Distinguishing the victim from the threat: SNP-based methods reveal the extent of introgressive hybridization between wildcats and domestic cats in Scotland and inform future in situ and ex situ management options for species restoration.

The degree of introgressive hybridization between the Scottish wildcat and domestic cat has long been suspected to be advanced. Here, we use a 35-SNP-marker test, designed to assess hybridization between wildcat and domestic cat populations in Scotland, to assess a database of 295 wild-living and captive cat samples, and test the assumptions of the test using 3,097 SNP markers generated independently in a subset of the data using ddRAD. We discovered that despite increased genetic resolution provided by these methods, wild-living cats in Scotland show a complete genetic continuum or hybrid swarm structure when judged against reference data.