Longitudinal reconfiguration of multifaceted fish α and β diversity triggered by non-native species invasion in tropic rivers of Hainan Island.

Human-mediated fish invasions have reconfigured the native fish faunas throughout the freshwater ecosystems worldwide. Beyond the well-documented homogenization reported in temperate basins, our knowledge on how multifaceted biodiversity response to fish invasions in tropic rivers remains poorly understood. It is also hanged in doubt that how fish invasions modify the longitudinal patterns of fish faunas under the concept of river continuum. Here, we applied one-way permutational multivariate analysis of variance to test how fish invasion influenced the longitudinal patterns of multifaceted α and β diversity of fish assemblages in three largest rivers of Hainan Island, China. Meanwhile, we employed multiple regression analysis to examine the relationships between the invasion degree and multiple α diversity indices as well as functional traits of native fishes. We found non-significant longitudinal variations for all multifaceted α diversity for native fish assemblages. However, our results demonstrated significantly longitudinal variations for multifaceted overall β diversity and its turnover components to the upstream-downstream gradient. Considering the consequence of non-native species invasion, we recorded tough homogenization in all the multifaceted aspects, as all the overall β diversity and its turnover components were concurrently significantly decreased after invasions. In comparation with upper reaches, the middle-lower reaches exhibited more significant homogeneous patterns incurred by invasions. In terms of biotic acceptance/resistance hypothesis, we found native fish faunas with higher richness, evenness and trophic level tented to resistant invaders, whereas with even phylogenetic compositions and late maturation showed acceptance to invasions.