In New Zealand, mice in reserves can complicate the control of mammalian predator invasion by masking scent and eating baits. Eradicating mice allows predator invasions to be more readily detected and managed, but removal of mice is only feasible if recolonisation is rare. We used genetics and morphology to assess whether the mouse population on Waikawa Island was isolated from the mainland population. A sample of mitochondrial DNA sequences revealed that at least four female mice must have founded the Waikawa population, but that gene flow between island and mainland mice is limited.
Introduced species are becoming part of the landscape around the world. Unfortunately, in many cases, the exact source population for these introduced species is not known, which can hamper their proper management. Genetic investigations can shed light on the introduction process and we used the New Zealand mallard (Anas platyrhynchos) population as a case study to demonstrate the insights that genetics can provide.