Table 3. Genotypic diversity of stolbur genes secY, stamp and vmp1 in four predefined European regions, (1) the host-shift population Germany, (2) a putative transition population Switzerland, and the two putative regions of origin, (3) Italy and southern France, and (4) Slovenia and Croatia.

Gene	Region	Number of isolates tested	Number of genotypes	Nucleotide diversity	Mean number of pair-wise differences
secY	Germany	13	1	0	0
	Switzerland	17	1	0	0
	Slovenia/Croatia	9	2	0.00027	0.22
	Italy/France*	23	3	0.00325	2.69
stamp	Germany	12	1	0	0
	Switzerland	5	1	0	0
	Slovenia/Croatia	10	3	0.00097	0.56
	Italy/France*	14	6	0.01028	5.88
vmp1	Germany	13	2	0.00012	0.15
	Switzerland	16	2	0.00010	0.13
	Slovenia/Croatia	11	2	0.00050	0.66
	Italy/France*	14	10	0.00979	12.69

The region Switzerland includes Swiss samples north and west of the Alps. The region Italy/France includes samples from the Swiss canton Ticino, situated south of the Alps and part of the Italian Po Basin. The gene stol-11 was monomorphic in tuf-a stolbur and not included. Genotype frequencies are shown in Appendix S3.

^*includes the Swiss canton Ticino south of the Alps.