939 resultados para Discoveries in geography


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Natural selection drives local adaptation, potentially even at small temporal and spatial scales. As a result, adaptive genetic and phenotypic divergence can occur among populations living in different habitats. We investigated patterns of differentiation between contrasting lake and stream habitats in the cyprinid fish European minnow (Phoxinus phoxinus) at both the morphological and genomic levels using geometric morphometrics and AFLP markers, respectively. We also used a spatial correlative approach to identify AFLP loci associated with environmental variables representing potential selective forces responsible for adaptation to divergent habitats. Our results identified different morphologies between lakes and streams, with lake fish presenting a deeper body and caudal peduncle compared to stream fish. Body shape variation conformed to a priori predictions concerning biomechanics and swimming performance in lakes vs. streams. Moreover, morphological differentiation was found to be associated with several environmental variables, which could impose selection on body and caudal peduncle shape. We found adaptive genetic divergence between these contrasting habitats in the form of 'outlier' loci (2.9%) whose genetic divergence exceeded neutral expectations. We also detected additional loci (6.6%) not associated with habitat type (lake vs. stream), but contributing to genetic divergence between populations. Specific environmental variables related to trophic dynamics, landscape topography and geography were associated with several neutral and outlier loci. These results provide new insights into the morphological divergence and genetic basis of adaptation to differentiated habitats.

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Ecological parameters vary in space, and the resulting heterogeneity of selective forces can drive adaptive population divergence. Clinal variation represents a classical model to study the interplay of gene flow and selection in the dynamics of this local adaptation process. Although geographic variation in phenotypic traits in discrete populations could be remainders of past adaptation, maintenance of adaptive clinal variation requires recurrent selection. Clinal variation in genetically determined traits is generally attributed to adaptation of different genotypes to local conditions along an environmental gradient, although it can as well arise from neutral processes. Here, we investigated whether selection accounts for the strong clinal variation observed in a highly heritable pheomelanin-based color trait in the European barn owl by comparing spatial differentiation of color and of neutral genes among populations. Barn owl's coloration varies continuously from white in southwestern Europe to reddish-brown in northeastern Europe. A very low differentiation at neutral genetic markers suggests that substantial gene flow occurs among populations. The persistence of pronounced color differentiation despite this strong gene flow is consistent with the hypothesis that selection is the primary force maintaining color variation among European populations. Therefore, the color cline is most likely the result of local adaptation.

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The disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), has caused dramatic amphibian population declines and extinctions in Australia, Central and North America, and Europe. Bd is associated with >200 species extinctions of amphibians, but not all species that become infected are susceptible to the disease. Specifically, Bd has rapidly emerged in some areas of the world, such as in Australia, USA, and throughout Central and South America, causing population and species collapse. The mechanism behind the rapid global emergence of the disease is poorly understood, in part due to an incomplete picture of the global distribution of Bd. At present, there is a considerable amount of geographic bias in survey effort for Bd, with Asia being the most neglected continent. To date, Bd surveys have been published for few Asian countries, and infected amphibians have been reported only from Indonesia, South Korea, China and Japan. Thus far, there have been no substantiated reports of enigmatic or suspected disease-caused population declines of the kind that has been attributed to Bd in other areas. In order to gain a more detailed picture of the distribution of Bd in Asia, we undertook a widespread, opportunistic survey of over 3,000 amphibians for Bd throughout Asia and adjoining Papua New Guinea. Survey sites spanned 15 countries, approximately 36° latitude, 111° longitude, and over 2000 m in elevation. Bd prevalence was very low throughout our survey area (2.35% overall) and infected animals were not clumped as would be expected in epizootic events. This suggests that Bd is either newly emerging in Asia, endemic at low prevalence, or that some other ecological factor is preventing Bd from fully invading Asian amphibians. The current observed pattern in Asia differs from that in many other parts of the world.

