Good genes models of mate choice predict additive genetic benefits of choice whereas the compatibility hypothesis predicts nonadditive fitness benefits. Here the Chinese rose bitterling, Rhodeus ocellatus, a freshwater fish with a resource-based mating system, was used to separate additive and nonadditive genetic benefits of female mate choice. A sequential blocked mating design was used to test female mate preferences, and a cross-classified breeding design coupled with in vitro fertilizations for fitness benefits of mate choice. In addition, the offspring produced by the pairing of preferred and nonpreferred males were reared to maturity and their fitness traits were compared. Finally, the MHC DAB1 gene was typed and male MHC genotypes were correlated with female mate choice. Females showed significant mate preferences but preferences were not congruent among females. There was a significant interaction of male and female genotype on offspring survival, rate of development, growth rate, and body size. No significant male additive effects on offspring fitness were observed. Female mate preferences corresponded with male genetic compatibility, which correlated with MHC dissimilarity. It is proposed that in the rose bitterling genetic compatibility is the mechanism by which females obtain a fitness benefit through mate choice and that male MHC dissimilarity, likely mediated by odor cues, indicates genetic compatibility. K E Y W O R D S :Additive genetic benefit, female mate choice, genetic compatibility, good genes, mate choice, MHC, nonadditive genetic benefit, olfactory cues, Rhodeus ocellatus, sexual selection.

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Agbali, M. and Smith, C. 2012. Long-term fitness consequences for offspring of female oviposition decisions in the rose bitterling (Rhodeus ocellatus). -Acta Zoologica (Stockholm) 93: 367-372.Female oviposition decisions can have immediate consequences for offspring fitness as well as longer-term effects, either through irreversible disruption to normal development, inducing alternative adult phenotypes, or through 'coping' whereby challenges to development are compensated in the short term, but carry a fitness cost in the adult. We investigated the long-term impacts of oviposition decisions on offspring fitness parameters in the rose bitterling fish (Rhodeus ocellatus). Bitterling lay their eggs in the gills of living freshwater mussels, which complete development inside the mussel gill chamber. Bitterling embryo mortality in mussels is density dependent, and consequently, there are immediate costs associated with using mussels containing high numbers of eggs and embryos. We raised embryos at high and low densities for the first 4 weeks of development and then at a common low density until sexual maturity. Our results showed no effect of density on offspring survival or growth. However, there was an impact of density on age and size at maturity, with embryos raised at high densities becoming sexually mature earlier and at a smaller size. This effect may arise through embryos coping with low oxygen conditions during development. The results are discussed in the context of development and mating system evolution.