and Ecosystem Processes. Frontiers Media SA, 2022. http://dx.doi.org/10.3389/978-2-88976-647-5.
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Université de Paris IV : Paris-Sorbonne, dir. Distribution et caractéristiques du Pergelisol sur Mars : Son influence su certains traits de la géomorphologie. 1989.
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Dalton, Russell J. The Social Distribution of Cleavage Positions. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198830986.003.0003.
Texte intégralRésumé :
This chapter describes the realignment of social groups along the economic and cultural cleavages. It considers the social characteristics that describe someone’s social interests, such as social class, income, religion, age, gender, and other traits. The 1979 European Election Study found a clear class alignment on the economic cleavage, which partially carried over to the cultural cleavage. By 2009, professionals and the better educated had shifted to liberal cultural positions, while the working class and lesser educated became cultural conservatives. Generational gaps also increased substantially between 1979 and 2009. The chapter also considers the relationship between cleavage positions and political values, such as Left–Right attitudes, postmaterial values, and political support. Economic conservatives and cultural liberals are more satisfied with government, reflecting the policy trends of European governments. The analyses are based on the European Election Studies in 1979, 2009, and 2014.
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Hunt, John, James Rapkin et Clarissa House. The genetics of reproductive behavior. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198797500.003.0002.
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Genes play a fundamental role in the regulation and evolution of most phenotypic traits, including behavior. This chapter focuses on the genetics of reproductive behavior in insects.More specifically, the distribution of genetic effects for reproductive behavior in insects (many genes of small effect or few genes of large effect) is examined, as well as how these genes interact with each other, with genes for other important traits, and with the abiotic and social environments. The chapter concludes by discussing the wider implications of this complex genetic architecture to the evolution of reproductive behaviors in insects and outline some key directions for future research on this topic.
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Ruxton, Graeme D., William L. Allen, Thomas N. Sherratt et Michael P. Speed. Deflecting the point of attack. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199688678.003.0012.
Texte intégralRésumé :
Deflection involves prey influencing the position of the initial contact of a predator with the prey’s body, in a way that benefits the prey. These traits might be behavioural, involve morphological structures, or pigmentation and other appearance traits, or combinations thereof. The benefit to the prey is normally considered to be an increased likelihood of escaping the attack, and so the benefit to the prey comes at a cost to the predator. The anti-predatory mechanisms covered in this book vary greatly in current understanding of their taxonomic distribution, and deflection is an extreme example of this. It has been postulated to occur in a sparse and eclectic group of organisms, and the evidence for its existence is quite variable among members of this group. We spend the bulk of this chapter exploring this evidence. We argue that the evidence currently available allows some speculation on the evolutionary ecology of this anti-predatory strategy, and we develop hypotheses that aim to broaden the scope of research into deflective traits.
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Kreuder-Sonnen, Christian. Emergency Powers of International Organizations. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198832935.001.0001.
Texte intégralRésumé :
This book explores emergency politics of international organizations (IOs). It studies cases in which, based on justifications of exceptional necessity, IOs expand their authority, increase executive discretion, and interfere with the rights of their rule-addressees. This “IO exceptionalism” is observable in the crisis responses of a diverse set of institutions including the United Nations Security Council, the European Union, and the World Health Organization. Through six in-depth case studies, the book analyzes the institutional dynamics unfolding in the wake of the assumption of emergency powers by IOs. Sometimes, the exceptional competencies become normalized in the IOs’ authority structures (the “ratchet effect”). In other cases, IO emergency powers provoke a backlash that eventually reverses or contains the expansions of authority (the “rollback effect”). To explain these variable outcomes, the book draws on sociological institutionalism to develop a proportionality theory of IO emergency powers. It contends that ratchets and rollbacks are a function of actors’ ability to justify or contest emergency powers as (dis)proportionate. The claim that the distribution of rhetorical power is decisive for the institutional outcome is tested against alternative rational institutionalist explanations that focus on institutional design and the distribution of institutional power among states. The proportionality theory holds across the cases studied in this book and clearly outcompetes the alternative accounts. Against the background of the empirical analysis, the book moreover provides a critical normative reflection on the (anti) constitutional effects of IO exceptionalism and highlights a potential connection between authoritarian traits in global governance and the system’s current legitimacy crisis.
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Toniolo, Gianni, dir. The Oxford Handbook of the Italian Economy Since Unification. Oxford University Press, 2013. http://dx.doi.org/10.1093/oxfordhb/9780199936694.001.0001.
Texte intégralRésumé :
A new economic history of Italy since the country's political unification in 1861. New data and interpretations by leading international economic historians and brilliant young Italian economists to reconsider the relatively little-known story of a latecomer to "modern economic growth", who rapidly caught up with the advanced Western countries. Fresh research includes: a new set of national accounts covering the entire period 1861-2011, standard of living indicators (including income distribution from the late nineteenth century onward), productivity levels and growth rates, human and social capital, migrations, real exchange rates and changes in comparative advantages, firm size, patents, the evolution of public debt, measures and explanations of the regional divide, the allocation of credit, and data on the changing efficiency of the administrative system. The book takes a strong comparative stance to illuminate the traits of Italy's growth pattern that are common to the Western experience of "modern economic growth" and those that are idiosyncratic to the Peninsula, as well as to see how and when this medium-sized open economy successfully rode the expansionary waves of the world economy. In this vein, the book explains the rapid catch-up growth during both the pre-1914 first globalization and the second post-war "golden age" of Western capitalism, as well as the less satisfactory performances in the first decades after unification and during the recent "second globalization".
Chapitres de livres sur le sujet "Distribution d'abondance des traits"
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Haslam, Nick. « Bell-Shaped Distribution of Personality Traits ». Dans Encyclopedia of Personality and Individual Differences, 441–43. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-319-24612-3_1047.
