Widespread Hybridization between Invasive Bleak (Alburnus alburnus) and Iberian Chub (Squalius spp.): A Neglected Conservation Threat

Hybridization between native and nonnative fish species is a major conservation issue, especially in ecosystems with high levels of endemism, such as Iberian streams. To date, hybridization the invasive bleak Alburnus alburnus has been reported for chub Squalius alburnoides S. pyrenaicus scattered locations only. However, spreading region, potentially increasing risks other species. gather more comprehensive picture on current geography hybridization, we compiled records hybrids Portugal conducted genetical assessments carolitertii. We found that widespread throughout Portuguese river basins involves at least alburnoides, may not only cause waste reproductive effort damage genetic integrity these endemic but also promote shifts dynamics hybrid complex, which includes individuals various ploidy combinations parental genomes, reproducing sexually asexually. recommend future studies characterize fitness their ecological interactions fish, order to design effective measures.