Physiological Correlates of Urbanization in a Desert Songbird

Rapid worldwide urbanization is creating novel environments to which animals must adapt, a topic of growing interest for biologists. Studies of how organisms are affected by cities historically centered on large-scale censusing of populations, but recent investigations have considered finer-scaled, urban-rural differences among individuals and species in their behavior, morphology, and physiology, specifically as they relate to urban stress. A number of factors (e.g., corticosterone (CORT)-related stress response) may contribute to the degree of stress experienced by animals living under urban versus natural conditions, but several physiological variables have yet to be considered together in a large-scale assessment. Here, in a widespread species of desert passerine (the house finch, Haemorhous mexicanus), we quantified variation in plasma oxidative stress, plasma concentrations of vitamins and carotenoids, and body-mass of males in three successive seasons (winter, spring, and late summer/early fall) along an urban-rural gradient in Phoenix, Arizona, USA. We found that degree of urbanization was: (1) negatively related to circulating vitamin A concentrations in winter, (2) positively correlated with body-mass during spring, and (3) negatively associated with plasma concentrations of two carotenoids: zeaxanthin (during breeding) and 3-hydroxy-echinenone (3HE) (during molting). The striking link between 3HE levels and urbanization is consistent with previous research showing that urban songbirds have lower carotenoid levels and faded plumage; our finding is the first to implicate specific effects on a metabolically derived carotenoid for coloration. The fact that we observed only season-specific links between urbanization and indicators of quality in finches suggests that (at least for these metrics) there are no strong, lasting urban pressures imposed on finch physiology over the year. Interestingly, we found that a metric of plasma oxidative stress (lipid peroxidation) was positively correlated with levels of two carotenoids (lutein during breeding and 3HE during molting), which is consistent with a prior study of ours showing that finches with redder plumage deposit higher levels of CORT in their feathers; taken together, our studies suggest complex associations between carotenoids and stres

Forces fluctuantes générées par un écoulement diphasique interne : mécanisme et modélisation.

RÉSUMÉ D’une manière générale, les écoulements diphasiques se divisent en trois sous catégories de mélanges diphasiques. Ces derniers peuvent être constitués de deux liquides non-miscibles, d’un même fluide dans deux états différents, ou de deux fluides différents dont l’un est sous forme liquide et l’autre sous forme gazeuse. Lors de l’écoulement d’un tel mélange, la variation de la masse volumique qui traverse un volume donné peut générer d’importantes forces dans les éléments de tuyauterie. Ces phénomènes se produisent particulièrement dans l’industrie nucléaire, utilisant des réacteurs à eau bouillante (BWR) et à eau lourde pressurisée (PHWR), ou dans l’industrie liée à l’extraction et à la transformation du pétrole. La majorité des travaux précédents ont été réalisés avec des mélanges air-eau. Certains d’entre eux ont utilisé des additifs dans l’eau afin de faire varier les paramètres physiques de l’écoulement, tels que la tension de surface du mélange, la masse volumique et la viscosité du liquide. Peu de tests ont été réalisés avec un mélange eau-vapeur, principalement à cause des coûts et de la complexité de mise en oeuvre d’un tel mélange. Ces différentes études ont démontré que les forces générées par un écoulement diphasique sont quasi-périodiques à basses fréquences. Ainsi, si elles ne sont pas prises en compte dans le dimensionnement des ensembles de tuyauteries, ces forces peuvent générer d’importantes vibrations. Ces dernières provoquent des dommages à causes de l’usure prématurée des composants, pouvant aller jusqu’à leur rupture. Dépendamment du titre volumique, de la vitesse de chaque phase et des propriétés physiques du mélange, les écoulements adoptent différentes structures. Afin de prédire précisément les forces générées par celles-ci, il est nécessaire d’identifier clairement les différents types d’écoulements en fonction des paramètres qui les caractérisent. Pour ce faire, différents auteurs ont développé des modèles de transitions afin de produire des cartes de configurations d’écoulement diphasique vertical et horizontal. Néanmoins, pour une même transition, il existe parfois plusieurs modèles qui se basent sur des mécanismes différents. Par conséquent, il est nécessaire de regrouper les transitions qui correspondent le mieux à celles identifiées dans les conditions étudiés. Ceci va nous permettre de proposer une carte plus précise, afin de prédire la nature des forces dues aux écoulements diphasiques.----------ABSTRACT Two-phase flows include three sub-categories of two-phase mixtures. They may consist of two immiscible liquids, of a single fluid in two different states or of two different fluids, the first in liquid form and the second in gaseous form. The variation in density of two-phase flow passing through a given volume can generate significant forces in piping elements. This phenomenon usually occurs in industries related to the extraction and processing of petroleum and in the nuclear industry, ie: boiling water reactors (BWR) and pressurized heavy water reactors (PHWR). Most previous experiments were conducted with air-water mixtures. Some of the experiments used additives in water to vary the physical parameters of the flow, e.g.; surface tension, fluids density or liquid viscosity. Due to the more difficult implementation of the steam-water mixture, only a handful of works has been conducted with this type of mixture. All of the studies have shown that two-phase flows induce quasi-periodic forces, at low frequency. So if they are not taken into account in the piping elements design, two-phase flow induced forces can generate strong vibrations. The vibrations cause damage due to the premature wear of components, up to failures. Depending on the void fraction, superficial velocities, and physical properties of the mixture, two-phase flows consist of different structures. To predict more precisely the forces generated by the different flows, it is necessary to clearly identify the different flow patterns, depending on flow parameters. Various models had been developed to compute vertical and horizontal two-phase flow pattern transition boundaries. However, for the same transition, several models exist, based on apparently different mechanisms. It is therefore necessary to select transition boundaries which best fit over the range of two-phase flow conditions studied. A proposed map makes it possible to predict more precisely the nature of forces depending on the two-phase flow pattern. The main objective of the present work is to study the fluctuating forces in a vertical U-tube and horizontal elbow. This study establishes the relationship between the different types of flows and the frequency behavior of the induced forces