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Haslam, Nick. « Bell-Shaped Distribution of Personality Traits ». Dans Encyclopedia of Personality and Individual Differences, 1–2. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-28099-8_1047-1.
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Forbes, Valery E., et Michael H. Depledge. « Environmental stress and the distribution of traits within populations ». Dans ECOtoxicology : Ecological Dimensions, 71–86. Dordrecht : Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-1541-1_7.
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Boltovskoy, Demetrio. « Distribution and Colonization of Limnoperna fortunei : Special Traits of an Odd Mussel ». Dans Limnoperna Fortunei, 301–11. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-13494-9_16.
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Martín-Forés, Irene, Samuel C. Andrew, Greg R. Guerin et Gallagher Rachael V. « Linking the Functional Traits of Australian Acacia Species to Their Geographic Distribution and Invasion Status ». Dans Wattles, 74–92. GB : CABI, 2023. http://dx.doi.org/10.1079/9781800622197.0005.
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Badalucco, Antonina, Rocco Auriemma, Andrea Bonifazi, Roberta Cimmaruta, Elvira De Matthaeis, Cristina Gioia Di Camillo, Valentina Esposito et al. « Checklist of amphipods of italian seas : baseline for monitoring biodiversity ». Dans Monitoring of Mediterranean Coastal Areas : Problems and Measurement Techniques, 7–13. Florence : Firenze University Press, 2024. https://doi.org/10.36253/979-12-215-0556-6.01.
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This preliminary study presents an updated checklist of amphipod crustaceans inhabiting Italian seas and provides valuable insights into their diversity, distribution, and ecological traits. By combining existing literature with unpublished data, we were able to record 500 species in Italian waters. The analyses revealed a significant increase in the number of amphipod species documented in the Country, primarily due to intensified research efforts and the introduction of non-native species. This study highlights the importance of ongoing monitoring and research to assess marine biodiversity. Future efforts should prioritize understudied groups, such as planktonic species, and those living in deep-sea marine environments.
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Soares, Filipa C., Joana M. Hancock, Jorge M. Palmeirim, Hugulay Albuquerque Maia, Tariq Stévart et Ricardo F. de Lima. « Species Ecology in the Gulf of Guinea Oceanic Islands : Distribution, Habitat Preferences, Assemblages, and Interactions ». Dans Biodiversity of the Gulf of Guinea Oceanic Islands, 171–88. Cham : Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-06153-0_7.
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AbstractThe oceanic islands of the Gulf of Guinea (Príncipe, São Tomé, and Annobón) are an exceptional centre of endemism for flora and fauna. Remarkable progress has been made in biological research during the last few decades: from species being described and reported for the first time, to general patterns of species-habitat associations found across terrestrial, coastal, and marine taxa. Despite this increase in knowledge, key aspects of Gulf of Guinea species ecology remain poorly understood. This chapter reviews existing knowledge on the biodiversity of the islands, focusing on species distributions, population abundance estimates, traits, habitat associations and interactions. To promote these islands as ecological models, and to ensure the future of their endemic-rich biodiversity, it is essential to overcome current knowledge gaps and reduce existing taxonomic, spatial, and temporal biases in the information available. Therefore, future studies should favour systematic island-wide surveys and prioritize understudied areas and taxonomic groups. Moreover, long-term monitoring studies are urgently needed to assess biodiversity trends and to advise conservation actions. The future of ecological research and conservation of the unique biodiversity of these islands must increasingly rely on the development of local biodiversity-focused scientific expertise, through outreach, capacity building, and advanced training, paired with international collaborations and the development of local organizations.
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Liu, Lu-xiang, Yong-dun Xie, Hui-jun Guo, Lin-shu Zhao, Hong-chun Xiong, Jia-yu Gu et Shi-rong Zhao. « New mutation techniques for crop improvement in China. » Dans Mutation breeding, genetic diversity and crop adaptation to climate change, 47–52. Wallingford : CABI, 2021. http://dx.doi.org/10.1079/9781789249095.0005.
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Abstract There are at least 1 billion hungry people worldwide and the Asia and Pacific region harbours the biggest estimated regional distribution of hunger. Lifting a billion people out of poverty and feeding more than 9 billion by 2050 will require increasing cereal production by 70%. Accelerating the development of agriculture to continually increase productivity should be the final approach to end poverty. Mutation techniques have played very significant roles in ensuring food security by developing new mutant germplasm and mutant varieties in China, which have generated a tremendous socio-economic impact. New mutagenesis approaches were initiated in the late 1980s by Chinese scientists, including spaceflight and heavy-ion beam irradiation used as new effective and alternative ways for crop genetic improvement. Protocols for crop mutation induction by space radiation with high-energy heavy-ion beams have been established and applied for crop breeding. More than 1030 mutant varieties with high-yielding, fine-quality and multi-resistant traits have been developed and officially released mainly in cereals, oil and vegetable crops. They have been playing an important role in agricultural production. Hundreds of rare mutant germplasm accessions with a possible breakthrough effect on main economic traits such as grain yield and quality were also identified and applied in conventional breeding programmes. The development of new mutation techniques will be heavily based on, and associated with, not only effective use of nuclear and aerospace research platforms, but also advanced plant omics and molecular biology.
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Díaz Vélez, M. Celeste, Ana E. Ferreras et Valeria Paiaro. « Seed dispersal interactions promoting plant invasions. » Dans Plant invasions : the role of biotic interactions, 90–104. Wallingford : CABI, 2020. http://dx.doi.org/10.1079/9781789242171.0090.
