The viability, melanophore and embryo genesis of first- and second-generation hybrids between Paralichthys olivaceus and P. dentatus

In order to investigate marine flatfish distant hybridization performance, we compared the embryo development, pigment inheritance, and growth of Paralichthys olivaceus (Po), Paralichthys dentatus (Pd), their reciprocal hybrids (Po female x Pd male (Fo, original hybrid), Pd female x Po male (Fr, reciprocal hybrid)) and two backcrosses (Fo female x Po male, Fo female x Pd male). The results showed significant differences in prehatching performance, viability and melanophore patterns in the reciprocal crosses and two backcrosses compared to the parental controls. The embryo length surrounding the yolk for Fo x Po was only about 75%, followed by Po x Po, Pd x Po, Fo x Pd, Po x Pd, and Pd x Pd. High hatching rates were obtained in Po x Pd, Fo x Pd, Fo x Po, while in Pd x Po, the fertilization rate was significantly lower and larvae died at 4 dph. The morphology and distribution of melanophores of Po x Po, Pd x Po and Fo x Po belonged to one pattern, while, Pd x Pd, Po x Pd and Fo x Pd belonged to another, which indicated a typical paternal inheritance. This study systematically described the biological characteristics for interspecific hybrids of P. olivaceus and P. dentatus during their early development stages. These results would be useful for better understanding of distant hybridization in marine fish species.