Parent\u2013offspring conflict and its outcome under uni-and biparental care

Jacqueline Sahm,Sandra Steiger,Madlen A Prang

doi:10.1038/s41598-022-05877-6

Abstract

Conflicts over parental investment are predicted to be common among family members, especially between parents and their offspring. Parent–offspring conflict has been studied in many brood-caring organisms, but whether its outcome is closer to the parental or offspring optimum is usually unknown, as is whether the presence of a second parent, a caring male partner, can affect the outcome. Here, we manipulated the initial brood size of single and paired female burying beetles to examine how many offspring are necessary to maintain parental care in the current brood. We found that mothers continued to invest in small broods even if their reproductive output would have been higher if they had discontinued their care and produced a second brood instead. Consequently, our data suggests that the offspring have the upper hand in the conflict. However, our results further show that paired females laid a second egg clutch more often and produced more offspring than single females, suggesting that the presence of a male partner shifts the conflict outcome towards the parental optimum. This latter result not only is a novel aspect of parent–offspring theory, but also represents an additional factor that might explain the evolution of biparental care.

Highlights

Conflicts over parental investment are predicted to be common among family members, especially between parents and their offspring
Two different sorts of parent–offspring conflicts are known from theory, namely the intra-brood conflict, in which parents and offspring battle over resource allocation among members of the current brood, and the inter-brood conflict, in which disagreement arises concerning resource division between current and future offspring, since investment in current offspring should reduce the amount of resources available for future offspring[1,4,7]
Single females showed a lower probability for laying a second egg clutch than females caring with a male partner (Table 1; Fig. 1B)

Summary

Introduction

Conflicts over parental investment are predicted to be common among family members, especially between parents and their offspring. Our results further show that paired females laid a second egg clutch more often and produced more offspring than single females, suggesting that the presence of a male partner shifts the conflict outcome towards the parental optimum This latter result is a novel aspect of parent–offspring theory, and represents an additional factor that might explain the evolution of biparental care. In a variety of mammals, the continued suckling of young causes a temporary infertility in m others[15,16,17], and in honey bees, larval begging pheromones have been shown to positively affect food provisioning, and to inhibit egg development in nursing w orkers[18,19] These examples illustrate that offspring might have the potential to affect the trade-off between investment in current offspring and the parent’s expectation of future offspring, it is currently unclear whether they are able to bias the conflict outcome toward their own optimum. In the presence of a helping male, females might reduce their amount of contacts with offspring, resulting in less offspring control over maternal physiology and reproductive behavior

Methods

Results

Conclusion