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GENDER EMPOWERMENT: EFFECTS OF GODS, GEOGRAPHY, AND GDP¦Fenley, M., & Antonakis, J.¦ABSTRACT¦We examined the determinants of women's empowerment in the economy and political leadership in 178 countries. Given the androcentric nature of most religions, we hypothesized that high degrees of country-level theistic belief create social conditions that impede the progression of women to power. The dependent variable was the Gender Empowerment index of the United Nations Development Program, which captures the participation of women in political leadership, management, and their share of national income. Controlling for GDP per capita as well as the fixed-effects of the dominant type of religion and legal origin and instrumenting all endogenous variables with geographic or historical variables, our results show that atheism has a significant positive effect on gender empowerment. These results are driven by the rule of law, which in addition to being a catalyst for economic development, appears to crowd-out the informal regulation of behavior due to religious norms.¦DEVELOPING WOMEN LEADERS: COMPARING A TRANSFORMATIONAL AND A CHARISMATIC LEADERSHIP INTERVENTION¦Fenley, M., Jacquart, P., & Antonakis, J.¦ABSTRACT¦Along with a gender imbalance in leadership role occupancy, most leadership interventions have been conducted with samples of men. We conducted an experiment wherein we assigned female participants (n = 38, mean age = 35 years) to one of two conditions: Transformational (i.e., "standard") leadership training or charismatic leadership training. The two interventions were essentially equivalent, except that we also focused on developing the "charismatic leadership tactics" (e.g., rhetorical skills) of participants in the charismatic condition. After the interventions, we randomly assigned participants into problem-solving teams that required extensive interaction. Each team had an equal number of participants having received transformational training or charismatic training. At the end of the team exercises, participants rated each of their team members on a leadership prototypicality measure. Results indicated that those who received charismatic training scored higher (a) on prototypicality (standardized  = .42) and (b) on a test of declarative knowledge of charismatic rhetorical strategies (i.e., a manipulation check, standardized  = .76). Furthermore, the score on the test fully mediated the effect of the treatment on prototypicality (standardized indirect  = .32). We discuss the importance and practical implications of these results.¦CHANGING ATTITUDES TOWARDS WOMEN IN A MALE SEX-TYPE WORK ENVIRONMENT: EVIDENCE FROM A FIELD EXPERIMENT IN EUROPEAN ATHLETICS¦Fenley, M.¦ABSTRACT¦Most sports organizations have a similar gender gap in leadership as do the majority of non-sport organizations. Women's careers sputter somewhere at coaching level positions and few women obtain top leadership positions. Greater awareness of gender inequalities in general, and in leadership in particular, could decrease gender discrimination and increase women's presence at upper levels. The goal of this study was to evaluate the impact of an intervention using an online gender awareness exercise. Participants (n = 1,001 participants, n = 32 countries) were randomly assigned to one of eight conditions in a 2 (a discriminating perspective-taking story or a non-discriminating perspective-taking story) by 2 (gender quiz or no gender quiz) by 2 (diversity quiz or no diversity quiz) factorial design. The results show that the online perspective taking exercise changed initial sexist attitudes. Participants having taken a diversity quiz had less sexist attitudes (as measured by the Modern- and Old-fashioned sexism scale) than did participants who did not take the diversity quiz (irrespective of perspective-taking story). The combination of having taken a diversity quiz with a gender quiz had the biggest impact on attitudes for the non-discriminating story.

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BACKGROUND AND AIMS: Black cherry (Prunus serotina) is a North American tree that is rapidly invading European forests. This species was introduced first as an ornamental plant, then it was massively planted by foresters in many countries, but its origins and the process of invasion remain poorly documented. Based on a genetic survey of both native and invasive ranges, the invasion history of black cherry was investigated by identifying putative source populations and then assessing the importance of multiple introductions on the maintenance of gene diversity. METHODS: Genetic variability and structure of 23 populations from the invasive range and 22 populations from the native range were analysed using eight nuclear microsatellite loci and five chloroplast DNA regions. KEY RESULTS: Chloroplast DNA diversity suggests there were multiple introductions from a single geographic region (the north-eastern United States). A low reduction of genetic diversity was observed in the invasive range for both nuclear and plastid genomes. High propagule pressure including both the size and number of introductions shaped the genetic structure in Europe and boosted genetic diversity. Populations from Denmark, The Netherlands, Belgium and Germany showed high genetic diversity and low differentiation among populations, supporting the hypothesis that numerous introduction events, including multiple individuals and exchanges between sites, have taken place during two centuries of plantation. CONCLUSIONS: This study postulates that the invasive black cherry has originated from east of the Appalachian Mountains (mainly the Allegheny plateau) and its invasiveness in north-western Europe is mainly due to multiple introductions containing high numbers of individuals.

