Is there more in ‘gamete quality’ than quality of the gametes? A review of effects of female mate choice and genetic compatibility on offspring quality

Zygote quality is a major issue in production aquaculture, and has been considered, for example, in terms of lipid content, readiness of the female spawner, potency of the male spawner and other issues. In the mean time, evolutionary biologists have been considering issues of mate choice and genetic compatibility of the parents. This paper gives an overview of the main hypotheses of female mate choice, the reasons for multiple mating of females and their potential effects on offspring quality. I suggest how these ideas, if taken into account in commercial aquaculture, might increase the value added of several species in commercial aquaculture, which is impeded by poor offspring quality. Theoretical and empirical research shows that females in general choose partners actively among different males and that females often mate with multiple males. Both active mate choice and multiple mating improve the quality of the offspring, for example as enhanced survival and growth. Active female choice also occurs at the gamete level, and according to the ‘cryptic female choice hypothesis’, eggs are able to affect which sperm from which male will be fertilized. Several proximate mechanisms regarding how the eggs can affect the sperm have been demonstrated. Improved offspring quality of active female choice, cryptic female choice and multiple mating are all in accordance with the ‘genetic incompatibility hypothesis’. This hypothesis states that the quality of the offspring depends on the degree of intragenomic conflicts due to interactions between maternal and paternal haplotypes, for example as increased immunity against a wider range of pathogens when choosing a mate with different immune‐coding alleles than your own. According to the genetic incompatibility hypothesis, eggs from a particular female are expected to do well when fertilized by a particular male, whereas eggs from the same batch from the same female should do poorly when fertilized by other males. Such sire–dam interactions have been demonstrated empirically. I argue that if such a sire–dam interaction is a general phenomenon, this might have major implications for the commercial aquaculture industry, concerning choice of number of brooders, fertilization method, methods to preserve gametes, spawning protocols and breeding programmes.