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Abstract Animal dispersers are essential for many non-native plants since they facilitate seed movement and might promote seed germination and seedling establishment, thereby increasing their chances of invasion. This chapter reviews the published literature on seed dispersal of non-native plant species by native and/or non-native animals. The following questions are addressed: (i) Are interactions between non-native plants and their animal dispersers evenly studied worldwide? (ii) Which are the distinctive traits (i.e. geographical origin, life form, dispersal strategy and propagule traits) of non-native plants that are dispersed by animals? (iii) Which are the most studied groups of dispersers of non-native plants around the world? (iv) Does the literature provide evidence for the Invasional Meltdown Hypothesis (non-native plant-non-native disperser facilitation)? (v) What is the role of animal dispersers at different stages of the non-native plant regeneration process? Our dataset of 204 articles indicates that geographical distribution of the studies was highly heterogeneous among continents, with the highest number coming from North America and the lowest from Asia and Central America. Most of the non-native plants involved in dispersal studies were woody species from Asia with fleshy fruits dispersed by endozoochory. More than the half of the animal dispersal agents noted were birds, followed by mammals, ants and reptiles. The dominance of bird-dispersal interactions over other animal groups was consistent across geographical regions. Although most of the studies involved only native dispersers, interactions among non-native species were detected, providing support for the existence of invasional meltdown processes. Of the total number of reviewed articles reporting seed removal, 74% evaluated seed dispersal, but only a few studies included seed germination (35.3%), seedling establishment (5.4%) or seed predation (23.5%). Finally, we discuss some research biases and directions for future studies in the area.
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Schües, Christina. « Intercorporeality : Giving Life from One Body to Another ». Dans Philosophy and Medicine, 213–30. Cham : Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-04166-2_15.
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AbstractWhen a transplant is given to another person, the body material and its importance are at the centre of attention. Yet the meanings of the body, the body material, and the bodily relationship between the donor and recipient are unclear. This essay tackles the understanding of the body with regard to the practice of stem cell transplantation between siblings. The concept of intercorporeality embraces the “family body” and a singular body, the sense of bodily belonging and bodily ownership, and a relationship that inheres within a transplant. The intercorporeal relationship is basic and primary. Thematizing it may show a reality of body transformation that is more than just the distribution of body parts. It is a material approach to the human who has a body in the sense of a living substance that can be defined biotechnologically and made available. This essay shows that even though the transplant is body material, it is always more than that: a ground for personal traits, symbols, and a particular bond between the siblings.
Actes de conférences sur le sujet "Distribution d'abondance des traits"
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Liu, Wei. « Temperature field distribution and subgrade deformation of the different traits road in G214 ». Dans 4th International Symposium on Power Electronics and Control Engineering (ISPECE 2021), sous la direction de Fengjie Cen et Yinquan Yu. SPIE, 2021. http://dx.doi.org/10.1117/12.2620256.
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« Estimation of a joint distribution for several phenotypic traits in breeding or ancient populations ». Dans Bioinformatics of Genome Regulation and Structure/ Systems Biology. institute of cytology and genetics siberian branch of the russian academy of science, Novosibirsk State University, 2020. http://dx.doi.org/10.18699/bgrs/sb-2020-199.
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Degol, Jessica. « Do Gender Distribution and Masculine/Feminine Traits in Men and Women Influence Perceptions of STEM Fields ? » Dans AERA 2024. USA : AERA, 2024. http://dx.doi.org/10.3102/ip.24.2105438.
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Degol, Jessica. « Do Gender Distribution and Masculine/Feminine Traits in Men and Women Influence Perceptions of STEM Fields ? » Dans 2024 AERA Annual Meeting. Washington DC : AERA, 2024. http://dx.doi.org/10.3102/2105438.
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Haberle, Jan. « The Effect of Simulated Distribution of Soil Mineral Nitrogen and Root Traits on Wheat Yield and Grain Nitrogen Concentration ». Dans 2006 International Symposium on Plant Growth Modeling, Simulation, Visualization and Applications (PMA). IEEE, 2006. http://dx.doi.org/10.1109/pma.2006.50.
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Brisson Nielsen, Sigrid, Laurits Frøssing, Morten Hvidtfeldt, Kristoffer L. Norheim, Frederik Roager Madsen, Celeste Porsbjerg et Asger Sverrild. « Distribution of type-2 biomarkers and association with disease traits in patients with COPD, Data from the BREATHE Cohort ». Dans ERS Congress 2024 abstracts, PA3979. European Respiratory Society, 2024. http://dx.doi.org/10.1183/13993003.congress-2024.pa3979.
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Пегливанян, Г. К. « ANALYSIS OF THE DISTRIBUTION OF GENOTYPES OF THE LCORL SNP A503G GENE IN PUSHKINSKAYA CHICKENS AND THEIR INFLUENCE ON EXTERIOR AND LIVE WEIGHT INDICATORS ». Dans Биотехнология в растениеводстве, животноводстве и сельскохозяйственной микробиологии, 51–52. Crossref, 2021. http://dx.doi.org/10.48397/arriab.2021.21.xxi.026.
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Рост и развитие животных играют важную роль в производстве, селекции и их адаптации к окружающей среде в изменяющихся климатических условиях [1]. Поиск локусов количественных признаков (QTL) — это один из методов, который предоставляет возможность понять генетическую архитектуру признаков и выявить области генома, контролирующие количественные вариации признаков [2]. Селекция с помощью молекулярных маркеров – один из способов повышения мясной продуктивности сельскохозяйственной птицы. Отбор и подбор родительских пар по хозяйственно-полезным признакам привели к формированию различных популяций в породах кур и увеличению генетического разнообразия. The growth and development of animals play an important role in the production, selection and adaptation to the environment in changing climatic conditions [1]. The search for quantitative trait loci (QTL) is one of the methods that provides an opportunity to understand the genetic architecture of traits and to identify regions of the genome that control quantitative trait variations [2]. Selection using molecular markers is one of the ways to increase the meat productivity of poultry. The selection and selection of parental pairs for economically useful traits led to the formation of various populations in chicken breeds and an increase in genetic diversity.
