Incorporating evolutionary processes into a spatially-explicit model: exploring the consequences of mink-farm closures in Denmark

In this paper, we present an individual-based cellular lattice model, which is based on a real landscape (Denmark). The model predicts the distribution of free-ranging mink from data collated on the geographic locations of fur farms, the number of breeding mink kept per farm, and a range of parameters regarding escape, reproduction, mortality, and dispersal. When evolution was incorporated in the model, the results showed that the degree of adaptation within the free-ranging mink population is likely to vary spatially, with lower adaptation in areas where farm mink density is highest (due to the greater number of escaping mink). We used the model to explore the potential consequences of closing mink farms, or limiting escapes from them, on the evolutionary ecology of the free-ranging population and found that depending upon the paramaterisation of the evolutionary processes, several different outcomes are possible. Closing mink farms may result in a crash of the free-ranging population, or alternatively it may result in the establishment of a better-adapted, truly feral population that may ultimately outnumber the population that was present before farm closures. The main purpose of this paper is to raise awareness of the potential importance of evolutionary processes for the naturalisation of mink in Denmark. and to highlight the need for further work. Future field studies should be targeted to reduce the uncertainty in key parameters, allowing the development of an improved version of this model that can be used to generate management recommendations. More generally, we believe. that further work linking evolutionary and population biology is required particularly in an applied context. There are likely to be many further scenarios where evolutionary processes may hold the key to understanding both population and community dynamics.