The evolution of eusociality through maternal manipulation

Eusociality is a fundamental phenomenon in many insects, yet its evolution and underlying mechanisms are still not clearly understood. Many analyses focus largely on worker altruism: offspring may forgo their own reproduction if the costs of this are outweighed by the inclusive fitness benefits of helping to raise close relatives. However, this offspring-centered approach often overlooks the potential fitness consequences to the mother, and thus there is potential to broaden this theory. Maternal effects are rife in nature, and consequently it is plausible that they could play an additional role in facilitating philopatry and helping behaviour, which may ultimately lead to the evolution of eusociality. To elucidate, we implemented an individual-based computational model whereby mothers are able to manipulate the body97size of their offspring by controlling larval diet provisioning. We anticipate that mothers may produce smaller daughters to coerce them into becoming non-reproductive helpers, as a smaller body size reduces their potential success of dispersing and reproducing alone. If such helping behaviour can also be facilitated by the manipulation of the mother’s offspring, helping to raise close kin could become less imperative and thus sociality may still evolve under lower levels of relatedness between offspring. To this end, we also investigate whether strict lifetime monandry (and thus higher relatedness between offspring)is a requirement for the evolution of eusociality via maternal manipulation. The results from this model provide key insights into maternal manipulation, a lesser-understood mechanism that can potentially facilitate helping behaviour in offspring and lead to reproductive division of labour, a critical step in eusocial evolution