Table 2. Results of partial Mantel test, investigating the effect of clusters (A1.1, other A1, A2 for type A; B1, B2 for type B) on genetic differentiation when correcting for geographical distance.

group	variable	Mantel r	p1
A (Rhine)	waterway distance	0.76	0.0013**
A (Rhine)	cluster	0.31	0.0009***
B (Rhine)	waterway distance	0.48	0.7266
B (Rhine)	cluster	0.84	0.0001***

¹***P<0.001; **P<0.01.