Résumé
Background: Biological invasions are a major component of global change. Yet it remains unclear why some introduced populations become invasive while others do not. One intriguing hypothesis is the purging of deleterious mutations during the introduction process. Following the introduction of a small number of individuals into a new area, the interplay between genetic drift, inbreeding and naturalselection may lead either to the fixation or to the purging of deleterious alleles, affecting individual fitness. We hypothesize that populations that successfully become invasive are those that have purged part of their genetic load.Materials and Methods: We investigate the purge hypothesis across a broad taxonomic scale, analyzing ten insect species with well-documented invasion histories. For each species, we sampled between five and ten key native and invasive populations, representative of major steps in their invasion routes. We performed whole-genome pool-sequencing and developed a reproducible analysis pipeline to identify, annotate and categorize hundreds of thousands of SNPs per species. This framework enables a quantitative comparison of genetic load between native and invasive populations, and between species.Results: As expected, genetic diversity is generally lower in invasive populations compared to native ones, reflecting historical bottlenecks associated with introductions. However, we observe strong interspecific variation in the severity of bottlenecks and the magnitude of genetic load. Across species, no consistent trend emerges regarding the evolution of genetic load: some invasive populations show patterns compatible with purging, while others appear to have accumulated deleterious alleles. These contrasting patterns highlight the complexity of evolutionary trajectories during invasions.Conclusions: Our multi-species comparative approach suggests that the dynamics of genetic load during invasions are highly context-dependent. While purging may contribute to invasion success in some species, it does not appear to be a systematic outcome. Ongoing work will refine these findings and explore whether specific subsets of genes are more likely to undergo purging. These results emphasizethe need for a more nuanced understanding of how demographic and selective forces interact during biological invasions.