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The treatment of stage IV melanoma has been revolutionized over the last years with the development of immunotherapies that, for the first time, have shown a significant benefit in overall survival, as well as with extremely effective targeted therapies, that also led to improved survival. These results are the fruits of an important translational research effort that allowed a rational approach with a very fast clinical development. The treatment of metastatic melanoma is, therefore, an illustration of the new paradigms of modern molecular research in oncology. In this review, we will present the various agents that have made the proof of their clinical benefit, as well as the scientific discoveries that allowed their development. Some of the remaining questions will be touched upon with the ongoing clinical trials. Inclusion of patients in these studies remains the top priority to improve on the clinical care.

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BACKGROUND: Previous studies on childhood cancer and nuclear power plants (NPPs) produced conflicting results. We used a cohort approach to examine whether residence near NPPs was associated with leukaemia or any childhood cancer in Switzerland. METHODS: We computed person-years at risk for children aged 0-15 years born in Switzerland from 1985 to 2009, based on the Swiss censuses 1990 and 2000 and identified cancer cases from the Swiss Childhood Cancer Registry. We geo-coded place of residence at birth and calculated incidence rate ratios (IRRs) with 95% confidence intervals (CIs) comparing the risk of cancer in children born <5 km, 5-10 km and 10-15 km from the nearest NPP with children born >15 km away, using Poisson regression models. RESULTS: We included 2925 children diagnosed with cancer during 21 117 524 person-years of follow-up; 953 (32.6%) had leukaemia. Eight and 12 children diagnosed with leukaemia at ages 0-4 and 0-15 years, and 18 and 31 children diagnosed with any cancer were born <5 km from a NPP. Compared with children born >15 km away, the IRRs (95% CI) for leukaemia in 0-4 and 0-15 year olds were 1.20 (0.60-2.41) and 1.05 (0.60-1.86), respectively. For any cancer, corresponding IRRs were 0.97 (0.61-1.54) and 0.89 (0.63-1.27). There was no evidence of a dose-response relationship with distance (P > 0.30). Results were similar for residence at diagnosis and at birth, and when adjusted for potential confounders. Results from sensitivity analyses were consistent with main results. CONCLUSIONS: This nationwide cohort study found little evidence of an association between residence near NPPs and the risk of leukaemia or any childhood cancer.

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Determining the biogeographical histories of rainforests is central to our understanding of the present distribution of tropical biodiversity. Ice age fragmentation of central African rainforests strongly influenced species distributions. Elevated areas characterized by higher species richness and endemism have been postulated to be Pleistocene forest refugia. However, it is often difficult to separate the effects of history and of present-day ecological conditions on diversity patterns at the interspecific level. Intraspecific genetic variation could yield new insights into history, because refugia hypotheses predict patterns not expected on the basis of contemporary environmental dynamics. Here, we test geographically explicit hypotheses of vicariance associated with the presence of putative refugia and provide clues about their location. We intensively sampled populations of Aucoumea klaineana, a forest tree sensitive to forest fragmentation, throughout its geographical range. Characterizing variation at 10 nuclear microsatellite loci, we were able to obtain phylogeographic data of unprecedented detail for this region. Using Bayesian clustering approaches, we demonstrated the presence of four differentiated genetic units. Their distribution matched that of forest refugia postulated from patterns of species richness and endemism. Our data also show differences in diversity dynamics at leading and trailing edges of the species' shifting distribution. Our results confirm predictions based on refugia hypotheses and cannot be explained on the basis of present-day ecological conditions.

