Data_Sheet_1_Being the Winner Is Being the Loser When Playing a Parental Tug-of-War – A New Framework on Stability of Biparental Care.docx

Because there are basic sexual differences in reproductive potential, and the cost of parental care is assumed to be high, biparental care is viewed as a constant tug-of-war between the partners. This raises the question of the system’s evolutionary stability. Several models have been proposed to resolve this problem but none has received unequivocal support. Here, I propose a framework that not only integrates the earlier theoretical ideas (sealed bids, negotiation) but also considers the importance of the environment (frequently neglected in previous models) and views the cost of parental care from a different perspective (costly in terms of parent’s survival only when performed close to the boundary of parental capacity). The framework suggests that sexual conflict may not be such a significant factor mediating parental care as commonly assumed, and that a parent trying to shift the parental burden onto the partner – assumed to be the winner in the tug-of-war interplay – is actually more likely to be a loser, as doing so may put the success of the current breeding attempt in jeopardy, thereby reducing overall fitness of the parent. Once it is realized that the importance of sexual conflict is actually much less than it seems, it becomes clear that the stability of the biparental care system no longer seems to be such a puzzling issue.

鉴于繁殖潜能中存在基本的性别差异，且假定亲代抚育成本高昂，双亲抚育被视为伴侣之间持续的拉锯战。这引发了系统进化稳定性的疑问。已有数种模型被提出以解决这一问题，但均未获得明确的支持。在此，我提出一个框架，该框架不仅整合了早期的理论思想（密封报价、协商），还考虑了环境的重要性（在先前模型中常被忽视），并从不同角度审视亲代抚育的成本（仅在接近亲代能力边界时进行，对父母的生存而言成本高昂）。该框架提出，性冲突可能并非如人们通常所认为的那样，是调节亲代抚育的关键因素，而试图将抚育负担转移至伴侣——假设在拉锯战中为胜者——的父母实际上更有可能成为输家，因为这样做可能会危及当前繁殖尝试的成功，从而降低父母的整体适应性。一旦认识到性冲突的重要性实际上远小于表面看来，双亲抚育系统的稳定性便不再是一个令人困惑的问题。