Shifts in species traits among North American freshwater fish assemblages: ecological homogenization?

Abstract

This study examines whether the processes of species invasion and extirpation have produced distinct shifts in mean species traits of North American freshwater fish assemblages. An analysis of 54 species (29 invaders, 25 extirpated taxa) in 7 drainages revealed significant differences in maximum length, native latitudinal range size, habitat specificity, and migratory behaviour. Results suggest a pattern in which extirpated species are being replaced by larger, more environmentally tolerant species capable of occupying a broader range of habitats. Freshwater fish assemblages containing introduced generalist species may have a selective advantage over pristine communities as human-dominated landscapes continue to replace natural systems.