22 research outputs found
Genetic diversity and networks of exchange: A combined approach to assess intra-breed diversity
Background: Cryopreservation of three endangered Belgian sheep breeds required to characterize their intra-breed genetic diversity. It is assumed that the genetic structure of a livestock breed depends mostly on gene flow due to exchanges between herds. To quantify this relation, molecular data and analyses of the exchanges were combined for three endangered Belgian breeds. Methods: For each breed, between 91 and 225 sheep were genotyped with 19 microsatellites. Genetic differentiations between breeds and among herds within a breed were evaluated and the genetic structure of the breeds was described using Bayesian clustering (Structure). Exchanges of animals between 20, 46 and 95 herds according to breed were identified via semi-directed interviews and were analyzed using the concepts of the network theory to calculate average degrees and shortest path lengths between herds. Correlation between the Reynolds genetic distances and the shortest path lengths between each pair of herds was assessed by a Mantel test approach. Results: Genetic differentiation between breeds was high (0.16). Overall Fst values among herds were high in each breed (0.17, 0.11 and 0.10). Use of the Bayesian approach made it possible to identify genetic groups of herds within a breed. Significant correlations between the shortest path lengths and the Reynolds genetic distances were found in each breed (0.87, 0.33 and 0.41), which demonstrate the influence of exchanges between herds on the genetic diversity. Correlation differences between breeds could be explained by differences in the average degree of the animal exchange networks, which is a measure of the number of exchanges per herd. The two breeds with the highest average degree showed the lowest correlation. Information from the exchange networks was used to assign individuals to the genetic groups when molecular information was incomplete or missing to identify donors for a cryobank. Conclusions: A fine-scale picture of the population genetic structure at the herd level was obtained for the three breeds. Network analysis made it possible to highlight the influence of exchanges on genetic structure and to complete or replace molecular information in establishing a conservation program. © 2012 Dumasy et al; licensee BioMed Central Ltd
Genetic diversity and networks of exchange: a combined approach to assess intra-breed diversity
Abstract Background Cryopreservation of three endangered Belgian sheep breeds required to characterize their intra-breed genetic diversity. It is assumed that the genetic structure of a livestock breed depends mostly on gene flow due to exchanges between herds. To quantify this relation, molecular data and analyses of the exchanges were combined for three endangered Belgian breeds. Methods For each breed, between 91 and 225 sheep were genotyped with 19 microsatellites. Genetic differentiations between breeds and among herds within a breed were evaluated and the genetic structure of the breeds was described using Bayesian clustering (Structure). Exchanges of animals between 20, 46 and 95 herds according to breed were identified via semi-directed interviews and were analyzed using the concepts of the network theory to calculate average degrees and shortest path lengths between herds. Correlation between the Reynoldsâ genetic distances and the shortest path lengths between each pair of herds was assessed by a Mantel test approach. Results Genetic differentiation between breeds was high (0.16). Overall Fst values among herds were high in each breed (0.17, 0.11 and 0.10). Use of the Bayesian approach made it possible to identify genetic groups of herds within a breed. Significant correlations between the shortest path lengths and the Reynoldsâ genetic distances were found in each breed (0.87, 0.33 and 0.41), which demonstrate the influence of exchanges between herds on the genetic diversity. Correlation differences between breeds could be explained by differences in the average degree of the animal exchange networks, which is a measure of the number of exchanges per herd. The two breeds with the highest average degree showed the lowest correlation. Information from the exchange networks was used to assign individuals to the genetic groups when molecular information was incomplete or missing to identify donors for a cryobank. Conclusions A fine-scale picture of the population genetic structure at the herd level was obtained for the three breeds. Network analysis made it possible to highlight the influence of exchanges on genetic structure and to complete or replace molecular information in establishing a conservation program.</p
