79 resultados para ecology of individuals


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The dominance of ''ecosystem services'' as a guiding concept for environmental management - where it appears as a neutral, obvious, taken-for-granted concept - hides the fact that there are choices implicit in its framing and in its application. In other words, it is a highly political concept, and its utility depends on the arena in which it is used and what it is used for. Following a political ecology framework, and based on a literature review, bibliometric analyses, and brief examples from two tropical rainforest countries, this review investigates four moments in the construction and application of the ecosystem services idea: socio-historical (the emergence of the discourse), ontological (what knowledge does the concept allow?), scientific (difficulties in its practical application), and political (who wins, who loses?). We show how the concept is a boundary object with widespread appeal, trace the discursive and institutional context within which it gained traction, and argue that choices of scale, definition, and method in measuring ecosystem services frustrate its straightforward application. As a result, it is used in diverse ways by dif- ferent interests to justify different kinds of interventions that at times might be totally opposed. In Madagascar, the ecosystem services idea is mainly used to justify forest conservation in ways open to cri- tique for its neoliberalization of nature or disempowerment of communities. In contrast, in the Brazilian Amazon, the discourse of ecosystem services has served the agendas of traditional populations and family farm lobbies. Ecosystem services, as an idea and tool, are mobilized by diverse actors in real-life situa- tions that lead to complex, regionally particular and fundamentally political outcomes.

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Objectifs En EHPAD, selon les recommandations de la Haute Autorité de santé (HAS), la prise en charge non médicamenteuse des troubles psychocomportementaux associés à la maladie d'Alzheimer ou aux syndromes apparentés, implique une réorganisation, une formation spécifique du personnel et du temps. Se pose ici la question du rôle des bénévoles dans cette prise en charge. Matériels et méthodes Enquête descriptive à partir de questionnaires distribués aux différents intervenants (bénévoles, professionnels de santé et aidants familiaux) d'une unité protégée de l'EHPAD de la clinique du Diaconat (Colmar, France) et spécifiquement élaborés pour évaluer leur vécu de l'expérience de bénévolat dans la prise en charge des résidents souffrant d'une maladie d'Alzheimer ou d'un syndrome apparenté. Résultats Sur les 101 questionnaires qui ont été remplis, 85,7 % des aidants, 60 % des bénévoles et 42,1 % des professionnels constataient des bénéfices pour eux-mêmes. Les professionnels et les aidants avaient confiance dans l'intervention des bénévoles. Cependant, les bénévoles semblaient manquer de compétence pour le soutien des aidants et dans les techniques de communication avec les résidents. Les points essentiels pour permettre un fonctionnement harmonieux entre les différents intervenants étaient de bien définir préalablement le rôle de bénévoles et d'en informer les autres intervenants, de former les bénévoles à ce rôle et de favoriser la communication entre les bénévoles et les professionnels. Conclusion Cette enquête montre que les bénévoles ont une place aux côtés des équipes soignantes pour participer à la prise en charge non médicamenteuse des personnes atteintes de maladie d'Alzheimer ou syndromes apparentés. Ils ont une position singulière et jouent un rôle complémentaire de celui des soignants et des aidants. Objectives According to the recommendation of the French High Authority of Health (HAS), the non-pharmaceutical management of psycho-behavioural disorders associated with Alzheimer's disease or related disorders in a nursing home, involves reorganization an specific training for staff members and time. This raises the question of the role of volunteering in this approach. Materials and methods A descriptive survey using questionnaires distributed to various stakeholders (volunteers, healthcare professionals and caregivers) of a protected unit of the nursing home of the Diaconat clinic (Colmar, France) and specifically designed to assess their experience of the volunteering in supporting residents suffering from Alzheimer's diseases or related disorders. Results Of the 101 questionnaires that were filled in, 85.7% of caregivers, 60% of volunteers and 42.1% of professionals recorded benefits for themselves. Professionals and informal carers had confidence in the intervention of volunteers. However, volunteers seemed to lack skills to support informal caregivers and specific knowledge about the technique of communicating with residents. The key points to favor harmonious collaborations between the different stakeholders were: to properly define the role of volunteers and to inform other stakeholders about this role previously, and to specifically educate themselves in this task and to promote communication between volunteers and all other professionals. Conclusion This study shows that volunteers have a place alongside medical teams to participate in the non-pharmaceutical treatment for people with Alzheimer's disease or related syndromes. They have a unique position and play a complementary role to that of carers and informal caregivers.

