Climatic niche shift of aquatic plant invaders between native and invasive ranges: a test using 10 species across different biomes on a global scale

Environmental niche conservatism defines a concept, stating that species could live in the same environmental condition in both native and invasive ranges. Niche modeling often used this as basis for the prediction of the range of invasive plants. However, it is debatable whether environmental niches of invasive plant species are conserved or shift between native and invasive ranges. Only few studies have investigated such a shift in aquatic plant invaders (APIs) on a meaningful global scale. Environmental niche modeling was used to project climatic niche distributions of 10 APIs based both on the native range and the invasive range of species. We found that niche shifts of APIs between native and invasive ranges may occur throughout the world. Moreover, we found niche shifts of APIs between native and invasive ranges across different biomes. The largest climatic niche shift was detected for Najas minor and the smallest for Alternanthera philoxeroides. For all 10 APIs, overlap between both ranges was maximal for large river deltas, while overlap was minimal for temperate floodplain rivers and wetlands. For APIs, the suitability of the climatic habitat was highest in temperate coastal rivers for invasive models in invasive ranges. More importantly, based on invasive models, climatic suitability was significantly higher for temperate coastal rivers and temperate floodplain rivers and wetlands in invasive ranges and compared to native models. We suggest to integrate climatic niches of both native and invasive ranges into projections of the global climatic niche distribution of APIs.