Genetic diversity for RAPD markers between cultivated and wild accessions of Coffea arabica

Des marqueurs RAPD (Random Amplified Polymorphic DNA) ont été utilisés avec succès pour analyser la diversité génétique parmi des accessions sauvages et cultivées de #Coffea arabica. La base génétique étroite des cultivars est confirmée. En revanche, une relative large diversité est observée dans le matériel sauvage illustrant l'intérêt des prospections. Des résultats suggèrent une différenciation génétique Est-Ouest en Ethiopie qui constitue le centre primaire de diversification de #C. arabica. L'important effet d'hétérosis observé chez des hybrides intergroupes pourrait être lié à cette différenciation génétique. La méthode RAPD apparaît performante pour l'étude de la variabilité génétique et la classification du germplasm de #C. arabica$. (Résumé d'auteur

Questionnaire-based assessment of wild boar/domestic pig interactions and implications for disease risk management in Corsica

Wild boars and domestic pigs belong to the same species (Sus scrofa). When sympatric populations of wild boars, feral pigs, and domestic pigs share the same environment, interactions between domestic and wild suids (IDWS) are suspected to facilitate the spread and maintenance of several pig pathogens which can impact on public health and pig production. However, information on the nature and factors facilitating those IDWS are rarely described in the literature. In order to understand the occurrence, nature, and the factors facilitating IDWS, a total of 85 semi-structured interviews were implemented face to face among 25 strict farmers, 20 strict hunters, and 40 hunting farmers in the main traditional pig-farming regions of Corsica, where IDWS are suspected to be common and widespread. Different forms of IDWS were described: those linked with sexual attraction of wild boars by domestic sows (including sexual interactions and fights between wild and domestic boars) were most frequently reported (by 61 and 44% of the respondents, respectively) in the autumn months and early winter. Foraging around common food or water was equally frequent (reported by 60% of the respondents) but spread all along the year except in winter. Spatially, IDWS were more frequent in higher altitude pastures were pig herds remain unattended during summer and autumn months with limited human presence. Abandonment of carcasses and carcass offal in the forest were equally frequent and efficient form of IDWS reported by 70% of the respondents. Certain traditional practices already implemented by hunters and farmers had the potential to mitigate IDWS in the local context. This study provided quantitative evidence of the nature of different IDWS in the context of extensive commercial outdoor pig farming in Corsica and identified their spatial and temporal trends. The identification of those trends is useful to target suitable times and locations to develop further ecological investigations of IDWS at a finer scale in order to better understand diseases transmission patterns between populations and promote adapted management strategies

Flocking as a Synchronization Phenomenon with Logistic Agents

International audienceIn this paper, we intend to show that the flocking phenomenon observed in many animal species behaviors, may be modeled as a synchronization process occurring within entity states. Although flocking has been widely studied and simulated in Swarm Intelligence, few works mention synchronization as a key aspect of the problem and model it properly. This paper proposes a modeling in terms of a reactive multi-agent system composed of interacting logistic agents moving in an environment. This specific MAS called Logistic MAS (LMAS) takes actually inspiration from the coupled map lattice field, which provides also many tools to analyse convergence and stability of the system. We develop our approach in both theoretical and applied way to demonstrate its relevance