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How do plants that move and spread across landscapes become branded as weeds and thereby objects of contention and control? We outline a political ecology approach that builds on a Lefebvrian understanding of the production of space, identifying three scalar moments that make plants into 'weeds' in different spatial contexts and landscapes. The three moments are: the operational scale, which relates to empirical phenomena in nature and society; the observational scale, which defines formal concepts of these phenomena and their implicit or explicit 'biopower' across institutional and spatial categories; and the interpretive scale, which is communicated through stories and actions expressing human feelings or concerns regarding the phenomena and processes of socio-spatial change. Together, these three scalar moments interact to produce a political ecology of landscape transformation, where biophysical and socio-cultural processes of daily life encounter formal categories and modes of control as well as emotive and normative expectations in shaping landscapes. Using three exemplar 'weeds' - acacia, lantana and ambrosia - our political ecology approach to landscape transformations shows that weeds do not act alone and that invasives are not inherently bad organisms. Humans and weeds go together; plants take advantage of spaces and opportunities that we create. Human desires for preserving certain social values in landscapes in contradiction to actual transformations is often at the heart of definitions of and conflicts over weeds or invasives.

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Background Biological rhythmicity has been extensively studied in animals for many decades. Although temporal patterns of physical activity have been identified in humans, no large-scale, multi-national study has been published, and no comparison has been attempted of the ubiquity of activity rhythms at different time scales (such as daily, weekly, monthly, and annual). Methods Using individually worn actigraphy devices, physical activity of 2,328 individuals from five different countries (adults of African descent from Ghana, South Africa, Jamaica, Seychelles, and the United States) was measured for seven consecutive days at different times of the year. Results Analysis for rhythmic patterns identified daily rhythmicity of physical activity in all five of the represented nationalities. Weekly rhythmicity was found in some, but not all, of the nationalities. No significant evidence of lunar rhythmicity or seasonal rhythmicity was found in any of the groups. Conclusions These findings extend previous small-scale observations of daily rhythmicity to a large cohort of individuals from around the world. The findings also confirm the existence of modest weekly rhythmicity but not lunar or seasonal rhythmicity in human activity. These differences in rhythm strength have implications for the management of health hazards of rhythm misalignment. Key Messages Analysis of the pattern of physical activity of 2,328 individuals from five countries revealed strong daily rhythmicity in all five countries, moderate weekly rhythmicity in some countries, and no lunar rhythmicity or seasonal rhythmicity in any of the countries.

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Past studies on the personnel selection demonstrated that a supervisor's advice to discriminate can lead to compliant behaviours. This study had the aim to extend past findings by examining what can overcome the powerful influence of the hierarchy. 50 Swiss managers participated to an in-basket exercise. The main task was to evaluate Swiss candidates (in-group) and foreigners (out-groups: Spanish and Kosovo Albanians) and to select two applicants for a job interview. Main results were the effect of codes of conduct to prevent discrimination against out-group applicants in the presence of a supervisor's advice to prefer in-group members. But, when participants were accountable to an audience, this beneficial effect disappears because participants followed the supervisor's advice. The second aim was to assess if the difference in responses between participants was related to their difference in moral attentiveness. Results showed some significant relationships but not always in the direction expected.

