Symposium: “Socio-reproductive conflicts and the father’s curse dilemma”
Mikael Mokkonen, Esa Koskela, Tanya Procyshyn, and Bernard Crespi (Aug 2018)
Choice of mate has important implications for the survival and future reproductive success of offspring
The zero-sum game of life
Successful reproduction involves finding a suitable mate, investing in offspring during its development, and then caring for the offspring after it is born. Females typically invest more in offspring through pregnancy and postnatal care, whereas males typically impact offspring indirectly through genetic effects. Such asymmetry between the sexes during reproduction results in sexual conflicts of interest over traits associated with mating and parental efforts.
Focusing on mammals, and specifically on the well-studied bank vole (Myodes glareolus), Mokkonen and coauthors draw on studies from evolutionary ecology, endocrinology, and genetics to synthesize a new concept known as the father’s curse dilemma, which describes an evolutionary trade-off between quality of parental care and offspring quality. The authors have gathered evidence that trade-offs between mating and parenting can be mediated by the same genes, with different fitness effects in females compared to males. At the heart of the father’s curse dilemma is the finding that those genes that make females good parents are likely to render offspring, particularly males, less competitive later in life as adults. Thus, fathers are faced with a dilemma: Is it better to find a mate that will ensure better survival of offspring during parental care or a mate that will confer genes that make the offspring more competitive later in life?
Evolutionary conflicts between males and females can manifest over sexually antagonistic interactions at loci, or over sexually antagonistic interests within a locus. The latter form of conflict, intra-locus sexual conflict, arises from sexually antagonistic selection and constrains the fitness of individuals through a phenotypic compromise. These conflicts, and socio-reproductive interactions in general, are commonly mediated by hormones, and thus, predictive insights can be gained from studying their mediating effects. Here, we integrate several lines of evidence to describe a novel, hormonally-mediated reproductive dilemma that we call the father’s curse, which results from an intra-locus conflict between mating and parental efforts. Essentially, a genetic locus exerts pleiotropic and antagonistic effects on the mating effort of one individual, and parental effort of a related individual who is the primary provider of parental care. We outline the criteria for operation of the father’s curse dilemma, provide evidence of the phenomenon, and discuss the predictions and outcomes arising from its dynamics. By integrating the effects of hormones into socio-reproductive conflicts and socio-reproductive effort, clearer links between genotypes, phenotypes and fitness can be established.