Self perceptions as predictors for return to work 2 years after rehabilitation in orthopedic trauma inpatients.

Purpose This study aimed to identify self-perception variables which may predict return to work (RTW) in orthopedic trauma patients 2 years after rehabilitation. Methods A prospective cohort investigated 1,207 orthopedic trauma inpatients, hospitalised in rehabilitation, clinics at admission, discharge, and 2 years after discharge. Information on potential predictors was obtained from self administered questionnaires. Multiple logistic regression models were applied. Results In the final model, a higher likelihood of RTW was predicted by: better general health and lower pain at admission; health and pain improvements during hospitalisation; lower impact of event (IES-R) avoidance behaviour score; higher IES-R hyperarousal score, higher SF-36 mental score and low perceived severity of the injury. Conclusion RTW is not only predicted by perceived health, pain and severity of the accident at the beginning of a rehabilitation program, but also by the changes in pain and health perceptions observed during hospitalisation.

Joint evolution of dispersal and inbreeding load.

Inbreeding avoidance is often invoked to explain observed patterns of dispersal, and theoretical models indeed point to a possibly important role. However, while inbreeding load is usually assumed constant in these models, it is actually bound to vary dynamically under the combined influences of mutation, drift, and selection and thus to evolve jointly with dispersal. Here we report the results of individual-based stochastic simulations allowing such a joint evolution. We show that strongly deleterious mutations should play no significant role, owing to the low genomic mutation rate for such mutations. Mildly deleterious mutations, by contrast, may create enough heterosis to affect the evolution of dispersal as an inbreeding-avoidance mechanism, but only provided that they are also strongly recessive. If slightly recessive, they will spread among demes and accumulate at the metapopulation level, thus contributing to mutational load, but not to heterosis. The resulting loss of viability may then combine with demographic stochasticity to promote population fluctuations, which foster indirect incentives for dispersal. Our simulations suggest that, under biologically realistic parameter values, deleterious mutations have a limited impact on the evolution of dispersal, which on average exceeds by only one-third the values expected from kin-competition avoidance.

A Picture of Performance Goals in the Social Plenum: The Interpersonal Antecedents and Consequences of Performance Goals