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Division of labour is one of the most prominent features of social insects. The efficient allocation of individuals to different tasks requires dynamic adjustment in response to environmental perturbations. Theoretical models suggest that the colony-level flexibility in responding to external changes and internal perturbation may depend on the within-colony genetic diversity, which is affected by the number of breeding individuals. However, these models have not considered the genetic architecture underlying the propensity of workers to perform the various tasks. Here, we investigated how both within-colony genetic variability (stemming from variation in the number of matings by queens) and the number of genes influencing the stimulus (threshold) for a given task at which workers begin to perform that task jointly influence task allocation efficiency. We used a numerical agent-based model to investigate the situation where workers had to perform either a regulatory task or a foraging task. One hundred generations of artificial selection in populations consisting of 500 colonies revealed that an increased number of matings always improved colony performance, whatever the number of loci encoding the thresholds of the regulatory and foraging tasks. However, the beneficial effect of additional matings was particularly important when the genetic architecture of queens comprised one or a few genes for the foraging task's threshold. By contrast, a higher number of genes encoding the foraging task reduced colony performance with the detrimental effect being stronger when queens had mated with several males. Finally, the number of genes encoding the threshold for the regulatory task only had a minor effect on colony performance. Overall, our numerical experiments support the importance of mating frequency on efficiency of division of labour and also reveal complex interactions between the number of matings and genetic architecture.

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Abstract Life history traits encompass all the decisions concerning fitness an individual is faced with during his life. The study of these traits is crucial to understand the factors shaping the biology of living organisms. Up until now, most of the information on the evolution of life history traits comes from laboratory studies. While these studies are interesting to test the effect of specific parameters, their conclusions are difficult to extrapolate to natural populations. Investigating the evolution of life history traits in natural populations is of great interest. This may be tricky because it requires information on reproduction, survival and morphology of individuals. Mark-recapture methods allow most of this information to be obtained. However, when direct observations of a species are not possible due to its ecology, indirect methods must be used to infer lifetime reproductive success. In this case, molecular markers are particularly helpful in assessing the genetic relationships between individuals and allow the construction of a pedigree. This thesis focuses on a natural population of a small insectivorous mammal, the greater white-toothed shrew, Crocidura russula. Because of its hidden lifestyle, the two complementary techniques mentioned above were combined to gather information on this population. The data were used to explore diverse aspects of evolutionary biology. We demonstrated that the high genetic variance displayed by the species was not maintained by its mating system because this shrew was less monogamous than previously thought. The large genetic diversity was most likely promoted by gene flow from the neighborhood. Dispersal was thus a central topic in this thesis. We showed that dispersal was not driven by inbreeding avoidance. In addition, we did not find any inbreeding depression in the population. Dispersal was promoted by a high number of vacant territories in the population for both sexes, meaning that territory acquisition played an important role in driving dispersal. Moreover, dispersal propensity was shown to have a genetic basis and, once achieved, to have no effect on individual fitness. Body mass was found to be a life history trait strongly influenced by sexual and viability selection in both sexes. Larger individuals had higher access to reproduction through territory acquisition and defense than lighter ones. By contrast, intermediate size individuals were favored by viability selection presumably because of ecological constraints and metabolic costs. Finally, we demonstrated that the majority of the life history traits in our shrew population has the potential to evolve because they maintained substantial amounts of additive genetic variance. Nonetheless, life history traits had no significant heritability due to their high level of nonadditive or environmental variance. Résumé Les traits d'histoire de vie comprennent toutes les décisions auxquelles un individu est confronté au cours de sa vie et qui concernent sa valeur adaptative. L'étude de ces traits est cruciale pour comprendre les facteurs qui façonnent la biologie des êtres vivants. Jusqu'à ce jour, la majorité des informations sur l'évolution des traits d'histoire de vie provient d'études réalisées en laboratoire. Alors que ces études sont intéressantes pour tester l'effet de paramètres spécifiques, leurs conclusions sont difficilement extrapolables aux populations naturelles. Il est particulièrement intéressant d'étudier l'évolution des traits d'histoire de vie dans des populations naturelles. Toutefois, ces études peuvent se révéler difficiles parce qu'elles requièrent des informations sur la reproduction, la survie et la morphologie des individus. Des méthodes de marquage-recapture permettent d'obtenir ces informations. Cependant, lorsque l'écologie de l'espèce rend les obervations directes impossibles, des méthodes indirectes doivent être utilisées pour obtenir le succès reproducteur des individus. Dans ce cas, les marqueurs moléculaires sont particulièrement utiles pour évaluer les relations génétiques entre individus et permettre la construction d'un pedigree. Cette thèse porte sur une population naturelle d'un petit mammifère insectivore, la musaraigne musette, Crocidura russula. Parce que cette espèce présente un mode de vie souterrain, les deux techniques complémentaires mentionnées ci-dessus ont été combinées pour acquérir les informations nécessaires. Les données ont été utilisées pour explorer divers aspects de biologie evolutive. Nous avons montré que la grande quantité de variance génétique trouvée chez cette espèce n'est pas maintenue par son système d'appariement. Celle-ci s'est en effet avérée être moins monogame que ce qui était admis jusqu'ici. Sa grande diversité génétique est plutôt entretenue par le flux de gènes provenant du voisinage. La dispersion a donc été un sujet phare dans cette thèse. Nous avons montré qu'elle n'est pas provoquée par un évitement de la consanguinité et nous n'avons pas trouvé de dépression de consanguité dans notre population. L'acquisition d'un territoire joue par contre un rôle important dans la dispersion. En outre, la dispersion possède une base génétique chez cette espèce. De plus, une fois qu'ils ont dispersé, les individus n'ont pas une valeur adaptative differente d'individus philopatriques. Le poids s'est avéré être un trait d'histoire de vie fortement influencé par la sélection sexuelle et de viabilité chez les deux sexes. Les gros individus ont accès à la reproduction parce qu'ils acquièrent et défendent un territoire plus facilement que les plus légers. Au contraire, les individus de taille intermédiaire sont favorisés par la sélection de viabilité, certainement à cause de contraintes écologiques et de coûts métaboliques. Finalement, nous avons montré que la majorité des traits d'histoire de vie dans notre population a le potentiel d'évoluer parce qu'elle maintient des quantités considérables de variance génétique additive. Néanmoins, l'héritabilité de ces traits d'histoire de vie n'est pas significative à cause de la grande quantité de variance non-additive ou environmentale associée à ces traits.