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Gang Ge, Yan H. Xu, Lei Zhao, Zhi Q. Wu et Lan Wu. « Notice of Retraction : Spatial distribution traits of soil organic matter and total nitrogen in the wetland of Poyang Lake, China ». Dans 2010 2nd Conference on Environmental Science and Information Application Technology (ESIAT 2010). IEEE, 2010. http://dx.doi.org/10.1109/esiat.2010.5568365.
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V.A., Minkin. « Including Information-Physical Quantit ies of Personality Traits into the International System of Units (SI) ». Dans Современная психофизиология. Технология виброизображения. Modern Psychophysiology. The Vibraimage Technology., 235–62. Crossref, 2024. http://dx.doi.org/10.25696/elsys_mpvt_07_en01.
Texte intégralRésumé :
Metrology approach to the personality traits is proposed, similar to the measurement of physical quantities of the International System of Units (SI). The analysis was made of open database of 500 subjects test including psychophysiological responses (PPR) to 48 multifactorial stimuli tied to multiple intelligences and personality vices consistently presented by Blitz Judgment program. Various equations for calculating of the current psychophysiological state (PPS) and PPR according to microvibration data of a human head, measured by vibraimage technology, are considered. Mathematical criteria are proposed for assessing the correctness of PPS and PPR calculating based on the closeness of PPR distribution to the normal distribution and the maximum correlation between PPR for stimuli, that are tied to multiple intelligences and personality vices. Based on the results of PPR analysis, it is proposed to include into the International System of Units (SI) new quantities and units — the bit (information) and the vibra (PPR) used to measure personality traits. Definitions are given for new units of personality traits measurement, based on the combination of the principles of psychology, cybernetics and physics within the framework of single metrological approach to a person as biological, cybernetics and physical object.
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В.А., Минкин. « Including Information-Physical Quantities of Personality Traits into the International System of Units (SI) ». Dans Современная психофизиология. Технология виброизображения. Modern Psychophysiology. The Vibraimage Technology., 9–39. Crossref, 2024. http://dx.doi.org/10.25696/elsys_mpvt_07_ru01.
Texte intégralRésumé :
Предложен подход к измерению характеристик личности, аналогичный измерению физических величин метрической системы измерения, лежащей в основе Международной системы единиц СИ. Проведен анализ открытой базы данных психофизиологической реакции (ПФР) 500 испытуемых на 48 многофакторных стимулов, имеющих привязку к способностям и порокам личности и последовательно предъявляемых программой Профайлер+. Рассмотрены различные формулы расчета текущего психофизиологического состояния (ПФС) и ПФР по данным микровибраций головы человека, измеряемым технологией виброизображения. Предложены математические критерии оценки корректности вычисления ПФС и ПФР на основании близости плотности ПФР к нормальному распределению и максимальной корреляции между ПФР на стимулы, имеющие привязку к способностям и порокам личности. По результатам анализа ПФР предложено введение в систему СИ новых информационно-физических величин и единиц измерений — бит и вибра, используемых для измерения характеристик личности. Даны определения новым единицам измерения характеристик личности, основанные на совмещении принципов психологии, кибернетики и физики в рамках единого метрологического подхода к человеку как биологическому, кибернетическому и физическому объекту. Metrology approach to the personality characteristics is proposed, similar to the measurement of physical quantities of the International system of units (SI). The analysis was made of the open psychophysiological responses (PPR) database of 500 subjects to 48 multifactor stimuli tied to multiple intelligences and personality vices consistently presented by Blitz Judgment program. Various equations for calculating of the current psychophysiological state (PPS) and PPR according to microvibration data of a human head, measured by vibraimage technology, are considered. Mathematical criteria are proposed for assessing the correctness of PPS and PPR calculating based on the closeness of PPR distribution to the normal distribution and the maximum correlation between PPR for stimuli that are sense tied to multiple intelligences and personality vices. Based on the results of PPR analysis, it is proposed to include into the SI new values and units — the bit and the vibra used to measure personality traits. Definitions are given for new units of personality traits measurement, based on principles combination of psychology, cybernetics and physics within the framework of the single metrological approach to a person as biological, cybernetics and physical object.
Rapports d'organisations sur le sujet "Distribution d'abondance des traits"
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Dubcovsky, Jorge, et T. (Tzion) Fahima. Validation of candidate genes for a QTL responsible for water stress tolerance and their diversity in wheat. Israel : United States-Israel Binational Agricultural Research and Development Fund, 2022. http://dx.doi.org/10.32747/2022.8134149.bard.
Texte intégralRésumé :
The main goals of this project as stated in the original proposal were to identify which of the candidate gene(s) identified in a 1.5 Mb region of wheat and rye chromosomes 1RS and 1BS were responsible for the differences in root architecture, reveal their natural variation and characterize the epistatic interactions that modulate their effect in different backgrounds. Background: Wheat is an essential crop for global food security and is well adapted to a wide variety of soils. However, the gene networks regulating different wheat root architectures remain poorly understood. Root depth and biomass distribution in the soil profile are critical traits for adaptation to water stress, and a good source for these traits is the introgression of the short arm of rye chromosome one (1RS) into common wheat. A recombinant 1RS chromosome with a small wheat 1BS introgressions and a duplicated 1RS segment (1RW) showed reduced drought tolerance and was used for the identification of the causal genes.
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Fahima, Tzion, et Jorge Dubcovsky. Map-based cloning of the novel stripe rust resistance gene YrG303 and its use to engineer 1B chromosome with multiple beneficial traits. United States Department of Agriculture, janvier 2013. http://dx.doi.org/10.32747/2013.7598147.bard.