Nutritional status does not explain the increase of carotenoid-based coloration associated with age in Great Tits Parus major

In many bird species, yearling individuals are less colorful than older ones. However, the causal factors behind this difference of color are for the moment unknown. Here, we used ptilochronology in Great Tits Parus major to assess how nutritional conditions experienced by the same birds as yearling and adult are associated with this increase of coloration. Nutritional status was not different between yearling and adult individuals, suggesting that the increase in coloration with age is not due to an increase in foraging efficiency with age. Instead, our study implicates other behavioral and/or ecophysiological factors that drive yearling/adult differences in carotenoid ornamentation

Parasites, mate attractiveness and female feather corticosterone levels in a socially monogamous bird

Stress is ubiquitous in the life of animals and a key determinant of their well-being and fitness. By quantifying levels of feather corticosterone in growing feathers (CORTf), we measured integrated stress responses in a monogamous game bird, the red grouse Lagopus lagopus scoticus. We investigated the effects of parasites and social mate choice on female CORTf levels during pairing, and tested the hypothesis that females with more parasites and paired with less attractive males have higher CORTf. We experimentally reduced nematode parasite abundance during pairing in females and investigated the effect of treatment on CORTf, while also considering the social mate’s phenotype (male comb size, as a proxy of sexual attractiveness). The treatment was effective at contrasting parasite loads between control and dosed females, but had no apparent effect on CORTf. In experimental females, reinfection rate after a month positively correlated with CORTf. We found no evidence of assortative mating based on size, condition or ornament size, but females paired with more attractive males (displaying bigger combs) had lower CORTf during pairing. Females for which parasite load was reduced had lower CORTf than control females at all levels of male attractiveness. Social mate choice therefore appears to be an important determinant of female integrated stress responses, which may in turn modulate reinfection rate and parasitism risk. An influence of male attractiveness on female stress may be part of an adaptive response allowing females to adjust reproductive investment to their achieved social mate choice

Etude de paliers hydrodynamiques présentant de fortes discontinuités géométriques

Lors de diverses opérations de maintenance du parc EDF, de nouvelles problématiques ont été mises en lumière. L'une d'entre elles est la dégradation des rotors et des organes de supportage du groupe turbo-alternateur. Ceci se traduit par la présence de rayures au niveau des paliers hydrodynamiques synonymes de fortes discontinuités dans le film d'huile. L'exploitant doit être en mesure de fournir un diagnostic rapide sur l'influence de celles-ci. Pour donner une réponse fiable et rapide, EDF dispose d'un logiciel qui présente, dans certains configurations comportant des discontinuités importantes, quelques faiblesses comme la non conservation du débit lorsqu'il y a rupture puis reformation du film lubrifiant ou encore des problèmes de robustesse et de rapidité des calculs. C'est dans ce contexte que s'inscrivent ces travaux de thèse. Les différents objectifs sont une meilleure prise en compte de la physique pour les différents phénomènes étudiés, améliorer les performances et la robustesse des calculs au moyen de méthodes de résolution numériques adaptées à cette problématique particulière

Differences in mutational processes and intratumour heterogeneity between organs: the local selective filter hypothesis.

