Fig. 1

Production of oyster families with different level of resistance to Pacific oyster mortality syndrome (POMS). a Origin of genitors and production of the five biparental families. Four pairs of wild genitors were collected either in aquaculture (S+) or non-aquaculture (S-) areas on Atlantic (Atl.) or Mediterranean (Med.) coasts (blue and orange lines, respectively). The fifth pair of genitors (*) comes from a mass selection program (more details in method section). Genitors coming from aquaculture areas were assumed to be exposed to stronger selection pressure due to mass mortality outbreaks occurring annually at these sites. b Transplantation experiments. Oysters from the five families were raised in the hatchery under the same controlled conditions, and subsequently transplanted into the Thau lagoon either before (non-infectious period) or during a mortality outbreak (infectious period). c Survival curves for the five oyster families after transplantation into the Thau lagoon during the infectious period (a minimum of 125 oysters was used for survival tests). Day 5 corresponds to the end of the transplantation, when oysters were brought back to the laboratory. Resistant and susceptible oyster families are indicated by S+ and S-, respectively. **** p < 0.0001 (Mantel-Cox Log-rank test)