Bien que les activités où la compétence est un enjeu (p. ex. : problème académique) prennent souvent place dans des contextes interpersonnels (p. ex. : classe), hiérarchiques (p. ex. : enseignant-e/élèves), et spécifiques en termes de normes et de valeurs (p. ex. : culture), l'étude des buts de performance-le désir de se montrer compétent-e relativement à autrui-a le plus souvent été conduite au seul niveau intrapersonnel. S'appuyant sur le modèle transactionnel du stress et du coping, le modèle circumplexe des comportements interpersonnels, ainsi que sur la théorie de l'élaboration du conflit, la première partie de cette thèse révèle les conséquences interpersonnelles des buts de performance sur la régulation d'un comportement spécifique, à savoir le conflit sociocognitif (c.-à-d., une situation de confrontation avec un intéractant en désaccord) : les buts de performance-approche-le désir d'être meilleur-e qu'autrui-prédisent une régulation du conflit fortement agentique (dominante), soit la validation de son point de vue au détriment de celui de l'intéractant (que nous désignons régulation compétitive) ; alors que les buts de performance-évitement-le désir de ne pas être moins bon-ne qu'autrui-prédisent une régulation du conflit faiblement agentique (soumise), soit l'invalidation de son point de vue au bénéfice de celui de l'intéractant (que nous désignons régulation protective). De plus, les effets susmentionnés augmentent à mesure que l'intéractant est présenté comme supérieurement (vs. similairement) compétent. S'appuyant sur la littérature sur les structures de buts de groupe, et celle sur la socialisation des valeurs, la seconde partie de cette thèse révèle les antécédents interpersonnels des buts de performance, et plus spécifiquement le rôle du superviseur dans la socialisation des buts de performance : les buts de performance-approche d'un superviseur sont positivement associés avec l'émergence au cours du temps des buts de performance-approche de ses subordonnés (particulièrement lorsqu'ils se perçoivent comme compétents) et celle de leurs buts de performance-évitement (particulièrement lorsqu'ils se perçoivent comme incompétents). En outre, ce phénomène consistant en un processus de socialisation, les effets susmentionnés augmentent lorsque l'identification à l'endogroupe des subordonnées augmente, et lorsque l'adhésion aux valeurs culturelles occidentales dominantes (c.-à-d., rehaussement de soi) du superviseur augmente. Dans leur ensemble, ces résultats soulignent la nécessité d'étudier les buts dans leur plenum social, autrement dit, en adoptant une perspective interpersonnelle (c.-à-d., étudier les effets des buts entre les individus), positionnelle (c.-à-d., entre des individus de différentes positions sociales), et idéologique (c.- à-d., entre des individus se conformant à des normes spécifiques et adhérant à des valeurs spécifiques). -- Although competence-relevant activities (e.g., solving an academic problem) are often embedded in interpersonal (e.g., classroom), hierarchical (e.g., teacher/pupils), and norm-/value-specific (e.g., culture) settings, the study of performance goals-the desire to demonstrate competence relative to others-has mostly been conducted at the intrapersonal level alone. Drawing on the transactional model of stress and coping, the circumplex model of interpersonal behaviors, as well as on the conflict elaboration theory, the first part of this thesis reveals the interpersonal consequences of performance goals on the regulation of a specific behavior, namely socio-cognitive conflict (i.e., a situation of confrontation with a disagreeing interactant): Performance-approach goals-the desire to outperform others- predicted a highly agentic (dominant) conflict regulation, that is, the validation of one's point of view at the expense of that of the interactant (which we labeled competitive regulation); whereas performance-avoidance goals-the desire not to be outperformed by others- predicted a poorly agentic (submissive) conflict regulation, that is, the invalidation of one's point of view to the benefit of that of the interactant (which we labeled protective regulation). Furthermore, both the aforementioned effects were found to increase when the interactant was presented as being superiorly (vs. equally) in competence. Drawing on the literature on group goal structure, as well as on research on socialization of supervisors-based values, the second part of this thesis reveals the interpersonal antecedents of performance-based goals endorsement, focusing-more specifically-on the role of group-supervisors in performance goals socialization: Supervisor's performance-approach goals were positively associated with the emergence over time of subordinates' performance-approach (especially when perceiving themselves as competent) and -avoidance goals (especially when perceiving themselves as incompetent). Furthermore, providing evidence that this phenomenon essentially reflects a socialization process, both the aforementioned effects were found to increase as subordinates' in-group identification increased, and as supervisors' adherence to dominant Western values (i.e., self-enhancement values) increased. Taken together, these results advocate the need to study performance goals in their social plenum, that is, adopting an interpersonal (i.e., studying the effects of goals between individuals), positional (i.e., between individuals from different social positions), and ideological (i.e., between individuals following specific norms and endorsing specific values) perspective.

Diagnosis and management of chronic obstructive pulmonary disease: the swiss guidelines: official guidelines of the Swiss Respiratory Society.

The new Swiss Chronic Obstructive Pulmonary Disease (COPD) Guidelines are based on a previous version, which was published 10 years ago. The Swiss Respiratory Society felt the need to update the previous document due to new knowledge and novel therapeutic developments about this prevalent and important disease. The recommendations and statements are based on the available literature, on other national guidelines and, in particular, on the GOLD (Global Initiative for Chronic Obstructive Lung Disease) report. Our aim is to advise pulmonary physicians, general practitioners and other health care workers on the early detection and diagnosis, prevention, best symptomatic control, and avoidance of COPD as well as its complications and deterioration.

Dynamics of the two-dimensional gonihedric spin model

In this paper, we study dynamical aspects of the two-dimensional (2D) gonihedric spin model using both numerical and analytical methods. This spin model has vanishing microscopic surface tension and it actually describes an ensemble of loops living on a 2D surface. The self-avoidance of loops is parametrized by a parameter ¿. The ¿=0 model can be mapped to one of the six-vertex models discussed by Baxter, and it does not have critical behavior. We have found that allowing for ¿¿0 does not lead to critical behavior either. Finite-size effects are rather severe, and in order to understand these effects, a finite-volume calculation for non-self-avoiding loops is presented. This model, like his 3D counterpart, exhibits very slow dynamics, but a careful analysis of dynamical observables reveals nonglassy evolution (unlike its 3D counterpart). We find, also in this ¿=0 case, the law that governs the long-time, low-temperature evolution of the system, through a dual description in terms of defects. A power, rather than logarithmic, law for the approach to equilibrium has been found.

