Detecting Invisible Migrants: An Application of Genetic Methods to Estimate Migration Rates

In studies of migration, both between and within populations, it is not always feasible to use physical tags to track the movement of animals. Funding and time constraints may not allow for the trapping and tagging of a sufficiently large set of animals to expect that a reasonable number will be recaptured at a future time in another population. An alternative approach is to use genetic markers to estimate migration and population parameters of interest. This is a rapidly developing area of research, an advantage being that each captured subject has effectively been “tagged”. The choice of tag however is not at the discretion of the researcher, and is a realisation of a complex array of historical events and random fluctuations. It is therefore necessary to develop methods to interpret observed genetic characteristics in order to describe inter- and intra-population movements. We present research using simulated and real-world data which evaluates the performance of one recent genetic approach to handling these sorts of problems. The collected data is of an invasive species, where it is likely the populations from which the samples were taken were recently established and therefore did not meet the usual genetic equilibrium conditions.