Texte intégralRésumé :
Research problem: Bread wheat (Triticumaestivum) provides approximately 20% of the calories and proteins consumed by humankind. As the world population continues to increase, it is necessary to improve wheat yields, increase grain quality, and minimize the losses produced by biotic and abiotic stresses. Stripe rust, caused by Pucciniastriiformisf. sp. tritici(Pst), is one of the most destructive diseases of wheat. The new pathogen races are more virulent and aggressive than previous ones and have produced large economic losses. A rich source for stripe-rust resistance genes (Yr) was found in wild emmer wheat populations from Israel. Original Project goals: Our long term goal is to identify, map, clone, characterize and deploy in breeding, novel wild emmer Yr genes, and combine them with multiple beneficial traits. The current study was aiming to map and clone YrG303 and Yr15, located on chromosome 1BS and combine them with drought resistance and grain quality genes. Positional cloning of YrG303/Yr15: Fine mapping of these genes revealed that YrG303 is actually allelic to Yr15. Fine genetic mapping using large segregating populations resulted in reduction of the genetic interval spanning Yr15 to less than 0.1 cM. Physical mapping of the YrG303/Yr15 locus was based on the complete chromosome 1BS physical map of wheat constructed by our group. Screening of 1BS BAC library with Yr15 markers revealed a long BAC scaffold covering the target region. The screening of T. dicoccoidesaccession-specific BAC library with Yr15 markers resulted in direct landing on the target site. Sequencing of T. dicoccoidesBAC clones that cover the YrG303/Yr15 locus revealed a single candidate gene (CG) with conserved domains that may indicate a role in disease resistance response. Validation of the CG was carried out using EMS mutagenesis (loss-of- function approach). Sequencing of the CG in susceptible yr15/yrG303 plants revealed three independent mutants that harbour non-functional yr15/yrG303 alleles within the CG conserved domains, and therefore validated its function as a Pstresistance gene. Evaluation of marker-assisted-selection (MAS) for Yr15. Introgressions of Yr15 into cultivated wheat are widely used now. Recently, we have shown that DNA markers linked to Yr15 can be used as efficient tools for introgression of Yr15 into cultivated wheat via MAS. The developed markers were consistent and polymorphic in all 34 tested introgressions and are the most recommended markers for the introgression of Yr15. These markers will facilitate simultaneous selection for multiple Yr genes and help to avoid escapees during the selection process. Engineering of improved chromosome 1BS that harbors multiple beneficial traits. We have implemented the knowledge and genetic resources accumulated in this project for the engineering of 1B "super-chromosome" that harbors multiple beneficial traits. We completed the generation of a chromosome including the rye 1RS distal segment associated with improved drought tolerance with the Yr gene, Yr15, and the strong gluten allele 7Bx-over-expressor (7Bxᴼᴱ). We have completed the introgression of this improved chromosome into our recently released variety Patwin-515HP and our rain fed variety Kern, as well as to our top breeding lines UC1767 and UC1745. Elucidating the mechanism of resistance exhibited by Yr36 (WKS1). The WHEAT KINASE START1 (WKS1) resistance gene (Yr36) confers partial resistance to Pst. We have shown that wheat plants transformed with WKS1 transcript are resistant to Pst. WKS1 is targeted to the chloroplast where it phosphorylates the thylakoid-associatedascorbateperoxidase (tAPX) and reduces its ability to detoxify peroxides. Based on these results, we propose that the phosphorylation of tAPX by WKS1 reduces the ability of the cells to detoxify ROS and contributes to cell death. Distribution and diversity of WKS in wild emmer populations. We have shown that WKS1 is present only in the southern distribution range of wild emmer in the Fertile Crescent. Sequence analysis revealed a high level of WKS1 conservation among wild emmer populations, in contrast to the high level of diversity observed in NB-LRR genes. This phenomenon shed some light on the evolution of genes that confer partial resistance to Pst. Three new WKS1 haplotypes displayed a resistance response, suggesting that they can be useful to improve wheat resistance to Pst. In summary, we have improved our understanding of cereals’ resistance mechanisms to rusts and we have used that knowledge to develop improved wheat varieties.
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Waisel, Yoav, Bobbie McMichael et Amram Eshel. Decision Making within Plant Root Systems. United States Department of Agriculture, mars 1996. http://dx.doi.org/10.32747/1996.7613030.bard.
Texte intégralRésumé :
Architecture of a root system is the expression of the potential of various root types to branch, to grow and to coordinate with other plant organs, under the specific limitations of the environmental conditions. The present investigation has proven the following points. 1) Genotypes with different types of root systems were identified. The growth patterns of their roots and the distribution of laterals along their main axes were recorded. 2) The patterns of development of the root systems of four cotton genotypes, throughout the entire life cycle of the plants, were described, even at such a late stage of development when the total length of the roots exceeded two kilometers. To the best of our knowledge, this is the first time that an analysis of this type is accomplished. 3) The development of root systems under restrictive soil conditions were compared with those that have developed under the non-restrictive conditions of aeroponics. Results indicate that in the absence of the mechanical impedance of the soil, cotton plants develop single roots that reach the length of 6 m, and have a total root length of 2000 m. Thus, root growth is strongly inhibited by the soil, with some root types being inhibited more than others. 4) One of the important decisions, in constructing an operational root system architecture of mature plants, is the shift of the balance between various root fractions in favor of the very fine roots. 5) Root system architecture is determined, in part, by the sites of initiation of the lateral roots. This is determined genetically by the number of xylem archs and by the totuosity of the stele. Selection for such traits should be sought.
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Sela, Hanan, Eduard Akhunov et Brian J. Steffenson. Population genomics, linkage disequilibrium and association mapping of stripe rust resistance genes in wild emmer wheat, Triticum turgidum ssp. dicoccoides. United States Department of Agriculture, janvier 2014. http://dx.doi.org/10.32747/2014.7598170.bard.
