Ecological traits and range size determine the occurrence of non-native fish species in a Neotropical floodplain

In this study, we assessed the invasion process of non-native fish species in the upper Paraná River floodplain using survey data from 1986 to 2018. We aimed to answer three questions: (1) whether the abundance of non-native species differed among lakes and rivers; (2) whether the probability of occurrence of non-native species differed among lakes and rivers over time, and (3) whether the probabilities of occurrence of non-native species are explained by their functional traits, phylogenetic relationships, or the area of native range. An analysis of covariance was performed to determine the differences in species abundance between habitats. The probability of occurrence for each non-native species was determined through logistic regression. To identify the factors that explain the probability of occurrence, the probability of occurrence at the first and last year of the sampled period was modelled as a function of the native range of the species and the axes from the ordinations of functional traits and phylogenetic relationships. Species abundance was highest in lakes, while the probability of occurrence of species was highest in rivers. Range size, functional traits of life history, and habitat use dimensions, positively affected the probability of occurrence of non-native species. The most important functional traits were offspring investment, egg size and fertilization type, defense, and shape factor.