TABLE 1.

Geographic regions used in genetic diversity and differentiation analysis of UK Eurasian otters (Lutra lutra).

RBD region	Included river basin districts (RBDs)	N	Land area (km2)
Eastern	Anglian, South East, Thames	74	50,226
Northern	Humber, North West, Northumbria, Solway Tweed	59	61,601
Severn	Severn	84	21,056
South West	South West	77	18,191
Western Wales	Dee and Western Wales	102	14,715
Other	Ireland and Scotland	11	NA

Note: RBD: Regions are based on amalgamations of River Basin Districts (RBDs) as defined in the Water Framework Directive Cycle 2 (Environment Agency, 2015; Natural Resources Wales, 2015), N is the number of otters genotyped and Land Area is the total km² of land within an RBD region (no Land Area is provided for the ‘other’ RBD region as it covers a vast and unconnected area of land with very few samples).