Evolutionary genetics of translocated island populations of birds: data and opportunities

Species’ declines around the globe have reached such a rapid rate that without the implementation of extreme conservation methods, we are likely to witness the next mass extinction. Translocation is a popular and growing conservation technique, especially to islands. However, despite the widespread use of this method, the long-term genetic outlook of populations established on islands (namely those with small carrying capacity, and isolated from other populations) is often poorly quantified, and there are conflicting data supporting the relative roles of evolutionary processes such as drift, balancing selection, directional selection and genetic purging. Taking examples from avian translocations, this paper reviews recent data on the genetic dynamics of island populations established for conservation purposes. The goal of conservation genetics is to preserve species’ adaptive potential for the long term. In general, population bottlenecks cause losses of genetic diversity, but there is mixed evidence for the importance of other evolutionary processes, such as maintenance of genetic diversity by balancing selection. There is a clear need for long-term studies that test for associations between genetic change and success of populations established via translocation to conservation islands, and for integration of these observations with ecological and climate data. Combining data types into the future will provide a holistic view on the interactions between the role selection plays, how island populations established by translocations may respond, and how this information can improve conservation strategy.