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The treatment of stage IV melanoma has witnessed a very impressive pace of innovation in recent years, to a point where the management of these patients has very little in common to what was standard practice 5 years ago. If the gain in overall survival, the high response rates or the induction of a significant fraction of long survivors are all very exciting news for our patients and their families, the path that led to these discoveries is as important. Rather than empirical, the development of these new strategies has been extremely rational, based on state-of-the-art basic biology and immunology, exemplary translational research and, finally, hypothesis-driven targeted trials that led to rapid approval. In this review, we will cover all the new targeted therapies that have emerged as the results of these translational programs, focusing mainly on signaling pathway- and immune checkpoint-targeted therapies. Taken collectively, these new developments set the bar for a new paradigm in future translational and clinical research in both melanoma as well as other tumor types.

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AimOur aim was to understand the interplay of heterogeneous climatic and spatial landscapes in shaping the distribution of nuclear microsatellite variation in burrowing parrots, Cyanoliseus patagonus. Given the marked phenotypic differences between populations of burrowing parrots we hypothesized an important role of geographical as well climatic heterogeneity in the population structure of this species. LocationSouthern South America. MethodsWe applied a landscape genetics approach to investigate the explicit patterns of genetic spatial autocorrelation based on both geography and climate using spatial principal component analysis (sPCA). This necessitated a novel statistical estimation of the species climatic landscape, considering temperature- and precipitation-based variables separately to evaluate their weight in shaping the distribution of genetic variation in our model system. ResultsGeographical and climatic heterogeneity successfully explained molecular variance in burrowing parrots. sPCA divided the species distribution into two main areas, Patagonia and the pre-Andes, which were connected by an area of geographical and climatic transition. Moreover, sPCA revealed cryptic and conservation-relevant genetic structure: the pre-Andean populations and the transition localities were each divided into two groups, each management units for conservation. Main conclusionssPCA, a method originally developed for spatial genetics, allowed us to unravel the genetic structure related to spatial and climatic landscapes and to visualize these patterns in landscape space. These novel climatic inferences underscore the importance of our modified sPCA approach in revealing how climatic variables can drive cryptic patterns of genetic structure, making the approach potentially useful in the study of any species distributed over a climatically heterogeneous landscape.

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The reversal of congenital hypogonadotropic hypogonadism (CHH) is a relatively recent phenomenon that has gained increasing attention over the past 10 years. Yet to date, only one prospective study has been conducted estimating that 10% (95% confidence interval [CI]: 2%-18%) of cases undergo reversal. [1] Other retrospective studies have reported rates in the range of 5%-8% [2],[3] and a recent study showed 44/308 (14%, 95% CI: 11%-19%) CHH patients underwent reversal. [4] Moreover, a time-to-event analysis in this large cohort revealed a lifetime reversal incidence of 22%. The article by Mao and colleagues presented in this issue is a meaningful contribution to our understanding of reversal as it examines the largest retrospective cohort to date. [5] Interestingly, they report the rate of reversal as 5% (95% CI: 3%-8%) in this Chinese cohort. It is difficult to reconcile the discrepancies in rates of reversibility and direct comparisons are hampered by the variable definitions employed. Using a novel definition for reversal (i.e, either endogenous testosterone (T) >270 ng dl−1 , serum T gradually increasing above 150 ng dl−1 with increased testicular volume, or normal spontaneous sperm production/normal erectile function/ejaculation), Mao and colleagues posit that testicular size and triptorelin-stimulated LH levels are reliable predictive factors for reversal. However, these cannot be considered as hard and fast rules for predicting reversal as the groups intersect - akin to the overlap observed between CHH patients and those with delayed puberty. Indeed, the fact that approximately half (44%, 95% CI: 25%-66%) of the reversal patients in the study by Mao et al.[5] were diagnosed between 17 and 19 years of age, underscores the challenge in differentiating CHH from extreme normal variants of puberty. This study further lends credence the recently reported observations that reversals may relapse. [4],[6] The notion that reversal may not be lasting highlights the vulnerability of the reproductive axis among CHH patients. While the mechanism(s) for relapse are unclear, it seems plausible that environmental, metabolic or psychiatric stressors could contribute. The factors that Mao and colleagues identify as significantly different in cases of reversal, were not informative for identifying those cases that relapsed back to a hypogonadal state. Notably, reversal has been reported in probands harboring mutations in genes underlying CHH. [1],[3],[4],[6] Unfortunately, comprehensive genetic screening on the Chinese cohort is not available. The reversal phenomenon is fascinating for its glimpse into the plasticity of the neuroendocrine control of reproduction. Future directions will almost certainly include investigation of specific genetic signatures and novel biomarkers for predicting reversal (and relapse). Yet CHH is a rare condition and to fully elucidate the biology of reversible CHH, it will be important to harmonize definitions of what constitutes a reversal, carefully phenotype patients and chart the natural history of their CHH. In this way, this unique human disease model may offer further insights into the control of human reproduction and provide opportunities to translate discoveries into enhanced approaches to improve the care and quality of life for these patients.

