Pii: S0006-3207(98)00066-4

Understanding the evolutionary role of gene ̄ow is pivotal to the conservation of endangered populations. Gene ̄ow can be enhanced through population translocations that are conducted to maintain genetic variation and combat the negative consequences of inbreeding depression (two of the major concerns in the conservation of subdivided or isolated populations). While researchers have given extensive consideration to the idea that gene ̄ow can act as a creative evolutionary force by maintaining genetic variation or spreading adaptive gene complexes, the focus of this paper is to investigate gene ̄ow as a force that constrains local adaptation. I brie ̄y review the theoretical basis of and summarize empirical studies that indicate gene ̄ow can constrain local adaptation, and may thereby lower short-term population ®tness. This review suggests that knowledge of gene ̄ow rates and understanding ecological di€erences among populations is necessary before embarking on a program to arti®cially enhance gene ̄ow. # 1998 Elsevier Science Ltd. All rights reserved.