SNP-based parentage analyses over two successive generations demonstrates the feasibility of efficient production of inbred lines in the Pacific oyster (Crassostrea gigas) by self-fertilization of simultaneous hermaphrodites despite severe inbreeding depression

The Pacific oyster, Crassostrea gigas , is a species in which true male and female well as hermaphrodite individuals have been reported. Among the latter, most are sequential, with one or more sex changes throughout their live, while few (<2%) simultaneous hermaphrodites (SH) may self-fertilize. Sex determinism its functional bases remain unclear this species. In study, SH oyster was found among mature broodstock used to produce progeny by self-fertilization. Several thousand offspring were obtained for family (SF1) but only 73 SF1 oysters survived following an episode of mass mortality at spat stage. Six them conditioned reproduction three be SH, produced limited viable self-fertilization (SF2). Oysters sampled genotyped 226 SNP markers, confirming that SF2 over two successive generations. To our knowledge, it second study reporting feasibility production on inbred line using primary genitor, first generate generations selfing. Observed mean inbreeding coefficient selfing 0.61, ranging from 0.46 0.80. This lower than expected theoretical value (0.8125), suggesting homozygous died early stages due depression. Our demonstrates lines can exhibit higher heterozygosity theoretically better survival heterozygous offspring. • Second evidence beyond larval progeny. Inbreeding rate expected.