Mate selection in captive-breeding rockfishes Sebastes spp.: inference from parentage analysis and the major histocompatibility complex (MHC)

Rockfish species of the genus Sebastes are notable for being numerous and diverse. Rockfishes are unusual among fish because they fertilize their eggs internally and release live, swimming larvae. They undergo complex courting behaviors, which may allow females to be selective about their mates. The major histocompatibility complex (MHC) is implicated as having an important influence on mate selection in other fishes, especially in sticklebacks and salmonids. Research suggests that females choose mates that optimize the MHC genotypes of their offspring. Previous research on rockfishes indicates that multiple functional MHC sequences may be found in each species, and that multiple mating is common in the genus, possibly as a bet-hedging strategy against uncertain or incomplete mate-selection information. In this project, we characterized the MHC genotypes of copper (S. caurinus) and quillback (S. maliger) rockfish parents, assessed parentage of 14 larval broods, and assessed the MHC genotypes of the parents to determine if MHC-mediated mate choice was occurring. As in previous studies, we found that rockfishes possess multiple, highly variable MHC genes, and that females may mate with multiple males. We also found evidence of female preference for particular males. However, we found no strong evidence of selection based on MHC genotype. Females were not consistently selective based on relatedness, allele count, proportion of shared alleles, or minimum, mean, or maximum DNA or amino acid genetic distance. Instead, it appears that females were selective based on other measures of mate quality not considered in this study, with some hedging of bets through multiple mating also occurring.