Texte intégralRésumé :
The primary goals of this project were: (1) development of a genetically characterized association panel of wild emmer for high resolution analysis of the genetic basis of complex traits; (2) characterization and mapping of genes and QTL for seedling and adult plant resistance to stripe rust in wild emmer populations; (3) characterization of LD patterns along wild emmer chromosomes; (4) elucidation of the multi-locus genetic structure of wild emmer populations and its correlation with geo-climatic variables at the collection sites. Introduction In recent years, Stripe (yellow) rust (Yr) caused by Pucciniastriiformis f. sp. tritici(PST) has become a major threat to wheat crops in many parts of the world. New races have overcome most of the known resistances. It is essential, therefore, that the search for new genes will continue, followed by their mapping by molecular markers and introgression into the elite varieties by marker-assisted selection (MAS). The reservoir of genes for disease and pest resistance in wild emmer wheat (Triticumdicoccoides) is an important resource that must be made available to wheat breeders. The majority of resistance genes that were introgressed so far in cultivated wheat are resistance (R) genes. These genes, though confering near-immunity from the seedling stage, are often overcome by the pathogen in a short period after being deployed over vast production areas. On the other hand, adult-plant resistance (APR) is usually more durable since it is, in many cases, polygenic and confers partial resistance that may put less selective pressure on the pathogen. In this project, we have screened a collection of 480 wild emmer accessions originating from Israel for APR and seedling resistance to PST. Seedling resistance was tested against one Israeli and 3 North American PST isolates. APR was tested on accessions that did not have seedling resistance. The APR screen was conducted in two fields in Israel and in one field in the USA over 3 years for a total of 11 replicates. We have found about 20 accessions that have moderate stripe rust APR with infection type (IT<5), and about 20 additional accessions that have novel seedling resistance (IT<3). We have genotyped the collection using genotyping by sequencing (GBS) and the 90K SNP chip array. GBS yielded a total 341K SNP that were filtered to 150K informative SNP. The 90K assay resulted in 11K informative SNP. We have conducted a genome-wide association scan (GWAS) and found one significant locus on 6BL ( -log p >5). Two novel loci were found for seedling resistance. Further investigation of the 6BL locus and the effect of Yr36 showed that the 6BL locus and the Yr36 have additive effect and that the presence of favorable alleles of both loci results in reduction of 2 grades in the IT score. To identify alleles conferring adaption to extreme climatic conditions, we have associated the patterns of genomic variation in wild emmer with historic climate data from the accessions’ collection sites. The analysis of population stratification revealed four genetically distinct groups of wild emmer accessions coinciding with their geographic distribution. Partitioning of genomic variance showed that geographic location and climate together explain 43% of SNPs among emmer accessions with 19% of SNPs affected by climatic factors. The top three bioclimatic factors driving SNP distribution were temperature seasonality, precipitation seasonality, and isothermality. Association mapping approaches revealed 57 SNPs associated with these bio-climatic variables. Out of 21 unique genomic regions controlling heading date variation, 10 (~50%) overlapped with SNPs showing significant association with at least one of the three bioclimatic variables. This result suggests that a substantial part of the genomic variation associated with local adaptation in wild emmer is driven by selection acting on loci regulating flowering. Conclusions: Wild emmer can serve as a good source for novel APR and seedling R genes for stripe rust resistance. APR for stripe rust is a complex trait conferred by several loci that may have an additive effect. GWAS is feasible in the wild emmer population, however, its detection power is limited. A panel of wild emmer tagged with more than 150K SNP is available for further GWAS of important traits. The insights gained by the bioclimatic-gentic associations should be taken into consideration when planning conservation strategies.
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Pawlowski, Wojtek P., et Avraham A. Levy. What shapes the crossover landscape in maize and wheat and how can we modify it. United States Department of Agriculture, janvier 2015. http://dx.doi.org/10.32747/2015.7600025.bard.
Texte intégralRésumé :
Meiotic recombination is a process in which homologous chromosomes engage in the exchange of DNA segments, creating gametes with new genetic makeup and progeny with new traits. The genetic diversity generated in this way is the main engine of crop improvement in sexually reproducing plants. Understanding regulation of this process, particularly the regulation of the rate and location of recombination events, and devising ways of modifying them, was the major motivation of this project. The project was carried out in maize and wheat, two leading crops, in which any advance in the breeder’s toolbox can have a huge impact on food production. Preliminary work done in the USA and Israeli labs had established a strong basis to address these questions. The USA lab pioneered the ability to map sites where recombination is initiated via the induction of double-strand breaks in chromosomal DNA. It has a long experience in cytological analysis of meiosis. The Israeli lab has expertise in high resolution mapping of crossover sites and has done pioneering work on the importance of epigenetic modifications for crossover distribution. It has identified genes that limit the rates of recombination. Our working hypothesis was that an integrative analysis of double-strand breaks, crossovers, and epigenetic data will increase our understanding of how meiotic recombination is regulated and will enhance our ability to manipulate it. The specific objectives of the project were: To analyze the connection between double-strand breaks, crossover, and epigenetic marks in maize and wheat. Protocols developed for double-strand breaks mapping in maize were applied to wheat. A detailed analysis of existing and new data in maize was conducted to map crossovers at high resolution and search for DNA sequence motifs underlying crossover hotspots. Epigenetic modifications along maize chromosomes were analyzed as well. Finally, a computational analysis tested various hypotheses on the importance of chromatin structure and specific epigenetic modifications in determining the locations of double-strand breaks and crossovers along chromosomes. Transient knockdowns of meiotic genes that suppress homologous recombination were carried out in wheat using Virus-Induced Gene Silencing. The target genes were orthologs of FANCM, DDM1, MET1, RECQ4, and XRCC2.
