Strategies to address the conservation threats posed by hybridization and genetic introgression

Hybridization poses a complex problem for biodiversity conservation but there has been little discussion of strategies and guidelines designed to address it from a management perspective. In this article I review management approaches aimed at addressing hybridization while highlighting outstanding needs. Despite real-world efforts to manage systems in which hybridization is a concern, there has been little effort to develop broadly applicable guidelines or best management practices. Management programs would be enhanced by the characterization of the patterns and processes of hybridization in nature and integrating those into planning and policy. Doing so facilitates the development of holistic strategies that balance the importance of hybridization in many biological systems while addressing situations in which human-facilitated gene flow causes concern. The shift from reactive management to emphasizing measures designed to prevent hybridization from becoming a threat has been a positive development. Examples include assessing the genetic characteristics of populations used in translocation programs. Overlooked, however, has been the management of stable hybrid systems in which the goal is not necessarily preventing intermixing but protecting stabilizing mechanisms through policy and land use management. When hybridization emerges as a legitimate threat, activities such as culling, spatial isolation, targeted harvest, and de-introgression can protect threatened genomic units. Further experimentation of these techniques and collaboration among scientists and managers will provide lessons for establishing general guidelines for the conservation community. I hope this review stimulates discussion about approaches useful for addressing hybridization and promotes further development of new techniques and frameworks.