A Genetic Tool for Better Management of Invasive Species

A technology based on computer simulations, which takes advantage of the heritability of certain genes across successive generations, could help improve the management of invasive species. A simulation was conducted using gray squirrel populations.   Invasive species are among the main drivers of biodiversity loss. They impact ecosystems, compete for food resources, occupy territories, and harm native species. Currently, methods for controlling these populations—such as trapping, poisoning, or hunting—are cruel, costly, and generally ineffective at addressing the scale of the invasion in most cases. To combat them more effectively, researchers at The Roslin Institute in the United Kingdom propose using genetic forcing or steering. This technology, based on genetic engineering, makes it possible to force a gene to be passed on—via sexual reproduction—with near certainty. Genetic forcing thus promotes the inheritance of a specific gene and increases its prevalence within a population. Based on the Cas9 protein (CRISPR-associated protein 9), this revolutionary technology can be used to add to, cut, or modify the DNA of an entire species in order to cause a drastic reduction in its population, for example by reducing its reproductive capacity. The applications are numerous. In theory, it can limit the spread of disease-carrying insects, control invasive species, or eliminate resistance to herbicides or pesticides in certain organisms. For safe and effective deployment, it is essential that a genetic force be both self-limiting and capable of overcoming evolutionary resistance. The researchers therefore used computer simulations to test HD-ClvR, a new combination of CRISPR-based genetic constraints that eliminates resistance and localizes the area of spread. The approach, known as direct inheritance of gender bias (DIGB), could be used to spread a female infertility gene within a targeted animal species in regions where it causes harm. Over time, this would lead to a shortage of fertile females and a decline in the invasive population solely within these targeted areas. As an experiment, the researchers modeled HD-ClvR in the gray squirrel (Sciurus carolinensis), an invasive species in the United Kingdom that competes with the red squirrel and is responsible for both biodiversity and economic losses. The results show that HD-ClvR could reduce a targeted population of gray squirrels by more than 60% in ten years, with the potential to completely eliminate these rodents from specific areas within twenty years. This approach would therefore allow for the effective control of an invasive species, with little risk to other species. HD-ClvR thus proves to be an effective genetic tool for managing invasive species. The researchers hope to apply this promising solution to other non-native exotic species.