One of the greatest unmet issues in conservation biology is the genetic management of fragmented animal and plant populations. Many species across the planet have fragmented distributions with some small isolated populations that are potentially suffering from inbreeding, loss of genetic diversity, and elevated extinction risk (genetic erosion). Fortunately, these effects can usually be remedied by augmenting gene flow (crossing populations within species), but this is rarely conducted. Disturbingly, evidence of any genetic differentiation among populations typically leads managers to conclude that the populations should be kept isolated, thereby dooming many to eventual extinction. We are particularly concerned with populations fragmented by human actions in the last 500 years, encompassing most of the impacts arising from a 13-fold increase in the human population.