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CONTENTS: Summary 28 I. Historic background and introduction 29 II. Diversity of cardenolide forms 29 III. Biosynthesis 30 IV. Cardenolide variation among plant parts 31 V. Phylogenetic distribution of cardenolides 32 VI. Geographic distribution of cardenolides 34 VII. Ecological genetics of cardenolide production 34 VIII. Environmental regulation of cardenolide production 34 IX. Biotic induction of cardenolides 36 X. Mode of action and toxicity of cardenolides 38 XI. Direct and indirect effects of cardenolides on specialist and generalist insect herbivores 39 XII. Cardenolides and insect oviposition 39 XIII. Target site insensitivity 40 XIV. Alternative mechanisms of cardenolide resistance 40 XV. Cardenolide sequestration 41 Acknowledgements 42 References 42 SUMMARY: Cardenolides are remarkable steroidal toxins that have become model systems, critical in the development of theories for chemical ecology and coevolution. Because cardenolides inhibit the ubiquitous and essential animal enzyme Na(+) /K(+) -ATPase, most insects that feed on cardenolide-containing plants are highly specialized. With a huge diversity of chemical forms, these secondary metabolites are sporadically distributed across 12 botanical families, but dominate the Apocynaceae where they are found in > 30 genera. Studies over the past decade have demonstrated patterns in the distribution of cardenolides among plant organs, including all tissue types, and across broad geographic gradients within and across species. Cardenolide production has a genetic basis and is subject to natural selection by herbivores. In addition, there is strong evidence for phenotypic plasticity, with the biotic and abiotic environment predictably impacting cardenolide production. Mounting evidence indicates a high degree of specificity in herbivore-induced cardenolides in Asclepias. While herbivores of cardenolide-containing plants often sequester the toxins, are aposematic, and possess several physiological adaptations (including target site insensitivity), there is strong evidence that these specialists are nonetheless negatively impacted by cardenolides. While reviewing both the mechanisms and evolutionary ecology of cardenolide-mediated interactions, we advance novel hypotheses and suggest directions for future work.