Congenital diaphragmatic hernia: current status and review of the literature.

Treatment of congenital diaphragmatic hernia (CDH) challenges obstetricians, pediatric surgeons, and neonatologists. Persistent pulmonary hypertension (PPHT) associated with lung hypoplasia in CDH leads to a high mortality rate at birth. PPHT is principally due to an increased muscularization of the arterioles. Management of CDH has been greatly improved by the introduction of prenatal surgical intervention with tracheal obstruction (TO) and by more appropriate postnatal care. TO appears to accelerate fetal lung growth and to increase the number of capillary vessels and alveoli. Improvement of postnatal care over the last years is mainly due to the avoidance of lung injury by applying low peak inflation pressure during ventilation. The benefits of other drugs or technical improvements such as the use of inhaled nitric oxide or extracorporeal membrane oxygenation (ECMO) are still being debated and no single strategy is accepted worldwide. Despite intensive clinical and experimental research, the treatment of newborn with CDH remains difficult.

Interventions aiming at balance confidence improvement in older adults: an updated review.

BACKGROUND: Loss of balance confidence is a frequent condition that affects 20-75% of community-dwelling older persons. Although a recent fall is a common trigger, loss of balance confidence also appears independent of previous experience with falls. Maintaining or improving balance confidence is important to avoid unnecessary, self-imposed restrictions of activity and subsequent disability. Holding another person's hand or using an assistive device while walking are simple interventions that are used naturally to address poor balance confidence in daily life. However, more complex interventions have also been developed and tested to achieve more sustained improvement in balance confidence. OBJECTIVES: This review describes interventions that have been tested to improve balance confidence in older community-dwelling persons. METHODS: Based on 2 recent systematic reviews, an additional search for literature was performed to update current information on interventions aiming at balance confidence improvement. Interventions were classified as those directly aimed at increasing balance confidence or not, and further stratified into those using monofactorial or multifactorial approaches. RESULTS: A total of 46 randomized controlled trials were identified. Five of the 8 interventions that directly targeted balance confidence showed benefits. Among those, multicomponent behavioral group interventions provided the most robust evidence of benefits in improving balance confidence and in decreasing activity avoidance. Among interventions not directly aiming at balance confidence improvement (11/21 studies with benefits), exercise (including tai chi) appears as the most promising monofactorial intervention. Nine of the 17 multifactorial fall prevention programs showed an effect on balance confidence, exercise being a main component in 7 of these 9 studies. Interventions that targeted elderly persons reporting poor balance confidence and/or those at risk for falls seemed more likely to be beneficial. CONCLUSIONS: Positive and sometimes sustained improvement in balance confidence can be achieved by various interventions among community-dwelling elderly persons. The effect of these interventions on activity restriction associated with poor balance confidence have been less well studied, but some studies also suggest potential benefits.

Social Investment Policies in Times of Permanent Austerity

The objective of this paper is to identify the political conditions that are most likely to be conducive to the development of social investment policies. It starts from the view put forward by theorists of welfare retrenchment that in the current context of permanent austerity, policy is likely to be dominated by retrenchment and implemented in a way that allows governments to minimise the risk of electoral punishment (blame avoidance). It is argued that this view is inconsistent with developments observed in several European countries, were some welfare state expansion has taken place mostly in the fields of childcare and active labour market policy. An alternative model is put forward, that emphasises the notion of "affordable credit claiming". It is argued that even under strong budgetary pressures, governments maintain a preference for policies that allow them to claim credit for their actions. Since the traditional redistributive policies tend to be off the menu for cost reasons, governments have tended to favour investments in childcare and active labour market policy as credit claiming tools. Policies developed in this way while they have a social investment flavour, tend to be rather limited in the extent to which they genuinely improve prospects of disadvantaged people by investing in their human capital. A more ambitious strategy of social investment sees unlikely to develop on the basis of affordable credit claiming. The paper starts by presenting the theoretical argument, which is then illustrated with examples taken from European countries both in the pre-crisis and in the post-crisis years.

Genomewide association study of atazanavir pharmacokinetics and hyperbilirubinemia in AIDS Clinical Trials Group protocol A5202.

