Table 1. Origins of the Eurasian and Japanese otters used in this study.

	Sample	Subspecies	Studbook number or voucher	Sex	Locality	Sample type	Seq. approach	Accession No.
Eurasian otter(Lutra lutra)	EO1	unknown	#32	Male	unknown	frozen muscle	MPCR + direct sequencing	LC049953
	EO2	unknown	#35	Male	unknown, China	frozen muscle	MPCR + direct sequencing	LC049378
	EO3	L. l. chinensis	#39	Male	Sichuan, China	frozen muscle	MPCR + direct sequencing	LC049952
	EO4	unknown	#52	Female	unknown, China	frozen muscle	Long range PCR + direct sequencing	LC049377
	EO5	unknown	NMNS-CA209	unknown	Sakhalin, Russia	dried tissue	MPCR + direct sequencing	LC049954
Japanese otter	JO1	unknown	YCM-M0001	unknown	Kanagawa, Japan	dried tissue	Illumina	LC049955
	JO2	unknown	NZP-SS-01	Male	Kochi, Japan	inner part of paw pad	Illumina	LC050126
	JO3	unknown	unknown	unknown	Fukushima, Japan	dried tissue	Illumina	undetermined

The studbook numbers come from the Internal Studbook of the Eurasian Otter (Lutra lutra) for the Japanese Association of Zoos and Aquariums (JAZA). NMNS-CA: National Museum of Nature and Science, Comparative Anatomy collections. YCM-M: Yokosuka City Museum, Mammal. NZP-SS: Noichi Zoological Park, Stuffed Specimen.