Data from: Delayed dispersal and the cost and benefits of different routes to independent breeding in a cooperative breeding bird

Why sexually mature individuals stay in groups as non-reproductive subordinates is central to the evolution of sociality and cooperative breeding. To understand such delayed dispersal, its costs and benefits need to be compared with those of permanently leaving to float through the population. However, comprehensive comparisons, especially regarding differences in future breeding opportunities, are rare. Moreover, extra-territorial prospecting by philopatric individuals has generally been ignored, even though the factors underlying this route to independent breeding may differ from those of strict philopatry or floating. We use a comprehensive predictive framework to explore how various costs, benefits and intrinsic, environmental and social factors explain philopatry, prospecting and floating in Seychelles warblers (Acrocephalus sechellensis). Floaters more likely obtained an independent breeding position before the next season than strictly philopatric individuals, but also suffered higher mortality. Prospecting yielded similar benefits to floating but lower mortality costs, suggesting that it is overall more beneficial than floating and strict philopatry. Whereas prospecting is probably individual-driven, though limited by resource availability, floating likely results from eviction by unrelated breeders. Such differences in proximate and ultimate factors underlying each route to independent breeding highlight the need for simultaneous consideration when studying the evolution of delayed dispersal.性成熟个体以非繁殖从属个体的身份留在种群中，这一问题是社会性演化与合作繁殖（cooperative breeding）研究的核心议题。为阐明此类延迟扩散（delayed dispersal）现象，需将其对应的成本与收益，与永久脱离种群进行漫游的个体的成本收益进行对比。然而，现有研究极少开展全面对比，尤其是针对未来繁殖机会差异的相关分析。此外，恋巢性个体的领地外探查行为（extra-territorial prospecting）长期被忽视，尽管该路径实现独立繁殖的驱动因素，或与严格恋巢或漫游个体的驱动因素存在显著差异。本研究构建了一套全面的预测框架，用以剖析各类成本、收益以及内在、环境与社会因素，如何解释塞舌尔莺（Acrocephalus sechellensis）的恋巢、领地探查与漫游行为。研究结果表明，漫游个体较严格恋巢个体，更易在下一个繁殖季来临前获得独立繁殖领地，但同时需承担更高的死亡风险。领地探查行为所能带来的收益与漫游相近，但死亡成本更低，这意味着该策略的整体效益优于漫游与严格恋巢策略。尽管领地探查大概率由个体自身驱动，但受资源可获得性的限制；而漫游行为则可能源于非亲属繁殖者的驱逐。每种独立繁殖路径背后的近因与终极因素（proximate and ultimate factors）存在上述差异，这凸显了在探究延迟扩散的演化机制时，需同时考量各类繁殖路径的必要性。