Abstract
Since parents face a trade-off between current and future reproduction, each should prefer to save its own resources and leave the majority of offspring care to its partner. For several decades, evolutionary biologists have focussed on understanding how this fundamental evolutionary conflict drives the extensive variation in parental care forms we see in nature. But is parental conflict inevitable, as is usually assumed? What factors determine its intensity? We need to understand whether and how parental conflict varies before we can test whether it indeed shapes the evolution of parenting behaviours. Currently, this goal is hampered by a lack of reliable ways to measure parental conflict. I propose that comparing levels of the ‘parenting hormone’ prolactin can give new insights into each parent’s intention to care and thus the extent to which partners disagree about who should provide care and in what quantity. I will use prolactin to assess the (1) causes and (2) consequences of variation in parental conflict in speckled mousebirds Colius striatus. My recent pilot work demonstrated that this species is highly suitable to: (1) Assess what factors determine the degree of parental conflict over care. Mousebirds live in stable social groups and many factors, such as the degree to which parents rely on each other for their continued survival, present exciting opportunities to investigate how and why parental conflict varies. (2) Test whether and how parental conflict influences each parent’s eventual investment. I will experimentally manipulate conflict to test whether this influences the eventual investment that each parent makes. By unravelling the causes and consequences of parental conflict, this project will help to move forward our understanding of the fascinating ways in which parental care evolves in the light of conflicts between carers.
Netherlands