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Freshwater systems are among the most affected by the introduction of exotic species. The pumpkinseed sunfish Lepomis gibbosus, a centrarchid native to eastern North America, is listed among the top ten introduced freshwater fishes with the greatest ecological impact globally. Despite this, genetic and evolutionary studies of the species are still scarce. Here, we analyzed the genetic variability of introduced populations of L. gibbosus using three mitochondrial genes (COI, d-loop, and ND1). In addition, we used species distribution modeling to compare the niche of introduced versus native populations to assess the present and potential future distribution of the species under different climate change scenarios. Compared with the native populations, introduced ones present a lower level of genetic variability, indicating these populations originated from a small number of individuals from the native (Atlantic) population in the USA and Canada. The low variability was likely driven by a founder effect and subsequent bottleneck, as often occurs in invasive species. Our modeling results suggest not only that L. gibbosus modified its niche during the invasion process in Europe but also the possible global expansion of the species under future climatic conditions, which could facilitate its establishment in almost all continents. Full article

In recent years, ecological studies have highlighted the importance of niche in the invasion of new habitats by invasive species, stating that introduction into a similar niche is critical for rapid expansion into the new habitat. In this study, we focus on Lepomis gibbosus or Pumpkinseed sunfish, a centrarchid native to eastern North America that is among the top 10 introduced freshwater fishes with the greatest ecological impact globally. We compared their native and introduced niches in Europe based on occurrence data from three time periods (1900–1959, 1960–1989 and 1990–2021) using niche identity and background similarity tests. In addition, through MaxEnt software, we modelled present and future potential distribution of Pumpkinseed sunfish under climate change conditions. Our results show that L. gibbosus has significantly modified its niche in the process of invasion through Europe, highlighting the great adaptability of this species to higher temperatures and irregular water regimes. This niche differentiation clearly distinguished the European niche occupied by the invasive populations from the North-American-native niche, supporting previous studies that suggested that European L. gibbosus populations would not be able to survive in its native area. Our modelling results based on different future climatic conditions pointed out that temperature and precipitation are the most influential variables that could facilitate the establishment of sunfish on almost all continents. Globally, it is expected that Pumpkinseed sunfish will soon colonize the African continent, where there are already species that cohabit with this centrarchid. This reinforces the need to develop new prevention measures before its presence becomes irreversible, taking into account the role that climate change will play in its establishment. Full article