Variation in the Vkorc1-gene and anticoagulant rodenticide resistance in Brown rats on the Faroe Islands

Anticoagulants are widely used to eradicate the invasive brown rat (Rattus norvegicus) on the Faroe Islands. In this study, we investigated variations in the rat Vkorc1-gene in these populations that could lead to resistance against these rodenticides.
In samples from 137 rats from the Faroe Islands, none of the earlier reported non-synonymous mutations in the Vkorc1-gene from Scandinavia, Belgium and Britain were found, but seven new ones were identified. None of those could be linked with functional resistance, but some have a potential based on their position in the enzyme. The calculated dN/dS ratio (0.81) suggests the Vkorc1 gene in Faroer is undergoing negative selection.
The low frequency in mutations and the dN/dS ratio suggest that resistance is not widespread and not spreading on the Islands. Further research is needed to link the newfound mutations with possible functional resistance.