BACKGROUND: Atazanavir-associated hyperbilirubinemia can cause premature discontinuation of atazanavir and avoidance of its initial prescription. We used genomewide genotyping and clinical data to characterize determinants of atazanavir pharmacokinetics and hyperbilirubinemia in AIDS Clinical Trials Group protocol A5202. METHODS: Plasma atazanavir pharmacokinetics and indirect bilirubin concentrations were characterized in HIV-1-infected patients randomized to atazanavir/ritonavir-containing regimens. A subset had genomewide genotype data available. RESULTS: Genomewide assay data were available from 542 participants, of whom 475 also had data on estimated atazanavir clearance and relevant covariates available. Peak bilirubin concentration and relevant covariates were available for 443 participants. By multivariate analysis, higher peak on-treatment bilirubin levels were found to be associated with the UGT1A1 rs887829 T allele (P=6.4×10), higher baseline hemoglobin levels (P=4.9×10), higher baseline bilirubin levels (P=6.7×10), and slower plasma atazanavir clearance (P=8.6×10). For peak bilirubin levels greater than 3.0 mg/dl, the positive predictive value of a baseline bilirubin level of 0.5 mg/dl or higher with hemoglobin concentrations of 14 g/dl or higher was 0.51, which increased to 0.85 with rs887829 TT homozygosity. For peak bilirubin levels of 3.0 mg/dl or lower, the positive predictive value of a baseline bilirubin level less than 0.5 mg/dl with a hemoglobin concentration less than 14 g/dl was 0.91, which increased to 0.96 with rs887829 CC homozygosity. No polymorphism predicted atazanavir pharmacokinetics at genomewide significance. CONCLUSION: Atazanavir-associated hyperbilirubinemia is best predicted by considering UGT1A1 genotype, baseline bilirubin level, and baseline hemoglobin level in combination. Use of ritonavir as a pharmacokinetic enhancer may have abrogated genetic associations with atazanavir pharmacokinetics.

The genetic structure of metapopulations and conservation biology.

A range of models describing metapopulations is surveyed and their implications for conservation biology are described. An overview of the use of both population genetic elements and demographic theory in metapopulation models is given. It would appear that most of the current models suffer from either the use of over-simplified demography or the avoidance of selectively important genetic factors. The scale for which predictions are made by the various models is often obscure. A conceptual framework for describing metapopulations by utilising the concept of fitness of local populations is provided and some examples are given. The expectation that any general theory, such as that of metapopulations, can make useful predictions for particular problems of conservation is examined and compared with the prevailing 'state of the art' recommendations.

Sex-specific estimates of dispersal show female philopatry and male dispersal in a promiscuous amphibian, the alpine salamander (Salamandra atra).

Amphibians display wide variations in life-history traits and life cycles that should prove useful to explore the evolution of sex-biased dispersal, but quantitative data on sex-specific dispersal patterns are scarce. Here, we focused on Salamandra atra, an endemic alpine species showing peculiar life-history traits. Strictly terrestrial and viviparous, the species has a promiscuous mating system, and females reproduce only every 3 to 4 years. In the present study, we provide quantitative estimates of asymmetries in male vs. female dispersal using both field-based (mark-recapture) and genetic approaches (detection of sex-biased dispersal and estimates of migration rates based on the contrast in genetic structure across sexes and age classes). Our results revealed a high level of gene flow among populations, which stems exclusively from male dispersal. We hypothesize that philopatric females benefit from being familiar with their natal area for the acquisition and defence of an appropriate shelter, while male dispersal has been secondarily favoured by inbreeding avoidance. Together with other studies on amphibians, our results indicate that a species' mating system alone is a poor predictor of sex-linked differences in dispersal, in particular for promiscuous species. Further studies should focus more directly on the proximate forces that favour or limit dispersal to refine our understanding of the evolution of sex-biased dispersal in animals.

Mechanosensory interactions drive collective behaviour in Drosophila.

Collective behaviour enhances environmental sensing and decision-making in groups of animals. Experimental and theoretical investigations of schooling fish, flocking birds and human crowds have demonstrated that simple interactions between individuals can explain emergent group dynamics. These findings indicate the existence of neural circuits that support distributed behaviours, but the molecular and cellular identities of relevant sensory pathways are unknown. Here we show that Drosophila melanogaster exhibits collective responses to an aversive odour: individual flies weakly avoid the stimulus, but groups show enhanced escape reactions. Using high-resolution behavioural tracking, computational simulations, genetic perturbations, neural silencing and optogenetic activation we demonstrate that this collective odour avoidance arises from cascades of appendage touch interactions between pairs of flies. Inter-fly touch sensing and collective behaviour require the activity of distal leg mechanosensory sensilla neurons and the mechanosensory channel NOMPC. Remarkably, through these inter-fly encounters, wild-type flies can elicit avoidance behaviour in mutant animals that cannot sense the odour--a basic form of communication. Our data highlight the unexpected importance of social context in the sensory responses of a solitary species and open the door to a neural-circuit-level understanding of collective behaviour in animal groups.

