What are the benefits and risks of gene drives for population management and conservation biology?

Gene drive has recently been proposed as a promising technology for population management, including in conservation genetics; it is based on the release of genetically engineered individuals designed to rapidly propagate a desired mutation or transgene to high frequencies in wild populations. Potential applications in conservation biology include the control of invasive pest populations that threaten biodiversity (eradication and suppression drives), or the introduction of beneficial mutations in endangered populations (rescue drives). We examine the challenges posed by the evolution of resistance to gene drives and review the various environmental risks associated with gene drives. Contrary to suppression and eradication drives, the evolution of resistance should not prevent the fixation of rescue drives, while countermeasures to stop their spread are likely to fail. For eradication and suppression drives, minimizing the chances of resistance evolution requires targeting genes whose sequences have low polymorphism in natural populations (e.g. that are functionally constrained), which might however increase the odds of gene drive propagation to non-target populations/species. Conversely, targeting sequences that are present in the target population/species, but absent in non-target populations/species, might increase the odds of resistance evolution due to the introgression of resistant alleles from non-target populations/species. Once a gene drive has fixed in a target population, the time it persists before being inactivated by mutations influences its risk of spread to non-target populations/species. Finally, ethical values along with a clear regulatory framework for risk assessment should guide gene drive research.