During my PhD, I investigated invasion biology. During the last century, the number of biological invasions has been growing due to human activities. The processes underlying biological invasion remain however poorly known. The biology of invasions lacks a unifying theoretical framework. To fill this gap, I decided to study invasions through an evolutionary framework. More specifically, I focused on the invasions of freshwater biota of the New World (especially the Martinique island) by several Thiarid snails, using three approaches relevant to different time scales. (i) A phylogeographical approach provided evidence for repeated recent introductions of Thiarids in the New World, probably linked to the trade of aquarium plants. (ii) Relationship between life-history traits and invasive abilities was studied by combining field data and a quantitative genetics experiment. This revealed that the replacement of invasive taxa is shaped by natural selection. The invasive abilities of a taxon are strongly correlated to its position along the trade-off "fecundity-birth size". Moreover hybridization can improve invasive abilities through an heterosis effect on life-history traits. (iii) The spread of the invaders following introduction was studied by a metapopulation-based model, taking into account both landscape fragmentation and the intrinsic stochasticity of biological invasions. This model was then successfully applied to a 12-year presence/absence dataset describing the spread of Tarebia granifera in Martinique. Thanks to these approaches, I acquired an accurate comprehension of the invasive process of Thiarid snails and envisaged possible generalizations. My post-doc research project dissects the mating behaviour of the hermaphrodite snail Physa acuta. This species suffers from strong inbreeding depression. I thus assess whether it is capable of inbreeding avoidance and whether sex-specific behaviours exist even in this hermaphroditic species. Because some populations go through recurrent bottlenecks, among-population heterosis could also be common in this species. I thus test whether these snails are able to distinguish between sympatric and allopatric sexual partners. In particular, do they preferentially mate with snails from allopatric populations? In a second experiment, the effects of proximal factors, such as population density, body size and mating history, on mating behaviours are studied. Finally to investigate the potential for selection to shape mating behaviours in this species I am starting an artificial selection experiment on the age at first reproduction.