Data from: Differential allocation revisited: when should mate quality affect parental investment?

Differential allocation (DA) is the adaptive adjustment of reproductive investment (up or down) according to partner quality. A lack of theoretical treatments has led to some confusion in the interpretation of DA in the empirical literature. We present a formal framework for DA that highlights the nature of reproductive benefits versus costs for females mated to males of different quality. Contrary to popular belief, analytical and stochastic dynamic models both show that additive benefits of male quality on offspring fitness have no effect on optimal levels of female investment and thus cannot produce DA. Instead, if offspring fitness is affected multiplicatively by male quality, or male quality affects the female cost function, DA is expected because of changes in the marginal benefits or costs of extra investment. Additive male quality effects on the female cost function can cause a novel form of weak DA, because reduced costs can slightly favor current over future reproduction. Combinations of these distinct effects in more realistic model scenarios can explain various patterns of positive and negative DA reported for different species and mating systems. Our model therefore sheds new light on the diversity of empirical results by providing a strong conceptual framework for the differential allocation hypothesis.

差异化分配（Differential Allocation, DA）指依据交配伴侣的品质，对繁殖投入进行适应性增减的行为。当前相关理论研究的缺失，导致实证文献中对DA的解读存在一定混淆。本研究构建了一套针对DA的正式理论框架，着重剖析了与不同品质雄性交配的雌性个体，其繁殖收益与繁殖成本之间的本质关系。与学界主流认知相悖的是，解析模型与随机动态模型均证实，雄性品质对后代适合度的加性收益，并不会影响雌性繁殖投入的最优水平，因此无法催生DA。与之相反，若后代适合度受雄性品质的乘性调控，或是雄性品质会作用于雌性的成本函数，则会出现DA——这是因为额外繁殖投入的边际收益或成本发生了改变。雄性品质对雌性成本函数的加性效应，还可催生一种全新的弱DA形式：由于繁殖成本降低，雌性会略微倾向于当前繁殖而非未来繁殖。在更贴合自然实际的模型场景中，这些不同效应的组合，可以解释不同物种与交配系统中所观测到的各类正向与负向DA模式。本研究为差异化分配假说构建了坚实的概念框架，从而为实证研究结果的多样性提供了全新的解读视角。