On the industry experience premium and labor mobility

[cat] Hi ha evidència que l'experiència es remunera diferentment segons la indústria. Proposem un model teòric que explica aquestes diferències. Suposem que la mobilitat de treballadors aporta coneixement extern a l'empresa i això augmenta la seva productivitat. Els resultats mostren que l'experiència és millor remunerada en les indústries amb costos de mobilitat baixos, amb molt aprenentatge (learning-by-doing) i alt nivell tecnològic. A més, trobem una relació en forma de U entre la remuneració de l'experiència i el nivell d'absorció de coneixement extern, la substitutibilitat entre diferents tipus de treballadors i la varietat de coneixement dins la indústria. Els resultats són consistents amb l'evidència que les indústries intensives en I and D remuneren millor l'experiència.

Psychophysiological responses to affective pictures in younger and older adults

Despite the central role that emotional reactivity plays in adaptation, few studies have examined age differences in this capacity under well-controlled laboratory conditions, on the basis of standardized emotion-evoking stimuli and assessing experiential, expressive, and physiological measures. 212 adults ranging in age from 20 to 81 years were exposed to 14 picture series, each lasting 60 s and of a different valence and arousal. We assessed valence and arousal ratings, cardiovascular, respiratory and electrodermalmeasures, facial muscle activity and gaze activity. Here, we present findings for 22 younger (mean age=24.0) and 22 older (mean age=72.1) adults for valence and arousal ratings, systolic bloodpressure (SBP) andheart rate (HR).Compared to younger adults, older adults rated unpleasant seriesmore negatively and showed a smaller range in arousal for pleasant series. SBP linearly increased with increasing appetitive activation. HR showed the expected deceleration from the pleasant to the unpleasant series.However, this effect was clearer for the younger adults than the older adults. For older adults, if something is pleasant, it is also judged to be generally lower in arousal, whereas, if something is unpleasant, it is also judged to be generally higher in arousal. The results for SBP indicate that the association between arousal and sympathetic outflow to the cardiovascular system might be similar in younger and older adults. The results for HR suggest that the parasympathetic activation might be attenuated in older adults as compared to younger adults.

Natural variation in learning ability in "Drosophila melanogaster"