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Cytryn, Eddie, Mark R. Liles et Omer Frenkel. Mining multidrug-resistant desert soil bacteria for biocontrol activity and biologically-active compounds. United States Department of Agriculture, janvier 2014. http://dx.doi.org/10.32747/2014.7598174.bard.
Texte intégralRésumé :
Control of agro-associated pathogens is becoming increasingly difficult due to increased resistance and mounting restrictions on chemical pesticides and antibiotics. Likewise, in veterinary and human environments, there is increasing resistance of pathogens to currently available antibiotics requiring discovery of novel antibiotic compounds. These drawbacks necessitate discovery and application of microorganisms that can be used as biocontrol agents (BCAs) and the isolation of novel biologically-active compounds. This highly-synergistic one year project implemented an innovative pipeline aimed at detecting BCAs and associated biologically-active compounds, which included: (A) isolation of multidrug-resistant desert soil bacteria and root-associated bacteria from medicinal plants; (B) invitro screening of bacterial isolates against known plant, animal and human pathogens; (C) nextgeneration sequencing of isolates that displayed antagonistic activity against at least one of the model pathogens and (D) in-planta screening of promising BCAs in a model bean-Sclerotiumrolfsii system. The BCA genome data were examined for presence of: i) secondary metabolite encoding genes potentially linked to the anti-pathogenic activity of the isolates; and ii) rhizosphere competence-associated genes, associated with the capacity of microorganisms to successfully inhabit plant roots, and a prerequisite for the success of a soil amended BCA. Altogether, 56 phylogenetically-diverse isolates with bioactivity against bacterial, oomycete and fungal plant pathogens were identified. These strains were sent to Auburn University where bioassays against a panel of animal and human pathogens (including multi-drug resistant pathogenic strains such as A. baumannii 3806) were conducted. Nineteen isolates that showed substantial antagonistic activity against at least one of the screened pathogens were sequenced, assembled and subjected to bioinformatics analyses aimed at identifying secondary metabolite-encoding and rhizosphere competence-associated genes. The genome size of the bacteria ranged from 3.77 to 9.85 Mbp. All of the genomes were characterized by a plethora of secondary metabolite encoding genes including non-ribosomal peptide synthase, polyketidesynthases, lantipeptides, bacteriocins, terpenes and siderophores. While some of these genes were highly similar to documented genes, many were unique and therefore may encode for novel antagonistic compounds. Comparative genomic analysis of root-associated isolates with similar strains not isolated from root environments revealed genes encoding for several rhizospherecompetence- associated traits including urea utilization, chitin degradation, plant cell polymerdegradation, biofilm formation, mechanisms for iron, phosphorus and sulfur acquisition and antibiotic resistance. Our labs are currently writing a continuation of this feasibility study that proposes a unique pipeline for the detection of BCAs and biopesticides that can be used against phytopathogens. It will combine i) metabolomic screening of strains from our collection that contain unique secondary metabolite-encoding genes, in order to isolate novel antimicrobial compounds; ii) model plant-based experiments to assess the antagonistic capacities of selected BCAs toward selected phytopathogens; and iii) an innovative next-generation-sequencing based method to monitor the relative abundance and distribution of selected BCAs in field experiments in order to assess their persistence in natural agro-environments. We believe that this integrated approach will enable development of novel strains and compounds that can be used in large-scale operations.
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Blum, Abraham, Henry T. Nguyen et N. Y. Klueva. The Genetics of Heat Shock Proteins in Wheat in Relation to Heat Tolerance and Yield. United States Department of Agriculture, août 1993. http://dx.doi.org/10.32747/1993.7568105.bard.
Texte intégralRésumé :
Fifty six diverse spring wheat cultivars were evaluated for genetic variation and heritability for thermotolerance in terms of cell-membrane stability (CMS) and triphenyl tetrazolium chloride (TTC) reduction. The most divergent cultivars for thermotolerance (Danbata-tolerant and Nacozari-susceptible) were crossed to develop an F8 random onbred line (RIL) population. This population was evaluated for co-segragation in CMS, yield under heat stress and HSP accumulation. Further studies of thermotolerance in relations to HSP and the expression of heterosis for growth under heat stress were performed with F1 hybrids of wheat and their parental cultivars. CMS in 95 RILs ranged from 76.5% to 22.4% with 71.5% and 31.3% in Danbata and Nacozari, respectively. The population segregated with a normal distribution across the full range of the parental values. Yield and biomass under non-stress conditions during the normal winter season at Bet Dagan dit not differ between the two parental cultivar, but the range of segregation for these traits in 138 RILs was very high and distinctly transgressive with a CV of 35.3% and 42.4% among lines for biomass and yield, respectively. Mean biomass and yield of the population was reduced about twofold when grown under the hot summer conditions (irrigated) at Bet Dagan. Segregation for biomass and yield was decreased relative to the normal winter conditions with CV of 20.2% and 23.3% among lines for biomass and yield, respectively. However, contrary to non-stress conditions, the parental cultivars differed about twofold in biomass and yield under heat stress and the population segregated with normal distribution across the full range of this difference. CMS was highly and positively correlated across 79 RILs with biomass (r=0.62**) and yield (r=0.58**) under heat stress. No such correlation was obtained under the normal winter conditions. All RILs expressed a set of HSPs under heat shock (37oC for 2 h). No variation was detected among RILs in high molecular weight HSP isoforms and they were similar to the patterns of the parental cultivars. There was a surprisingly low variability in low molecular weight HSP isoforms. Only one low molecular weight and Nacozari-specific HSP isoform (belonging to HSP 16.9 family) appeared to segregate among all RILs, but it was not quantitatively correlated with any parameter of plant production under heat stress or with CMS in this population. It is concluded that this Danbata/Nacozari F8 RIL population co-segregated well for thermotolerance and yield under heat stress and that CMS could predict the relative productivity of lines under chronic heat stress. Regretfully this population did not express meaningful variability for HSP accumulation