Ecological Opportunity In Adaptive Radiation Of Galapagos Endemic Land Snails

The classic evolutionary hypothesis of ecological opportunity proposes that both heterogeneity of resources and freedom from enemies promote phenotypic divergence as a response to increased niche availability. Although phenotypic divergence and speciation have often been inferred to be the primary consequences of the release from competition or predation that accompanies a shift to a new adaptive zone, increased phenotypic variation within species is expected to represent the first stage resulting from such a shift. Using measures of intraspecific morphological variation of 30 species of Galapagos endemic land snails in a phylogenetically controlled framework, we show that the number of local congeners and the number of local plant species are associated with lower and higher intraspecific phenotypic variation, respectively. In this clade, ecological opportunity thus explicitly links the role of competition from congeners and the heterogeneity of resources to the extent of intraspecific phenotypic divergence as adaptive radiation proceeds.Integrative Biolog

Analyse de fiabilité en modélisation hydrologique: Concepts et applications au modèle pluies-débits GR3

Pour étudier les incertitudes d'un modèle hydrologique, on peut employer l'analyse de fiabilité, méthode couramment utilisée dans le domaine de la résistance des structures et du génie hydraulique. Cet outil peut être transposé dans le domaine hydrologique pour juger de la qualité d'un modèle. Un modèle hydrologique sera fiable si, sur une série de données test, l'ajustement obtenu avec un jeu de paramètres recommandé pour un fonctionnement passe-partout est, selon toute probabilité, d'une qualité proche de l'ajustement idéal correspondant au calage du jeu de paramètres sur l'échantillon test. Ce papier montre comment adapter chacun des concepts de l'analyse de fiabilité en hydrologie et détaille la technique des deux premiers moments afin de calculer explicitement la fiabilité d'un modèle-pluie débit en réalisant un développement limité au voisinage du point de fonctionnement du modèle.Cette approche par analyse de fiabilité est appliquée au modèle GR3 à titre d'illustration pour juger de la pertinence de ce modèle pluie-débit conceptuel à trois paramètres en situation de prédiction des crues à court pas de temps sur un bassin versant situé dans la région de la Côte d'Azur en France . Les résultats numériques obtenus montrent le caractère opérationnel de cette approche très simple. D'autre part, ces calculs de fiabilité mettent en évidence la réponse du modèle à chacun des paramètres. Enfin en mesurant la performance de représentativité d'un modèle selon plusieurs dimensions telles l'erreur quadratique d'ajustement, l'erreur sur le volume de crue prévue ou l'importance de l'écart de pointe de crue, l'analyse de fiabilité peut être naturellement étendue vers une approche multicritère en considérant des probabilités conjointes de satisfaction du modèle sur chacun de ces critères.Reliability analysis is a method for evaluating the risk of failure of a system and this concept is widely used in structure design. The theory can be conveniently transposed to the field of water sciences so as to evaluate the quality of hydrologic models. Hydrological reliability of a model is defined as the probability that there will not be significant different performances between this model, with parameters assessed on the basis of a large sample including various hydrological conditions, and the same model running with ad hoc parameters estimated from the test sample. Consequently a tolerance threshold has to be introduced in reliability analysis for hydrological models. A number of conceptual differences between validation and reliability analysis are reviewed and categorized.This paper shows how to adapt the concepts of reliability to hydrology and gives details of the first two moment technique that can be implemented to compute the reliability of a rainfall runoff model. This technique is based on a Taylor series developed in the neighborhood of the model working point. This simplification allows for an explicit expression of the expectation and the variance of the hydrological model performance as functions of the marginal sensitivity of the criterion and the parameter uncertainties. A Student ratio can be easily computed to evaluate the quality of a hydrological model from a reliability-based point of view.The GR3 model is used to illustrate this technique. A reliability analysis of this three parameter conceptual rainfall-runoff model gives new insight into the performance of the model for short-term flood prediction in the Réal Collobrier river basin located in the French Côte d'Azur. Numerical results show that the reliability analysis approach is very simple and of practical interest. For 16 of the 18 samples used for validation, the GR3 rainfall runoff model proved to be reliable on the basis of the three criteria used in this paper to evaluate the quality of a hydrological model (general quadratic deviation loss of runoffs, flood volume error and flood peak error). Using reliability analysis, contributions of each parameter to the variance of the performance function can be conveniently identified. For the GR3 model and the Réal Collobrier case study, the impacts of each parameter on the model efficiency are as follows:- The contribution of a parameter varies from one criterion to another. This indicates that a parameter originally designed to play a specific role in the modeling of the rainfall runoff transformation process does contribute to the criterion that best describes this function, which confirms the conceptual "good sense" of GR3. - For each criterion, the cross contributions are very low: the GR3 model satisfies the principle of parsimony and each parameter adds something different to the general behavior of GR3. In this case study, the GR3 model exhibits a good balance between complexity and quality for hydrological models.Finally, reliability analysis can provide a multicriteria point of view of the model qualities by changing the various indices of performance. Extension of reliability analysis towards engineering risk would include the estimation of joint probability distributions for these multiple criteria of interest

Sequential ranking procedures

Sequential ranking procedures, stochastic processes, and statistical analysi

The continued traction of Kennedy assassination theories shows that our predispositions towards believing in conspiracies are as strong as ever

Friday marks the 50th anniversary of the assassination of President John F. Kennedy in Dallas, Texas. While nearly five decades have passed since the event, conspiracy theories still abound as to who was behind the killing. Joseph Uscinski and Joseph Parent argue that Kennedy assassination theories have been among the most durable because of the enormous coverage and discussions that have surrounded them since 1963, and the deference that they receive in the mainstream media. They write that as long as people are socialized to be more predisposed to see conspiracies, conspiratorial beliefs will remain with us

USE OF INHALANT ANESTHETICS IN THREE SNAKE SPECIES

Different snake species respond differently to various anesthetic agents. Hence, an anesthetic procedure developed for one species cannot necessarily be safely transferred to another species. The goal of this paper is to summarize our experience using inhalant anesthetics on three snake species, including both procedures that were successful and those we found to be less satisfactory. We found isoflurane delivered with a precision vaporizer to be the best agent to anesthetize black rat snakes (Elaphe o. obsoleta). Sex and mass did not seem to affect induction times in black rat snakes, but larger female rat snakes recovered faster from anesthesia than smaller females. Halothane delivered in the open method provided consistent anesthesia in northern water snakes (Nerodia s. sipedon), although it caused some mortality and should not be used on debilitated patients. Halothane delivered with a precision vaporizer may be used to anesthetize eastern massasauga rattlesnakes (Sistrurus c. catenatus). However, care must be taken to prevent mortality resulting from anesthetic overdose. Sex and mass had no effect on induction and recovery times in the rattlesnakes, but stressed animals require longer induction and recovery times