Appartenance locale et propriété au nord et au sud de la Méditerranée
Cet ouvrage, issu dâune rencontre entre des chercheurs travaillant sur des espaces gĂ©ographiques variĂ©s, de Tunisie, dâItalie, dâAlgĂ©rie, de France et de Turquie restitue, au plus prĂšs de lâexpĂ©rience des acteurs eux-mĂȘmes, les voies pratiquĂ©es pour acquĂ©rir et pouvoir revendiquer des droits dâappartenance. Dans ce processus, la propriĂ©tĂ© sâest rĂ©vĂ©lĂ©e ĂȘtre un terrain dĂ©cisif : ces Ă©tudes montrent Ă quel point, dans ces sociĂ©tĂ©s apparemment trĂšs Ă©loignĂ©es, lâaccĂšs diffĂ©rentiel aux biens ne dessine pas seulement des hiĂ©rarchies Ă©conomiques ou des primautĂ©s symboliques, mais crĂ©e des prĂ©rogatives qui investissent plus largement les individus. La faiblesse ou au contraire les privilĂšges qui dĂ©finissent lâappartenance Ă des groupes sexuels ou Ă des groupes dâĂąge sont largement charpentĂ©s sur des possibilitĂ©s diffĂ©rentielles de disposer de biens et de les transmettre. Et surtout, dans un large Ă©ventail de cas, la condition de « citoyen » ou de sujet dâun pouvoir central est Ă©troitement liĂ©e Ă la reconnaissance de cette capacitĂ© Ă transmettre. En somme, dans les sociĂ©tĂ©s modernes au nord et au sud de la MĂ©diterranĂ©e, ce recueil nous montre que le rapport aux choses crĂ©e des relations et des liens. Les capacitĂ©s dâexercice des droits de propriĂ©tĂ© dessinent les contours de communautĂ©s locales et, en consĂ©quence, celles de communautĂ©s territoriales plus vastes. Câest une approche originale Ă la « citoyennetĂ© » qui est prĂ©sentĂ©e ici, qui met en relief des aires « de compatibilitĂ© » entre des terrains dâanalyse apparemment trĂšs Ă©loignĂ©s. QuantitĂ© dâidĂ©es reçues sur les prĂ©tendues « spĂ©cificitĂ©s culturelles » caractĂ©risant ces diffĂ©rentes aires gĂ©ographiques sont ainsi mises en discussions ; ce qui ouvre un terrain de dialogue inattendu et fructueux. CrĂ©dits photo : Porta Palazzo, Turin, octobre 2014, Simona Cerutt
Le moment idéologique
Que peut nous apporter aujourdâhui la lecture des IdĂ©ologues, ces penseurs qui ont reconfigurĂ© le champ des savoirs au dĂ©but du XIXe siĂšcle ? La mise au jour dâun moment idĂ©ologique. Ce moment est celui qui voit une radicalitĂ© des LumiĂšres se scinder entre divers branchements disciplinaires, entre diverses conceptions de la subjectivitĂ© et de lâĂ©mancipation. Le moment idĂ©ologique est un moment de passage, mais surtout de dĂ©cantation. On y voit Ă©merger, quoiquâencore entremĂȘlĂ©s et solidaires, ce que nous sommes habituĂ©s Ă distinguer : LumiĂšres et romantisme, rationalisme et sentiment, radicalitĂ© et conservatisme, nĂ©cessitĂ© et volontarisme, colonialisme et soif dâaltĂ©ritĂ©, science et littĂ©rature. Les dix chapitres de cet ouvrage ont en commun de visiter ce moment idĂ©ologique Ă partir de questions concrĂštes, analysĂ©es sur des objets textuels prĂ©cisĂ©ment circonscrits : une fausse polĂ©mique, un cours dâhistoire, une analogie hydraulique, des thĂ©ories de lâimagination, des Ă©pisodes de rĂ©miniscence involontaire, un voyage Ă Alexandrie, un projet dâalphabet universel, une explication de lâamitiĂ©, une rĂ©Ă©criture romanesque de la folle « science des idĂ©es ». Câest Ă partir de ces cas particuliers que prend forme une image dâensemble du moment idĂ©ologique, oĂč se rĂ©vĂšlent Ă la fois la reconfiguration des champs du savoir et ce que cette reconfiguration a occultĂ© : lâinsĂ©parabilitĂ© de ce qui devient alors, dâun cĂŽtĂ©, « la littĂ©rature » et, de lâautre, « les sciences » (de lâhomme) â le moment idĂ©ologique nous faisant voir que ce sont les deux faces dâune mĂȘme piĂšce