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.

The Making of Experimental Economics: Witness Seminar on the Emergence of a Field

This book is the transcript of a witness seminar on the history of experimental economics, in which eleven high-profile experimental economists participated, including Nobel Laureates Vernon Smith, Reinhard Selten and Alvin Roth. The witness seminar was constructed along four different topics: skills, community, laboratory, and funding. The transcript is preceded by an introduction explaining the method of the witness seminar and its specific set-up and resuming its results. The participants' contribution and their lively discussion provide a wealth of insights into the emergence of experimental economics as a field of research.

Speed limit laws in America: economics, politics and geography

The regulation of speed limits in the US had been centralized at the federal level since 1974, until decisions were devolved to the states in 1995. However, the centralization debate has reemerged in recent years. Here, we conduct the first econometric analysis of the determinants of speed limit laws. By using economic, geographic and political variables, our results suggest that geography -which affects private mobility needs and preferences- is the main factor influencing speed limit laws. We also highlight the role played by political ideology, with Republican constituencies being associated with higher speed limits. Furthermore, we identify the presence of regional and time dependence effects. By contrast, poor road safety outcomes do not impede the enactment of high speed limits. Overall, we present the first evidence of the role played by geographical, ideological and regional characteristics, which provide us with a better understanding of the formulation of speed limit policies.

The Association of H1N1 Pandemic Influenza with Congenital Anomaly Prevalence in Europe: An Ecological Time Series Study.

BACKGROUND: In the context of the European Surveillance of Congenital Anomalies (EUROCAT) surveillance response to the 2009 influenza pandemic, we sought to establish whether there was a detectable increase of congenital anomaly prevalence among pregnancies exposed to influenza seasons in general, and whether any increase was greater during the 2009 pandemic than during other seasons. METHODS: We performed an ecologic time series analysis based on 26,967 pregnancies with nonchromosomal congenital anomaly conceived from January 2007 to March 2011, reported by 15 EUROCAT registries. Analysis was performed for EUROCAT-defined anomaly subgroups, divided by whether there was a prior hypothesis of association with influenza. Influenza season exposure was based on World Health Organization data. Prevalence rate ratios were calculated comparing pregnancies exposed to influenza season during the congenital anomaly-specific critical period for embryo-fetal development to nonexposed pregnancies. RESULTS: There was no evidence for an increased overall prevalence of congenital anomalies among pregnancies exposed to influenza season. We detected an increased prevalence of ventricular septal defect and tricuspid atresia and stenosis during pandemic influenza season 2009, but not during 2007-2011 influenza seasons. For congenital anomalies, where there was no prior hypothesis, the prevalence of tetralogy of Fallot was strongly reduced during influenza seasons. CONCLUSIONS: Our data do not suggest an overall association of pandemic or seasonal influenza with congenital anomaly prevalence. One interpretation is that apparent influenza effects found in previous individual-based studies were confounded by or interacting with other risk factors. The associations of heart anomalies with pandemic influenza could be strain specific.

Observation and Observing in Economics

Two themes are generative for revealing and understanding the history of observation in economics. First, we argue for the importance of noting that observation is an activity as well as a result, and second that observation is no more identical with quantification than observing is with measuring. These two themes enable us to discuss different historical dimensions of the ways in which economists have observed their economies and so enlarge our understanding of their observational practices. These problematics especially help in delineating the intricate, multilayered, and active interactions between the observer and the observed that take place in all social science observation, and from which our pictures of the economic world emerge.

Timing History: The Introduction of Graphical Analysis in 19th Century British Economics

The introduction of time-series graphs into British economics in the 19th century depended on the « timing » of history. This involved reconceptualizing history into events which were both comparable and measurable and standardized by time unit. Yet classical economists in Britain in the early 19th century viewed history as a set of heterogenous and complex events and statistical tables as giving unrelated facts. Both these attitudes had to be broken down before time-series graphs could be brought into use for revealing regularities in economic events by the century's end.

