<b>The evolution of negotiation strategies diversifies parental cooperation</b>

Parental cooperation is not self-evident, as conflicts often arise over individual contributions. Evolutionary game theory suggests this conflict may be resolved through negotiation, where parents adjust their care level based on their partner’s contribution. However, mathematical negotiation models typically predict low parental cooperation. As these models are not dynamically explicit and mostly neglect stochasticity, we employ individual-based simulations to investigate how parental negotiation strategies evolve and shape care patterns. Our results differ markedly from earlier analytical predictions. Parental negotiation strategies readily evolve, producing four alternative care patterns: uniparental care, sex-biased care and two types of egalitarian biparental care, that occasionally emerge as transitional stages over evolutionary time. We found that effective cooperation evolved regularly but, contrary to common expectations, always relied on a Tit-for-Tat strategy rather than parental compensation. Our study underscores that diverse cooperative patterns in animals can emerge from sex-specific negotiation strategies, even in the absence of initial sex roles and environmental variation.<br><br>All code scripts, simulation data and analysis scripts are included in this dataset亲本合作并非理所当然，个体间常因贡献分配产生冲突。进化博弈论（Evolutionary Game Theory）指出，这类冲突可通过协商解决：亲本可根据伴侣的贡献调整自身的抚育投入水平。然而，现有数学协商模型通常预测亲本合作水平较低。由于此类模型未具备动态显式性，且大多忽略了随机过程，因此本研究采用基于个体的模拟方法，探究亲本协商策略的演化路径及其对抚育模式的塑造作用。本研究所得结果与此前的分析预测存在显著差异。亲本协商策略可快速演化，形成四种不同的抚育模式：单亲抚育（uniparental care）、性别偏向型抚育（sex-biased care）以及两种平等式双亲抚育（egalitarian biparental care），这些模式在演化过程中偶尔会作为过渡阶段出现。研究发现，高效合作会规律性地演化产生，但与普遍预期相悖的是，此类合作始终依赖一报还一报策略（Tit-for-Tat），而非亲本补偿机制。本研究表明，即便不存在初始性别角色分化与环境变异，动物界多样的合作模式亦可通过性别特异性的协商策略演化产生。 本数据集包含所有代码脚本、模拟数据与分析脚本。