Demographic flexibility influences colonization success: profiling invasive fish species in the Danube River by the use of population models

Invasive species have the ability to modify their life-history traits in newly colonized areas, with positive shifts in specific life history traits under favourable environmental conditions. If such positive changes in their life history result in a comparably larger population growth rate, it may give them a competitive edge over native species, support faster range expansion and contribute to their invasion success. Within the present paper we hypothesized that the demographic flexibility represents an important contribution to the invasion success of exotic species, and that demographic flexibility patterns of invasive species differ from those in unsuccessful invaders. We tested this hypothesis by the use of elasticity analysis applied on simple age-structured population models of invasive fish species in the Danube River, as well as of non-native species that failed to establish or become invasive. Findings imply that the invasive fish species could have the ability to experience a more rapid population growth under favourable environmental conditions, especially those that sustain recruitment, while at the same time being more robust to changes in survival. The highest population elasticity among the assessed alien invasive species was detected in stone moroko (Pseudorasbora parva). The described approach has the potential to be used as an additional screening tool for invasive species. When combined with other invasion risk profiling methods, it can provide additional insight into characteristics of species invasions and in invasion potential of a species.