under heat shock and therefore no role could be seen for HSP in the heat tolerance of this population. In the study of seven F1 hybrids and their parent cultivars it was found that heterosis (superiority of the F1 over the best parent) for CMs was generally lower than that for growth under heat stress. Hybrids varied in the rate of heterosis for growth at normal (15o/25o) and at high (25o/35o) temperatures. In certain hybrids heterosis for growth significantly increased at high temperature as compared with normal temperature, suggesting temperature-dependent heterosis. Generally, under normal temperature, only limited qualitative variation was detected in the patterns of protein synthesis in four wheat hybrids and their parents. However, a singular protein (C47/5.88) was specifically expressed only in the most heterotic hybrid at normal temperature but not in its parent cultivars. Parental cultivars were significantly different in the sets of synthesized HSP at 37o. No qualitative changes in the patterns of protein expression under heat stress were correlated with heterosis. However, a quantitative increase in certain low molecular weight HSP (mainly H14/5.5 and H14.5.6, belonging to the HSP16.9 family) was positively associated with greater heterosis for growth at high temperature. None of these proteins were correlated with CMS across hybrids. These results support the concept of temperature-dependent heterosis for growth and a possible role for HSP 16.9 family in this respect. Finally, when all experiments are viewed together, it is encouraging to find that genetic variation in wheat yield under chronic heat stress is associated with and well predicted by CMS as an assay of thermotolerance. On the other hand the results for HSP are elusive. While very low genetic variation was expressed for HSP in the RIL population, a unique low molecular weight HSP (of the HSP 16.9 family) could be associated with temperature dependant heterosis for growth.
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Guy, Charles, Gozal Ben-Hayyim, Gloria Moore, Doron Holland et Yuval Eshdat. Common Mechanisms of Response to the Stresses of High Salinity and Low Temperature and Genetic Mapping of Stress Tolerance Loci in Citrus. United States Department of Agriculture, mai 1995. http://dx.doi.org/10.32747/1995.7613013.bard.
Texte intégralRésumé :
The objectives that were outlined in our original proposal have largely been achieved or will be so by the end of the project in February 1995 with one exception; that of mapping cold tolerance loci based on the segregation of tolerance in the BC1 progeny population. Briefly, our goals were to 1) construct a densely populated linkage map of the citrus genome: 2) map loci important in cold and/or salt stress tolerance; and 3) characterize the expression of genes responsive to cold land salt stress. As can be seen by the preceding listing of accomplishments, our original objectives A and B have been realized, objective C has been partially tested, objective D has been completed, and work on objectives E and F will be completed by the end of 1995. Although we have yet to map any loci that contribute to an ability of citrus to maintain growth when irrigated with saline water, our very encouraging results from the 1993 experiment provides us with considerable hope that 1994's much more comprehensive and better controlled experiment will yield the desired results once the data has been fully analyzed. Part of our optimism derives from the findings that loci for growth are closely linked with loci associated with foliar Cl- and Na+ accumulation patterns under non-salinization conditions. In the 1994 experiment, if ion exclusion or sequestration traits are segregating in the population, the experimental design will permit their resolution. Our fortunes with respect to cold tolerance is another situation. In three attempts to quantitatively characterize cold tolerance as an LT50, the results have been too variable and the incremental differences between sensitive and tolerant too small to use for mapping. To adequately determine the LT50 requires many plants, many more than we have been able to generate in the time and space available by making cuttings from small greenhouse-grown stock plants. As it has turned out, with citrus, to prepare enough plants needed to be successful in this objective would have required extensive facilities for both growing and testing hardiness which simply were not available at University of Florida. The large populations necessary to overcome the variability we encountered was unanticipated and unforeseeable at the project's outset. In spite of the setbacks, this project, when it is finally complete will be exceedingly successful. Listing of Accomplishments During the funded interval we have accomplished the following objectives: Developed a reasonably high density linkage map for citrus - mapped the loci for two cold responsive genes that were cloned from Poncirus - mapped the loci for csa, the salt responsive gene for glutathione peroxidase, and ccr a circadian rhythm gene from citrus - identified loci that confer parental derived specific DNA methylation patterns in the Citrus X Poncirus cross - mapped 5 loci that determine shoot vigor - mapped 2 loci that influence leaf Na+ accumulation patterns under non-saline conditions in the BC1 population - mapped 3 loci that influence leaf Na+ accumulation paterns during salt sress - mapped 2 loci that control leaf Cl- accumulation patterns under non-saline conditions - mapped a locus that controls leaf Cl- accumulation patterns during salt stress Screened the BC1 population for growth reduction during salinization (controls and salinized), and cold tolerance - determined population variation for shoot/root ratio of Na+ and Cl- - determined levels for 12 inorganic nutrient elements in an effort to examine the influence of salinization on ion content with emphasis on foliar responses - collected data on ion distribution to reveal patterns of exclusion/sequestration/ accumulation - analyzed relationships between ion content and growth Characterization of gene expression in response to salt or cold stress - cloned the gene for the salt responsive protein csa, identified it as glutathione peroxidase, determined the potential target substrate from enzymatic studies - cloned two other genes responsive to salt stress, one for the citrus homologue of a Lea5, and the other for an "oleosin" like gene - cold regulated (cor) genes belonging to five hybridization classes were isolated from Poncirus, two belonged to the group 2 Lea superfamily of stress proteins, the others show no significant homology to other known sequences - the expression of csa during cold acclimation was examined, and the expression of some of the cor genes were examined in response to salt stress - the influence of salinization on cold tolerance has been examined with seedling populations - conducted protein blot studies for expression of cold stress proteins during salt stress and vice versa