Essays on the Economics of Conflict and Migration

Les conflits civils sont des événements dramatiques qui poussent les individus hors de leurs pays d'origine. Mais si l'émigration était elle-même une force pacificatrice? Dans les deux premiers chapitres, je me suis intéressée à l'impact de l'émigration sur l'incidence des conflits civils dans les pays d'origine. Tout d'abord, je construis un modèle théorique d'équilibre général, dans lequel le niveau de conflit d'équilibre est déterminé par la ratio de combattants dans l'économie. Dans ce modèle, l'émigration décourage les conflits en réduisant les gains d'une rébellion, tout en augmentant le coût d'opportunité des combats. La principale prédiction du modèle est que le conflit diminue avec le niveau du salaire étranger net des coûts de migration. Dans le deuxième chapitre, je teste cette prédiction empiriquement. En utilisant une variable instrumentale, je démontre que l'émigration vers les pays développés diminue l'incidence de guerres civiles dans les pays d'origine. Ces résultats prouvent qu'en ouvrant leurs frontières, les pays d'accueil pourraient contribuer à sauver des vies, aussi bien celles des migrants que celles des habitants restés dans leur pays. De plus, les conflits civils tendent à détruire des sociétés en traumatisant les personnes touchées, augmentant ainsi le risque des conflits futurs. Afin de mieux comprendre ce cercle vicieux et de pouvoir y remédier, le troisième chapitre détermine si les enfants ayant vécu la guerre ont une tendance à être plus violent que des co-nationaux nés après la guerre. L'analyse se concentre sur les demandeurs d'asile en Suisse : Cette population est intéressante puisque l'allocation des demandeurs d'asile entre cantons est aléatoire, ce qui prévient le choix d'un canton avec un taux de criminalité plus élevé. Les résultats démontrent un effet de traumatisme causé par la guerre augmentant ainsi le risque de criminalité dans la vie adulte. Cependant, l'analyse de politiques publiques montre que la mise en place de politiques judicieuses permet d'éviter les conséquences de l'exposition à la guerre. En particulier, en offrant aux nouveaux arrivants l'accès au marché de travail ainsi que des perspectives à long-terme, la Suisse peut éliminer complètement l'effet du traumatisme sur la criminalité.

Vulnerability of stream biota to climate change in mediterranean climate regions: a synthesis of ecological responses and conservation challenges

Freshwater species worldwide are experiencing dramatic declines partly attributable to ongoing climate change. It is expected that the future effects of climate change could be particularly severe in mediterranean climate (med-) regions, which host many endemic species already under great stress from the high level of human development. In this article, we review the climate and climate-induced changes in streams of med-regions and the responses of stream biota, focusing on both observed and anticipated ecological responses. We also discuss current knowledge gaps and conservation challenges. Expected climate alterations have already been observed in the last decades, and include: increased annual average air temperatures; decreased annual average precipitation; hydrologic alterations; and an increase in frequency, intensity and duration of extreme events, such as floods, droughts and fires. Recent observations, which are concordant with forecasts built, show stream biota of med-regions when facing climate changes tend to be displaced towards higher elevations and upper latitudes, communities tend to change their composition and homogenize, while some life-history traits seem to provide biota with resilience and resistance to adapt to the new conditions (as being short-lived, small, and resistant to low streamflow and desiccation). Nevertheless, such responses may be insufficient to cope with current and future environmental changes. Accurate forecasts of biotic changes and possible adaptations are difficult to obtain in med-regions mainly because of the difficulty of distinguishing disturbances due to natural variability from the effects of climate change, particularly regarding hydrology. Long-term studies are needed to disentangle such variability and improve knowledge regarding the ecological responses and the detection of early warning signals to climate change. Investments should focus on taxa beyond fish and macroinvertebrates, and in covering the less studied regions of Chile and South Africa. Scientists, policy makers and water managers must be involved in the climate change dialogue because the freshwater conservation concerns are huge.

Ecological change predicts population dynamics and genetic diversity over 120 000 years.

While ecological effects on short-term population dynamics are well understood, their effects over millennia are difficult to demonstrate and convincing evidence is scant. Using coalescent methods, we analysed past population dynamics of three lizard species (Psammodromus hispanicus, P. edwardsianus, P. occidentalis) and linked the results with climate change data covering the same temporal horizon (120 000 years). An increase in population size over time was observed in two species, and in P. occidentalis, no change was observed. Temporal changes in temperature seasonality and the maximum temperature of the warmest month were congruent with changes in population dynamics observed for the three species and both variables affected population density, either directly or indirectly (via a life-history trait). These results constitute the first solid link between ecological change and long-term population dynamics. The results moreover suggest that ecological change leaves genetic signatures that can be retrospectively traced, providing evidence that ecological change is a crucial driver of genetic diversity and speciation.