Individuals delay natal dispersal for many reasons. There may be no place to disperse to; immediate dispersal or reproduction may be too costly; immediate dispersal may mean that the individual and their relatives miss the benefits of group living. Understanding the factors that lead to the evolution of delayed dispersal is important because delayed dispersal sets the stage for complex social groups and social behavior. Here, we study the evolution of delayed dispersal when the quality of the local environment is improved by greater numbers of individuals (, safety in numbers). We assume that individuals who delay natal dispersal also expect to delay personal reproduction. In addition, we assume that improved environmental quality benefits manifest as changes to fecundity and survival. We are interested in how do the changes in these life-history features affect delayed dispersal. We use a model that ties evolution to population dynamics. We also aim to understand the relationship between levels of delayed dispersal and the probability of establishing as an independent breeder (a population-level feature) in response to changes in life-history details. Our model emphasizes kin selection and considers a sexual organism, which allows us to study parent–offspring conflict over delayed dispersal. At evolutionary equilibrium, fecundity and survival benefits of group size or quality promote higher levels of delayed dispersal over a larger set of life histories with one exception. The exception is for benefits of increased group size or quality reaped by the individuals who delay dispersal. There, the increased benefit does not change the life histories supporting delay dispersal. Next, in contrast to previous predictions, we find that a low probability of establishing in a new location is not always associated with a higher incidence of delayed dispersal. Finally, we find that increased personal benefits of delayed dispersal exacerbate the conflict between parents and their offspring. We discuss our findings in relation to previous theoretical and empirical work, especially work related to cooperative breeding.

中文翻译：

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具有群体规模效应和种群动态的延迟扩散的演化

个体延迟出生扩散有多种原因。可能无处可散；立即扩散或繁殖可能成本太高；立即分散可能意味着个人及其亲属无法享受集体生活的好处。了解导致延迟扩散演化的因素很重要，因为延迟扩散为复杂的社会群体和社会行为奠定了基础。在这里，我们研究当当地环境质量因更多个体（数量安全）而改善时延迟扩散的演变。我们假设延迟出生扩散的个体也期望延迟个人繁殖。此外，我们假设环境质量改善的效益表现为生育力和生存的变化。我们感兴趣的是这些生活史特征的变化如何影响延迟扩散。我们使用一个将进化与种群动态联系起来的模型。我们还旨在了解延迟扩散水平与响应生活史细节变化而成为独立繁殖者（种群水平特征）的概率之间的关系。我们的模型强调亲缘选择并考虑有性有机体，这使我们能够研究亲子因延迟扩散而发生的冲突。在进化平衡中，群体规模或质量的繁殖力和生存效益促进了更大范围的生活史中更高水平的延迟扩散，但有一个例外。例外情况是延迟分散的个人获得的群体规模或质量增加的好处。在那里，增加的益处不会改变支持延迟扩散的生活史。接下来，与之前的预测相反，我们发现在新地点建立的概率较低并不总是与延迟扩散的较高发生率相关。最后，我们发现延迟分散带来的个人利益的增加加剧了父母与其后代之间的冲突。我们讨论了与之前的理论和实证工作相关的发现，特别是与合作育种相关的工作。