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The ability to enter torpor at low ambient temperature, which enables insectivorous bats to survive seasonal food shortage, is often seen as a prerequisite for colonizing cold environments. Free-tailed bats (Molossidae) show a distribution with a maximum latitudinal extension that appears to be intermediate between truly tropical and temperate-zone bat families. We therefore tested the hypothesis that Tadarida teniotis, the molossid species reaching the highest latitude worldwide (46 degrees N), lacks the extreme physiological adaptations to cold that enable other sympatric bats to enter further into the temperate zone. We studied the metabolism of individuals subjected to various ambient temperatures in the laboratory by respirometry, and we monitored the body temperature of free-ranging individuals in winter and early spring in the Swiss Alps using temperature-sensitive radio-tags. For comparison, metabolic data were obtained from Nyctalus noctula, a typically hibernating vespertilionid bat of similar body size and convergent foraging tactics. The metabolic data support the hypothesis that T. teniotis cannot experience such low ambient temperatures as sympatric temperate-zone vespertilionid bats without incurring much higher energetic costs for thermogenesis. The minimum rate of metabolism in torpor was obtained at 7.5 degrees-10 degrees C in T. teniotis, as compared to 2.5 degrees-5 degrees C in N. noctula. Field data showed that T. teniotis behaves as a classic thermo-conforming hibernator in the Alps, with torpor bouts lasting up to 8 d. This contradicts the widely accepted opinion that Molossidae are nonhibernating bars. However, average body temperature (10 degrees-13 degrees C) and mean arousal frequency (3.4 d in one bat in January) appear to be markedly higher than in other temperate-zone bat species. At the northern border of its range T. teniotis selects relatively warm roosts (crevices in tall, south-exposed limestone cliffs) in winter where temperatures oscillate around 10 degrees C. By this means, T. teniotis apparently avoids the risk of prolonged exposure to energetically critical ambient temperatures in torpor (<6.5 degrees-7.5 degrees C) during cold spells. Possibly shared by other Molossidae, the physiological pattern observed in T. teniotis may clearly be linked to the intermediate latitudinal extension of this bat family.

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Sequencing of pools of individuals (Pool-Seq) represents a reliable and cost-effective approach for estimating genome-wide SNP and transposable element insertion frequencies. However, Pool-Seq does not provide direct information on haplotypes so that, for example, obtaining inversion frequencies has not been possible until now. Here, we have developed a new set of diagnostic marker SNPs for seven cosmopolitan inversions in Drosophila melanogaster that can be used to infer inversion frequencies from Pool-Seq data. We applied our novel marker set to Pool-Seq data from an experimental evolution study and from North American and Australian latitudinal clines. In the experimental evolution data, we find evidence that positive selection has driven the frequencies of In(3R)C and In(3R)Mo to increase over time. In the clinal data, we confirm the existence of frequency clines for In(2L)t, In(3L)P and In(3R)Payne in both North America and Australia and detect a previously unknown latitudinal cline for In(3R)Mo in North America. The inversion markers developed here provide a versatile and robust tool for characterizing inversion frequencies and their dynamics in Pool-Seq data from diverse D. melanogaster populations.

