Abstract
AbstractAimThe relationships between species and their landscape are important for understanding migration patterns. In fluvial systems, the complexity of the river network can strongly influence the dispersal and colonization rates of invading alien fishes, but habitat quality, species’ biological traits and their location of introduction are also potentially important. However, understandings of how these factors interact in the wild to influence the spatial distribution of invasive species over time are limited from empirical studies.Location“Virtual” and “real‐world” rivers from England and Wales.MethodWe developed an individual‐based model (IBM) to predict how these different factors influenced the invasion dynamics and population growth rates (as abundances) of nine “virtual” alien fishes over two timeframes (10 and 30 years). The alien fishes differed in their demographic (r‐ to K‐selected) and dispersal (fast to slow) characteristics and the rivers in their network complexity.ResultsIrrespective of river type, species and timeframe, the main drivers of both dispersal and population growth were the location of the introduction and the mean habitat quality of the patch into which the species were released. The introduction location determined whether dispersal was mainly passive in a downstream direction (faster) or active in an upstream direction (slower), with higher habitat quality then enabling faster population growth rates. Over 30 years, invasion rates were predicted to increase as the complexity of the river network increased, as this opened multiple invasion fronts where the invader traits favoured faster dispersal.Main conclusionsThis novel IBM revealed how the complexity of the physical environment interacts with the biological traits of alien species to influence invasion outcomes, with the location of the introduction and its habitat quality being the most important factors. These results thus substantially increase understanding of the factors that influence the dispersal and colonization rates of alien freshwater fishes.
Highlights
The relationships between animal movements and the structure of their environment are important to understand, with the variability in these movements driven both by species’ ecology and the spatio- temporal scale being considered (Roberts & Angermeier, 2007)
For some freshwater alien taxa, adaptations for persisting in temporary environments can assist their overland dispersal by passive or active means (Havel et al, 2015), such as the cryptobiosis of rotifers (Wallace & Snell, 2001). Their natural dispersal from invaded to uninvaded areas requires some level of fluvial connectivity (Gozlan et al, 2010), and while canals can provide movement corridors between river catchments (Hickley, 1986), movements and dispersal rates within catchments are dependent upon the structure and connectivity of the river network (Goldberg et al, 2010)
We applied an individual-based model (IBM) to predict how different river network configurations and habitat quality influenced the invasion of nine virtual alien fish that varied in their dispersal abilities and life-history traits, and by the location of their introduction into the network
Summary
The relationships between animal movements and the structure of their environment are important to understand, with the variability in these movements driven both by species’ ecology and the spatio- temporal scale being considered (Roberts & Angermeier, 2007). There are, considerable knowledge gaps on how the interactions of the spatial variability in river network complexity and habitat quality with the location of the release site influence the invasion success of alien fishes, especially across species of differing dispersal abilities and life-history traits While this is likely to relate to the complexity of these interactions and a lack of empirical data (Dominguez Almela et al, 2020), recent increases in computing power and the development of individual- based models (IBM) enable the use of predictive approaches to help overcome these knowledge gaps (Day et al, 2018; Rodríguez-Rey et al, 2019). | 3 are colonized faster than less branched networks through the formation of multiple invasion fronts; (b) the introduction location in the network influences the colonization rate, such that introductions in upstream locations result in more rapid colonization and population growth due to fish movements in a downstream direction into areas of higher stream order (and habitat quality); and (c) alien fishes with higher dispersal abilities and life-history traits that facilitate fast establishment (i.e. r-selected traits; Dominguez Almela et al, 2020) will colonize river networks more rapidly than fishes with the opposite suite of traits
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