Learning is the ability of an organism to adapt to the changes of its environment in response to its past experience. It is a widespread ability in the animal kingdom, but its evolutionary aspects are poorly known. Learning ability is supposedly advantageous under some conditions, when environmental conditions are not too stable - because in this case there is no need to learn to predict any event in the environment - and not changing too fast - otherwise environmental cues cannot be used because they are not reliable. Nevertheless, learning ability is also known to be costly in terms of energy needed for neuronal synthesis, memory formation, initial mistakes. During my PhD, I focused on the study of genetic variability of learning ability in natural populations. Genetic variability is the basis on which natural selection and genetic drift can act. How does learning ability vary in nature? What are the roles of additive genetic variation or maternal effects in this variation? Is it involved in evolutionary trade-offs with other fitness-related traits?¦I investigated a natural population of fruit fly, Drosophila melanogaster, as a model organism. Its learning ability is easy to measure with associative memory tests. I used two research tools: multiple inbred and isofemale lines derived from a natural population as a representative sample. My work was divided into three parts.¦First, I investigated the effects of inbreeding on aversive learning (avoidance of an odor previously associated with mechanical shock). While the inbred lines consistently showed reduced egg-to-adult viability by 28 %, the effects of inbreeding on learning performance was 18 % and varied among assays, with a trend to be most pronounced for intermediate conditioning intensity. Variation among inbred lines indicates that ample genetic variance for learning was segregating in the base population, and suggests that the inbreeding depression observed in learning performance was mostly due to dominance rather than overdominance. Across the inbred lines, learning performance was positively correlated with the egg-to-adult viability. This positive genetic correlation contradicts previous studies which observed a trade-off between learning ability and lifespan or larval competitive ability. It suggests that much of the genetic variation for learning is due to pleiotropic effects of genes affecting other functions related to survival. Together with the overall mild effects of inbreeding on learning performance, this suggests that genetic variation specifically affecting learning is either very low, or is due to alleles with mostly additive (semi-dominant) effects. It also suggests that alleles reducing learning performance are on average partially recessive, because their effect does not appear in the outbred base population. Moreover, overdominance seems unlikely as major cause of the inbreeding depression, because even if the overall mean of the inbred line is smaller than the outbred base population, some of the inbred lines show the same learning score as the outbred base population. If overdominance played an important part in inbreeding depression, then all the homozygous lines should show lower learning ability than¦outbred base population.¦In the second part of my project, I sampled the same natural population again and derived isofemale lines (F=0.25) which are less adapted to laboratory conditions and therefore are more representative of the variance of the natural population. They also showed some genetic variability for learning, and for three other fitness-related traits possibly related with learning: resistance to bacterial infection, egg-to-adult viability and developmental time. Nevertheless, the genetic variance of learning ability did not appear to be smaller than the variance of the other traits. The positive correlation previously observed between learning ability and egg- to-adult viability did not appear in isofemale lines (nor a negative correlation). It suggests that there was still genetic variability within isofemale lines and that they did not fix the highly deleterious pleiotropic alleles possibly responsible for the previous correlation.¦In order to investigate the relative amount of nuclear (additive and non-additive effects) and extra-nuclear (maternal and paternal effect) components of variance in learning ability and other fitness-related traits among the inbred lines tested in part one, I performed a diallel cross between them. The nuclear additive genetic variance was higher than other components for learning ability and survival to learning ability, but in contrast, maternal effects were more variable than other effects for developmental traits. This suggests that maternal effects, which reflects effects from mitochondrial DNA, epigenetic effects, or the amount of nutrients that are invested by the mother in the egg, are more important in the early stage of life, and less at the adult stage. There was no additive genetic correlation between learning ability and other traits, indicating that the correlation between learning ability and egg-to-adult viability observed in the first pat of my project was mostly due to recessive genes.¦Finally, my results showed that learning ability is genetically variable. The diallel experiment showed additive genetic variance was the most important component of the total variance. Moreover, every inbred or isofemale line showed some learning ability. This suggested that alleles impairing learning ability are eliminated by selection, and therefore that learning ability is under strong selection in natural populations of Drosophila. My results cannot alone explain the maintenance of the observed genetic variation. Even if I cannot eliminate the hypothesis of pleiotropy between learning ability and the other fitness-related traits I measured, there is no evidence for any trade-off between these traits and learning ability. This contradicts what has been observed between learning ability and other traits like lifespan and larval competitivity.