Résumé
Biological invasions are a major component of contemporary global change. However, our knowledge of the evolutionary and ecological processes underlying biological invasions remains limited. The main goal of this thesis is to increase our knowledge of such processes, through the study of an invasive ant species, Wasmannia auropunctata. To this aim, we studied the genetical and behavioural characteristics of different populations of the native and introduced range of the species, as well as the properties of their habitats, and conducted laboratory experiments. Our results showed the coexistence of two different reproduction systems (clonal/sexual) in W auropunctata. Contrary to expectations drawn from the litterature, invasive populations have been found in the native range of the species, and their invasiveness is explained neither by their reproduction system, nor by their social organization, but rather by the perturbation of their habitat due to human land use. The clonal reproduction system of W. auropunctata seems however to play an indirect role in its invasive success by maintaining over lime specific combinations of genes that may allow the species to settle in anthropized habitats. A laboratory experiment confirms that the workers of clonal populations are more tolerant to the hot and dry abiotic conditions observed in the human-modified habitats than the workers of sexual populations. This study illustrates the importance of the eco-evolutionary processes taking place in the native range of invasive species, the major role of human activities in driving at least sorne of these processes, and the adaptive potential of clonal reproduction systems.