Introduction

Genetic management of fragmented populations is one of the major, largely unaddressed issues in biodiversity conservation. Many species across the planet have fragmented distributions with small isolated populations that are potentially suffering from inbreeding and loss of genetic diversity (genetic erosion), leading to elevated extinction risk. Fortunately, genetic deterioration can usually be remedied by augmenting gene flow (crossing between populations within species), yet this is rarely done, in part because of fears that crossing may be harmful (but it is possible to predict when this will occur). Benefits and risks of genetic problems are sometimes altered in species with diverse mating systems and modes of inheritance. Adequate genetic management depends on appropriate delineation of species. We address management of gene flow between previously isolated populations and genetic management under global climate change.