An Individual-Based Simulation Model to Guide the Conservation of Native Species Threatened By Introgression

We present here an individual-based model that simulates the spread of non-native genes across river networks. This spatially-explicit model accounts for (a) system-specific patterns of landscape connectivity and habitat quality; (b) realistic population demographics; (c) genetically driven fitness and behavioral differences among native, non-native, and hybrid individuals, and; (d) the stochasticity involved in individuals’ survival, movement, mate selection, and genes’ inheritance. The model simulates mate selection, reproduction, dispersal, and survival of each simulated individual, while keeping track of its genetic composition (using a used-defined number of species-diagnostic markers) and its location. The individual-based nature of the simulations allows users to collect multiple samples from simulated fish populations, which can then be compared to identify the most effective collection strategy to be used in the field. Moreover, by allowing researchers and managers to conduct simulations tailored to the system and the species of interest, this model has the potential to interpret observed patterns of introgression across river networks, thereby increasing our ability to manage and protect native fish populations threatened by introgression with non-native genes.