International audienceExtensive diversity (genetic, cytogenetic, epigenetic and phenotypic) exists within and between tumors, but reasons behind these variations, as well as their consistent hierarchical pattern between organs, are poorly understood at the moment. We argue that these phenomena are, at least partially, explanable by the evolutionary ecology of organs’ theory, in the same way that environmental adversity shapes mutation rates and level of polymophism in organisms. Organs in organisms can be considered as specialized ecosystems that are, for ecological and evolutionary reasons, more or less efficient at supressing tumours. When a malignancy does arise in an organ applying strong selection pressure on tumours, its constituent cells are expected to display a large range of possible surviving strategies, from hyper mutator phenotypes relying on bet-hedging to persist (high mutation rates and high diversity), to few poorly variable variants that become invisible to natural defences. In contrast, when tumour suppression is weaker, selective pressure favouring extreme surviving strategies is relaxed, and tumours are moderately variable as a result. We provide a comprehensive overview of this hypothesis

The ecology and evolution of wildlife cancers: Applications for management and conservation

Evolutionary Applications published by John Wiley & Sons Ltd Ecological and evolutionary concepts have been widely adopted to understand host–pathogen dynamics, and more recently, integrated into wildlife disease management. Cancer is a ubiquitous disease that affects most metazoan species; however, the role of oncogenic phenomena in eco-evolutionary processes and its implications for wildlife management and conservation remains undeveloped. Despite the pervasive nature of cancer across taxa, our ability to detect its occurrence, progression and prevalence in wildlife populations is constrained due to logistic and diagnostic limitations, which suggests that most cancers in the wild are unreported and understudied. Nevertheless, an increasing number of virus-associated and directly transmissible cancers in terrestrial and aquatic environments have been detected. Furthermore, anthropogenic activities and sudden environmental changes are increasingly associated with cancer incidence in wildlife. This highlights the need to upscale surveillance efforts, collection of critical data and developing novel approaches for studying the emergence and evolution of cancers in the wild. Here, we discuss the relevance of malignant cells as important agents of selection and offer a holistic framework to understand the interplay of ecological, epidemiological and evolutionary dynamics of cancer in wildlife. We use a directly transmissible cancer (devil facial tumour disease) as a model system to reveal the potential evolutionary dynamics and broader ecological effects of cancer epidemics in wildlife. We provide further examples of tumour–host interactions and trade-offs that may lead to changes in life histories, and epidemiological and population dynamics. Within this framework, we explore immunological strategies at the individual level as well as transgenerational adaptations at the population level. Then, we highlight the need to integrate multiple disciplines to undertake comparative cancer research at the human–domestic–wildlife interface and their environments. Finally, we suggest strategies for screening cancer incidence in wildlife and discuss how to integrate ecological and evolutionary concepts in the management of current and future cancer epizootics

Darwin, the devil, and the management of transmissible cancers

Modern conservation science frequently relies on genetic tools to manage imperiled populations threatened by processes such as habitat fragmentation and infectious diseases. Translocation of individuals to restore genetic diversity (genetic rescue) is increasingly used to manage vulnerable populations, but it can swamp local adaptations and lead to outbreeding depression. Thus, genetic management is context dependent and needs evaluation across multiple generations . Genomic studies can help evaluate the extent to which populations are locally adapted to assess the costs and benefits of translocations. Predicting the long‐term fitness effects of genetic interventions and their evolutionary consequences is a vital step in managing dwindling populations threatened by emerging infectious diseases

Transmissible cancer and the evolution of sex

The origin and subsequent maintenance of sex and recombination are among the most elusive and controversial problems in evolutionary biology. Here, we propose a novel hypothesis, suggesting that sexual reproduction not only evolved to reduce the negative effects of the accumulation of deleterious mutations and processes associated with pathogen and/or parasite resistance but also to prevent invasion by transmissible selfish neoplastic cheater cells, henceforth referred to as transmissible cancer cells. Sexual reproduction permits systematic change of the multicellular organism\u27s genotype and hence an enhanced detection of transmissible cancer cells by immune system. Given the omnipresence of oncogenic processes in multicellular organisms, together with the fact that transmissible cancer cells can have dramatic effects on their host fitness, our scenario suggests that the benefits of sex and concomitant recombination will be large and permanent, explaining why sexual reproduction is, despite its costs, the dominant mode of reproduction among eukaryotes

Ecological and evolutionary consequences of anticancer adaptations

Cellular cheating leading to cancers exists in all branches of multicellular life, favoring the evolution of adaptations to avoid or suppress malignant progression, and/or to alleviate its fitness consequences. Ecologists have until recently largely neglected the importance of cancer cells for animal ecology, presumably because they did not consider either the potential ecological or evolutionary consequences of anticancer adaptations. Here, we review the diverse ways in which the evolution of anticancer adaptations has significantly constrained several aspects of the evolutionary ecology of multicellular organisms at the cell, individual, population, species, and ecosystem levels and suggest some avenues for future research