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Työn päätavoite on selvittää kuinka erityisesti sähkön markkinahinnan ennustamiseen ja johdannaismarkkinoiden tietämykseen perustuva lyhyen tähtäimen sähköjohdannaisten hyödyntäminen tapahtuu teollisessa energianhallinnassa. Tätä aihetta lähestytään luomalla prosessi lyhyen tähtäimen sähköjohdannaisten hyödyntämiselle. Prosessi esitellään ja selvitetään aina lähtökohdista todelliseen kaupankäyntiin asti erillisen esimerkkitehtaan avulla.Lyhyen tähtäimen sähköjohdannaisten hyödyntäminen teollisessa energianhallinnassa perustuu pääosin tulevaisuuden odotuksiin sähkön markkinahinnan kehittymisestä sekä tehtaiden operatiiviseen tilanteeseen. Operatiiviseen tilanteeseen perustuva lyhyen tähtäimen sähköjohdannaisten kaupankäynti on pääasiassa pitkän tähtäimen suojausten sopeuttamista lyhyelle tähtäimelle sopivaksi.Hinnan ennustamisella on suuri rooli lyhyen tähtäimen sähköjohdannaisten hyödyntämisprosessissa. Työssä esitelty hinnan ennustamismalli on sopiva päivä- ja viikkotason Nord Poolin Elspot -systeemihinnan ennustamiseen. Elspot -systeemihinnan ennustamismalli on suunniteltu käytännönläheiseksi ja sen perustana ovat todelliset fysikaaliset ja mitattavat suureet. Futuurimarkkinatietämys on tarpeen lyhyen tähtäimen johdannaisia käytettäessä. Työssä tutkitaan yleisiä markkinoiden odotuksia ja futuurimarkkinoiden tietoisuuden kehittymistä koskien tulevaa vallitsevaa tilannetta. Työssä luodaan myös työkalu, mikä auttaa kaupan laatijaa muodostamaan suuntaa-antavat todennäköisyydet eri hintanäkemyksille ja paikallistamaan mahdolliset markkinoiden epätodennäköiset hintaodotukset.Kokemukset Elspot -systeemihinnan ennustamismallin soveltamisesta ovat lupaavia. Lisäksi havainnot futuurimarkkinoiden käyttäytymisestä Nord Poolissa ja muodostettu työkalu suuntaa-antavien todennäköisyyksien selvittämiseksi auttavat kaupan laatijaa päätöksenteossa. Lyhyen tähtäimen sähköjohdannaisten hyödyntäminen teollisessa energianhallinnassa on periaatteessa mahdollista esitellyn prosessin avulla, vaikka täydellinen käyttöönotto vaatisi vielä joitakin järjestelyjä. Keskittymällä tilanteisiin jotka työssä kuvatulla prosessilla ovat hoidettavissa, työssä määritellyllä menettelyllä on mahdollisuudet saavuttaa epäedullisen hintakehityksen riskin väheneminen ja parempi taloudellinen tulos teollisen energianhallinnan sähkökaupankäynnissä.