Les caféiers en Afrique : diversité génétique et amélioration des plantes

Des collectes de caféiers sauvages, dans la zone tropicale humide africaine, ont permis de constituer une collection vivante des différentes espèces de #Coffea. L'étude de leur diversité génétique a été entreprise en utilisant des descripteurs botaniques et enzymatiques, ainsi que des tests d'hybridation interspécifique. On constate que les espèces de caféiers sont inégalement réparties sur l'ensemble de l'aire de la forêt tropicale humide. A l'intérieur des espèces, une structure génétique peut être mise en évidence, différente d'une espèce à l'autre. En combinant ces résultats aux observations des hybridations interspécifiques, il est proposé une organisation du genre #Coffea en trois sections. D'une façon générale, une réflexion est menée sur la notion d'espèce et l'évolution de ces espèces, en liaison avec les modifications du paléoenvironnement. Les conséquences pratiques de ces études pour l'amélioration des caféiers sont les suivantes : 1. L'introgression des formes cultivées est tentée avec les espèces sauvages possédant des caractères particuliers d'intérêt agronomique ; 2. L'espèce #C. canephora$ est constituée de deux groupes et les hybrides F1 entre les deux groupes sont très productifs ; un schéma de Sélection Récurrente Réciproque avec création d'hybrides F1 est donc appliqué. (Résumé d'auteur

A Nonlinear Multi-agent System designed for Swarm Intelligence : the Logistic MAS

International audienceAnt algorithms and flocking algorithms are the two main programming paradigms in swarm intelligence. They are built on stochastic models, widely used in optimization problems. However, though this modeling leads to high-performance algorithms, some mechanisms, like the symmetry break in ant decision, are still not well understood at the local ant level. Moreover, there is currently no modeling approach which joins the two paradigms. This paper proposes an entirely novel approach to the mathematical foundations of swarm algorithms: contrary to the current stochastic approaches, we show that an alternative deterministic model exists, which has its origin in deterministic chaos theory. We establish a reactive multi-agent system, based on logistic nonlinear decision maps, and designed according to the influence-reaction scheme. The rewriting of the decision functions leads to a new way of understanding the swarm phenomena in terms of state synchronization, and enables the analysis of their convergence behavior through bifurcation diagrams. We apply our approach on two concrete examples of each algorithm class, in order to demonstrate its general applicability

Deterministic Nonlinear Modeling of Ant Algorithm with Logistic Multi-Agent System

International audienceAnt algorithms are one of the main programming paradigms in swarm intelligence. They are built on stochastic decision functions, which can also be found in other types of bio-inspired algorithms with the same mathematical form. However, though this modeling leads to high-performance algorithms, some phenomena, like symmetry break, are still not well understood or modeled at the ant level. This paper proposes an original analysis of the problem : we establish a reactive multi-agent system based on logistic nonlinear decision maps, and designed according to the influence-reaction scheme. Our proposition is an entirely novel approach to the mathematical foundations of ant algorithms : contrary to the current stochastic approaches, we show that an alternative deterministic model exists, which has its origin in deterministic chaos theory. The rewriting of the decision functions leads to a new way of understanding and visualizing the convergence behavior of ant algorithms. We apply our approach on a concrete example, namely the binary bridge problem

Study of Self-adaptation Mechanisms in a Swarm of Logistic Agents

International audienceWe are interested in addressing the problem of coordinating a large number of simple agents in order to achieve a given task. Stated in this way, the question leads naturally to the Swarm Intelligence field. In this paper we use a new type of model, directly inspired by Kaneko's coupled map gas model which we have adapted to the multi-agent system paradigm, so as to tackle this generic objective. This model is called a logistic multi-agent system (LMAS): it is composed of reactive situated agents whose individual behavior is governed by a logistic map or more generally a quadratic map. The collective behavior results from couplings between agents and local controls on agents adjusted by local environmental conditions. This way of modelling reveals to enable a wide range of pattern formations and various forms of adaptation to the environment. This paper focuses on the way to design the constitutive mechanisms of LMAS –particularly the perception and action processes– and on the way a self-adaptation process may result from these mechanisms. This study is illustrated with experiments on the predators-prey pursuit problem, in which a set of agents (predators) has to encircle a moving prey. We show that coupling the internal states of agents leads to amplifying the predator aggregation around the prey, whereas altering the internal control variable in each agent through environment perceptions modifies the predator sensitivity to the prey. We finally complete this study by relating the concept of adaptation with concepts of the dynamical system theory: a qualitative dynamical analysis of the capturing process leads to view the prey as a dynamical fixed point of the system