Accounting for intraspecific variation to quantify niche dynamics along the invasion routes of Drosophila suzukii

Biological invasions are one of the main threats to biodiversity worldwide, and understanding the mechanisms allowing invasive species to colonize their new environments is critical to the management of invasive populations. One particular aspect of invasion biology is to define the environmental conditions within which invasive species can persist (i.e. their ecological niche) to get insights on the potential role of adaptation in successful invasions, as well as to predict future invasion. Here, we use multiple correlative species distribution models and metrics of niche expansion and stability to investigate the worldwide invasion of the spotted-wing drosophila, Drosophila suzukii. By modeling the climatic niche of D. suzukii from occurrence data in its native and invasive ranges, we tested if a shift in the realized niche has occurred during invasion. Furthermore, we use recent population genetics work on the invasion history of the species to test whether invasive populations have preferentially invaded areas with climatic conditions more similar to the ones in their precise area of origin. Overall, our results show that D. suzukii displays a wide climatic niche and suggest that the species' success in the invaded ranges may result from the absence of environmental challenges upon colonization. Furthermore, we show that the use of different geographical backgrounds can impact the outputs of niche comparisons and advice using complementary methods in the study of niche dynamics during biological invasions.