Table 1.

Groups used in the analyses of ancestry comparisons and correlations of distortion. The location and ancestry composition of subgroups are indicated in Figure 1. The native genetic backgrounds possibly encountered are indicated for cases of introduction (n/a: not applicable)

Group	Native genetic background	Admixture pattern	Sub‐group	Populations used
Dock mussels	South‐Eu. M. edulis or Atl. M. galloprovincialis	Med. M. galloprovincialis / South‐Eu. M. edulis	havre cher stmalo brest stnaz	Port of Le Havre Port of Cherbourg Port of Saint‐Malo Bay of Brest Port of Saint‐Nazaire
F2	n/a	idem	F2	F1 female × F1 males
Backcrosses (BCs)	n/a	idem	BCG BCF1	gallo_med females × F1 males F1 female × gallo_med males
Norway admixed	North‐Eu. M. galloprovincialis (sometimes M. trossulus)	Atl. M. galloprovincialis / North‐Eu. M. edulis	LOF GAS	Lofoten Islands, Norway Gåseid, Norway
Naturally admixed	n/a	Atl. M. galloprovincialis / South‐Eu. M. edulis	ABD MCH JER HZSB	Aberdeen, Scotland Murchison oil station Jersey Island Mousterlin point (MOU) La Jument (JUM) Barres de Pen Bron (PEN) Chemoulin point (CHE) Groix Penestin (BIL_001) Le Pouliguen (POU_001) Houat Island (HOU_001)