Multigene Family Evolution: Perspectives from Insect Chemoreceptors.

Understanding the birth and diversification of multigene families is a fundamental evolutionary problem. I argue for the insect chemoreceptor superfamily as an outstanding model. Although these receptors are currently the preserve of neuroscientists, putative homologous genes exist in diverse animal and plant genomes, implying an ancient origin. Moreover, functional studies suggest that they act as ligand-gated ion channels in both chemosensory and non-chemosensory processes. This family permits synergism of investigations into its structural and regulatory evolution with ecological studies of the selective pressures driving these changes. In addition, sequence divergence in these receptors can be exploited through co-evolutionary and comparative genomics analyses to help to elucidate their 3D structure and signaling mechanisms, and to reveal experimentally-accessible candidate loci to explore the genetic basis of adaptation.

Validation of and comparison between a semidistributed rainfall-runoff hydrological model (PREVAH) and a spatially distributed snow-evolution model (SnowModel) for snow cover prediction in mountain ecosystems

Snow cover is an important control in mountain environments and a shift of the snow-free period triggered by climate warming can strongly impact ecosystem dynamics. Changing snow patterns can have severe effects on alpine plant distribution and diversity. It thus becomes urgent to provide spatially explicit assessments of snow cover changes that can be incorporated into correlative or empirical species distribution models (SDMs). Here, we provide for the first time a with a lower overestimation comparison of two physically based snow distribution models (PREVAH and SnowModel) to produce snow cover maps (SCMs) at a fine spatial resolution in a mountain landscape in Austria. SCMs have been evaluated with SPOT-HRVIR images and predictions of snow water equivalent from the two models with ground measurements. Finally, SCMs of the two models have been compared under a climate warming scenario for the end of the century. The predictive performances of PREVAH and SnowModel were similar when validated with the SPOT images. However, the tendency to overestimate snow cover was slightly lower with SnowModel during the accumulation period, whereas it was lower with PREVAH during the melting period. The rate of true positives during the melting period was two times higher on average with SnowModel with a lower overestimation of snow water equivalent. Our results allow for recommending the use of SnowModel in SDMs because it better captures persisting snow patches at the end of the snow season, which is important when modelling the response of species to long-lasting snow cover and evaluating whether they might survive under climate change.

Co-evolution of Policy Sectors: Health Care and Public Health in five Countries

Cette thèse analyse la co-évolution de deux secteurs dans la politique de la santé: santé publique (public health) et soins aux malades (health care). En d'autres termes, la relation entre les dimensions curative et préventive de la politique de la santé et leur développement dans la durée. Une telle recherche est nécessaire car les problèmes de la santé sont complexes et ont besoin de solutions coordonnées. De plus, les dépenses de la santé ont augmenté sans arrt durant les dernières décennies. Un moyen de réduire une future augmentation des dépenses pourrait consister en davantage d'investissement dans des mesures préventives. En relation avec cette idée, ma recherche analyse les politiques de la santé publique et les soins aux malades de cinq pays: Allemagne, Angleterre, Australie, Etats-Unis et Suisse. En m'appuyant sur la littérature secondaire, des statistiques descriptives et des entretiens avec des experts et des politiciens, j'analyse la relation entre les deux secteurs depuis la fin du dix-neuvième siècle. En particulier, je me focalise sur la relation des deux champs sur trois niveaux: institutions, acteurs et politiques. Mes résultats montrent les similitudes et les différences d'évolution entre les cinq pays. D'un c^oté, lorsque la profession médicale est politiquement active et que le pays consiste en une fédération centralisée ou en un gouvernement unitaire, les deux secteurs sont intégrés au niveau institutionnel, ralliant les professions et groupes d'intérêt des deux secteurs la cause commune dans une activité politique. Par contre, dans tous les pays, les deux secteurs ont co-évolué vers une complémentarité malgré de la politisation des professions et la centralisation du gouvernement. Ces résultats sont intéressants pour la science politique en général car ils soulignent l'importance des professions pour le développement institutionnel et proposent un cadre pour l'analyse de la co-évolution des politiques publiques en général. -- This Ph.D. thesis analyzes the co-evolution of the health care and the public health sectors. In other words, the relation between preventive and curative health policy and its evolution over time. Such research is necessary, because current health problems are complex and might need coordinated solutions. What is more, health expenditures have increased continuously in the last decades. One way to slow down further increase in health spending could be to invest more in preventative health policies. Therefore, I am connecting individual health care and public health into a common analysis, taking Australia, Germany, Switzerland, the UK and the U.S. as examples. Based on secondary literature, descriptive statistics and interviews with experts and policymakers, I am analyzing how the two sectors' relations co-evolved between the late nineteenth and the early twenty-first century. Specifically, I am researching how health care and public health were related on the levels of institutions, actors and policies. My results show that there are differences and similarities in the co-evolution of policy sectors between these countries. On the one hand, when the medical profession was politically active and the country a centralized federation or a unitary state, there was institutional integration and common political advocacy of the sectors' interest groups and professions. On the other hand, in all countries, both sectors co-evolved towards complementarity, irrespectively of the politicization of professions and centralization of government. These findings are interesting for the political science literature at large, because they underline the importance of professions for institutional development and propose an analytical framework for analyzing the co-evolution of policy sectors in general.