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The expression of a social behaviour may affect the fitness of actors and recipients living in the present and in the future of the population. When there is a risk that a future reward will not be experienced in such a context, the value of that reward should be discounted; but by how much? Here, we evaluate social discount rates for delayed fitness rewards to group of recipients living at different positions in both space and time than the actor in a hierarchically clustered population. This is a population where individuals are grouped into families, families into villages, villages into clans, and so on, possibly ad infinitum. The group-wide fitness effects are assumed to either increase or decrease the fecundity or the survival of recipients and can be arbitrarily extended in space and time. We find that actions changing the survival of individuals living in the future are generally more strongly discounted than fecundity-changing actions for all future times and that the value of future rewards increases as individuals live longer. We also find that delayed fitness effects may not only be discounted by a constant factor per unit delay (exponential discounting), but that, as soon as there is localized dispersal in a population, discounting per unit delay is likely to fall rapidly for small delays and then slowly for longer delays (hyperbolic discounting). As dispersal tends to be localized in natural populations, our results suggest that evolution is likely to favour individuals that express present-biased behaviours and that may be time-inconsistent with respect to their group-wide effects.

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Many eukaryote organisms are polyploid. However, despite their importance, evolutionary inference of polyploid origins and modes of inheritance has been limited by a need for analyses of allele segregation at multiple loci using crosses. The increasing availability of sequence data for nonmodel species now allows the application of established approaches for the analysis of genomic data in polyploids. Here, we ask whether approximate Bayesian computation (ABC), applied to realistic traditional and next-generation sequence data, allows correct inference of the evolutionary and demographic history of polyploids. Using simulations, we evaluate the robustness of evolutionary inference by ABC for tetraploid species as a function of the number of individuals and loci sampled, and the presence or absence of an outgroup. We find that ABC adequately retrieves the recent evolutionary history of polyploid species on the basis of both old and new sequencing technologies. The application of ABC to sequence data from diploid and polyploid species of the plant genus Capsella confirms its utility. Our analysis strongly supports an allopolyploid origin of C. bursa-pastoris about 80 000 years ago. This conclusion runs contrary to previous findings based on the same data set but using an alternative approach and is in agreement with recent findings based on whole-genome sequencing. Our results indicate that ABC is a promising and powerful method for revealing the evolution of polyploid species, without the need to attribute alleles to a homeologous chromosome pair. The approach can readily be extended to more complex scenarios involving higher ploidy levels.

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BACKGROUND: Vitamin D deficiency is prevalent in HIV-infected individuals and vitamin D supplementation is proposed according to standard care. This study aimed at characterizing the kinetics of 25(OH)D in a cohort of HIV-infected individuals of European ancestry to better define the influence of genetic and non-genetic factors on 25(OH)D levels. These data were used for the optimization of vitamin D supplementation in order to reach therapeutic targets. METHODS: 1,397 25(OH)D plasma levels and relevant clinical information were collected in 664 participants during medical routine follow-up visits. They were genotyped for 7 SNPs in 4 genes known to be associated with 25(OH)D levels. 25(OH)D concentrations were analysed using a population pharmacokinetic approach. The percentage of individuals with 25(OH)D concentrations within the recommended range of 20-40 ng/ml during 12 months of follow-up and several dosage regimens were evaluated by simulation. RESULTS: A one-compartment model with linear absorption and elimination was used to describe 25(OH)D pharmacokinetics, while integrating endogenous baseline plasma concentrations. Covariate analyses confirmed the effect of seasonality, body mass index, smoking habits, the analytical method, darunavir/ritonavir and the genetic variant in GC (rs2282679) on 25(OH)D concentrations. 11% of the inter-individual variability in 25(OH)D levels was explained by seasonality and other non-genetic covariates, and 1% by genetics. The optimal supplementation for severe vitamin D deficient patients was 300,000 IU two times per year. CONCLUSIONS: This analysis allowed identifying factors associated with 25(OH)D plasma levels in HIV-infected individuals. Improvement of dosage regimen and timing of vitamin D supplementation is proposed based on those results.