¦L'apprentissage représente la capacité d'un organisme à s'adapter aux changement de son environnement au cours de sa vie, en réponse à son expérience passée. C'est une capacité très répandue dans le règne animal, y compris pour les animaux les plus petits et les plus simples, mais les aspects évolutifs de l'apprentissage sont encore mal connus. L'apprentissage est supposé avantageux dans certaines conditions, quand l'environnement n'est ni trop stable - dans ce cas, il n'y a rien à apprendre - ni trop variable - dans ce cas, les indices sur lesquels se reposer changent trop vite pour apprendre. D'un autre côté, l'apprentissage a aussi des coûts, en terme de synthèse neuronale, pour la formation de la mémoire, ou de coûts d'erreur initiale d'apprentissage. Pendant ma thèse, j'ai étudié la variabilité génétique naturelle des capacités d'apprentissage. Comment varient les capacités d'apprentissage dans la nature ? Quelle est la part de variation additive, l'impact des effets maternel ? Est-ce que l'apprentissage est impliqué dans des interactions, de type compromis évolutifs, avec d'autres traits liés à la fitness ?¦Afin de répondre à ces questions, je me suis intéressée à la mouche du vinaigre, ou drosophile, un organisme modèle. Ses capacités d'apprentissage sont facile à étudier avec un test de mémoire reposant sur l'association entre un choc mécanique et une odeur. Pour étudier ses capacités naturelles, j'ai dérivé de types de lignées d'une population naturelle: des lignées consanguines et des lignées isofemelles.¦Dans une première partie, je me suis intéressée aux effets de la consanguinité sur les capacités d'apprentissage, qui sont peu connues. Alors que les lignées consanguines ont montré une réduction de 28% de leur viabilité (proportion d'adultes émergeants d'un nombre d'oeufs donnés), leurs capacités d'apprentissage n'ont été réduites que de 18%, la plus forte diminution étant obtenue pour un conditionnement modéré. En outre, j'ai également observé que les capacités d'apprentissage était positivement corrélée à la viabilité entre les lignées. Cette corrélation est surprenante car elle est en contradiction avec les résultats obtenus par d'autres études, qui montrent l'existence de compromis évolutifs entre les capacités d'apprentissage et d'autres traits comme le vieillissement ou la compétitivité larvaire. Elle suggère que la variation génétique des capacités d'apprentissage est due aux effets pleiotropes de gènes récessifs affectant d'autres fonctions liées à la survie. Ces résultats indiquent que la variation pour les capacités d'apprentissage est réduite comparée à celle d'autres traits ou est due à des allèles principalement récessifs. L'hypothèse de superdominance semble peu vraisemblable, car certaines des lignées consanguines ont obtenu des scores d'apprentissage égaux à ceux de la population non consanguine, alors qu'en cas de superdominance, elles auraient toutes dû obtenir des scores inférieurs.¦Dans la deuxième partie de mon projet, j'ai mesuré les capacités d'apprentissage de lignées isofemelles issues de la même population initiale que les lignées consanguines. Ces lignées sont issues chacune d'un seul couple, ce qui leur donne un taux d'hétérozygosité supérieur et évite l'élimination de lignées par fixation d'allèles délétères rares. Elles sont ainsi plus représentatives de la variabilité naturelle. Leur variabilité génétique est significative pour les capacités d'apprentissage, et trois traits liés à la fois à la fitness et à l'apprentissage: la viabilité, la résistance à l'infection bactérienne et la vitesse de développement. Cependant, la variabilité des capacités d'apprentissage n'apparaît cette fois pas inférieure à celle des autres traits et aucune corrélation n'est constatée entre les capacité d'apprentissage et les autres traits. Ceci suggère que la corrélation observée auparavant était surtout due à la fixation d'allèles récessifs délétères également responsables de la dépression de consanguinité.¦Durant la troisième partie de mon projet, je me suis penchée sur la décomposition de la variance observée entre les lignées consanguines observée en partie 1. Quatre composants ont été examinés: la variance due à des effets nucléaires (additifs et non additifs), et due à des effets parentaux (maternels et paternels). J'ai réalisé un croisement diallèle de toutes les lignées. La variance additive nucléaire s'est révélée supérieure aux autres composants pour les capacités d'apprentissage et la résistance à l'infection bactérienne. Par contre, les effets maternels étaient plus importants que les autres composants pour les traits développementaux (viabilité et vitesse de développement). Ceci suggère que les effets maternels, dus à G ADN mitochondrial, à l'épistasie ou à la quantité de nutriments investis dans l'oeuf par la mère, sont plus importants dans les premiers stades de développement et que leur effet s'estompe à l'âge adulte. Il n'y a en revanche pas de corrélation statistiquement significative entre les effets additifs des capacités d'apprentissage et des autres traits, ce qui indique encore une fois que la corrélation observée entre les capacités d'apprentissage et la viabilité dans la première partie du projet était due à des effets d'allèles partiellement récessifs.¦Au, final, mes résultats montrent bien l'existence d'une variabilité génétique pour les capacités d'apprentissage, et l'expérience du diallèle montre que la variance additive de cette capacité est importante, ce qui permet une réponse à la sélection naturelle. Toutes les lignées, consanguines ou isofemelles, ont obtenu des scores d'apprentissage supérieurs à zéro. Ceci suggère que les allèles supprimant les capacités d'apprentissage sont fortement contre-sélectionnés dans la nature Néanmoins, mes résultats ne peuvent pas expliquer le maintien de cette variabilité génétique par eux-même. Même si l'hypothèse de pléiotropie entre les capacités d'apprentissage et l'un des traits liés à la fitness que j'ai mesuré ne peut être éliminée, il n'y a aucune preuve d'un compromis évolutif pouvant contribuer au maintien de la variabilité.