A macro-ecological perspective on crassulacean acid metabolism (CAM) photosynthesis evolution in Afro-Madagascan drylands: Eulophiinae orchids as a case study.

Crassulacean acid metabolism (CAM) photosynthesis is an adaptation to water and atmospheric CO2 deficits that has been linked to diversification in dry-adapted plants. We investigated whether CAM evolution can be associated with the availability of new or alternative niches, using Eulophiinae orchids as a case study. Carbon isotope ratios, geographical and climate data, fossil records and DNA sequences were used to: assess the prevalence of CAM in Eulophiinae orchids; characterize the ecological niche of extant taxa; infer divergence times; and estimate whether CAM is associated with niche shifts. CAM evolved in four terrestrial lineages during the late Miocene/Pliocene, which have uneven diversification patterns. These lineages originated in humid habitats and colonized dry/seasonally dry environments in Africa and Madagascar. Additional key features (variegation, heterophylly) evolved in the most species-rich CAM lineages. Dry habitats were also colonized by a lineage that includes putative mycoheterotrophic taxa. These findings indicate that the switch to CAM is associated with environmental change. With its suite of adaptive traits, this group of orchids represents a unique opportunity to study the adaptations to dry environments, especially in the face of projected global aridification.

Asymmetrical nature of the Trollius-Chiastocheta interaction: insights into the evolution of nursery pollination systems

The mutualistic versus antagonistic nature of an interaction is defined by costs and benefits of each partner, which may vary depending on the environment. Contrasting with this dynamic view, several pollination interactions are considered as strictly obligate and mutualistic. Here, we focus on the interaction between Trollius europaeus and Chiastocheta flies, considered as a specialized and obligate nursery pollination system - the flies are thought to be exclusive pollinators of the plant and their larvae develop only in T.europaeus fruits. In this system, features such as the globelike flower shape are claimed to have evolved in a coevolutionary context. We examine the specificity of this pollination system and measure traits related to offspring fitness in isolated T.europaeus populations, in some of which Chiastocheta flies have gone extinct. We hypothesize that if this interaction is specific and obligate, the plant should experience dramatic drop in its relative fitness in the absence of Chiastocheta. Contrasting with this hypothesis, T.europaeus populations without flies demonstrate a similar relative fitness to those with the flies present, contradicting the putative obligatory nature of this pollination system. It also agrees with our observation that many other insects also visit and carry pollen among T.europaeus flowers. We propose that the interaction could have evolved through maximization of by-product benefits of the Chiastocheta visits, through the male flower function, and selection on floral traits by the most effective pollinator. We argue this mechanism is also central in the evolution of other nursery pollination systems.

Decoupled evolution of floral traits and climatic preferences in a clade of Neotropical Gesneriaceae.

BACKGROUND: Major factors influencing the phenotypic diversity of a lineage can be recognized by characterizing the extent and mode of trait evolution between related species. Here, we compared the evolutionary dynamics of traits associated with floral morphology and climatic preferences in a clade composed of the genera Codonanthopsis, Codonanthe and Nematanthus (Gesneriaceae). To test the mode and specific components that lead to phenotypic diversity in this group, we performed a Bayesian phylogenetic analysis of combined nuclear and plastid DNA sequences and modeled the evolution of quantitative traits related to flower shape and size and to climatic preferences. We propose an alternative approach to display graphically the complex dynamics of trait evolution along a phylogenetic tree using a wide range of evolutionary scenarios. RESULTS: Our results demonstrated heterogeneous trait evolution. Floral shapes displaced into separate regimes selected by the different pollinator types (hummingbirds versus insects), while floral size underwent a clade-specific evolution. Rates of evolution were higher for the clade that is hummingbird pollinated and experienced flower resupination, compared with species pollinated by bees, suggesting a relevant role of plant-pollinator interactions in lowland rainforest. The evolution of temperature preferences is best explained by a model with distinct selective regimes between the Brazilian Atlantic Forest and the other biomes, whereas differentiation along the precipitation axis was characterized by higher rates, compared with temperature, and no regime or clade-specific patterns. CONCLUSIONS: Our study shows different selective regimes and clade-specific patterns in the evolution of morphological and climatic components during the diversification of Neotropical species. Our new graphical visualization tool allows the representation of trait trajectories under parameter-rich models, thus contributing to a better understanding of complex evolutionary dynamics.