Résumé
The alpine grouse (Lagopus muta) and the grey partridge (Perdix perdix) reaches in Pyrenees the Southern limits of their areas of world distribution. The Pyrenean populations of these two subspecies (Lagopus muta pyrenaica and Perdix perdix hispaniensis) are thus in situation of biogeographical isolate. Both sorts(species) are excellent bio-indicators of the evolution of the open circles of height. Under the combined pressure of the environmental and anthropological requirements, these circles know at present a sensitive evolution characterized by an altitudinal increase of the levels of vegetation and thus a shrinkage of the available housing environment for the species of height. The regression of the agro-pastoral activities stresses this phenomenon generalized by reforestation of the circles. A consequence expected from these upheavals is the increase of the degree of fragmentation of housing environments in particular for the populations of height. Beyond the influence of the landscape on the structuring of the populations, another factor could structure the populations of partridges grey: individuals' releases of breeding in wild populations. In this thesis, we are interested in the genetic structuring of the alpine grouse of Pyrenees and grey partridge in France to help in the decision of the plans of preservation.