Data from: Morph-specific patterns of reproductive senescence: connections to discrete reproductive strategies

How reproductive strategies contribute to patterns of senescence in natural populations remains contentious. We studied reproductive senescence in the dimorphic white-throated sparrow, an excellent species for exploring this issue. Within both sexes the morphs use distinct reproductive strategies, and disassortative pairing by morph results in pair types with distinct parental systems. White morph birds are more colorful and aggressive than tan counterparts, and white males compete for extra-pair matings whereas tan males are more parental. Tan males and white females share parental care equally, whereas white males provide little parental support to tan females. We found morph-specific patterns of reproductive senescence in both sexes. White males exhibited greater reproductive senescence than tan males. This result likely reflects the difficulty of sustaining a highly competitive reproductive strategy as aging progresses, rather than high physiological costs of competitiveness, since white males were also long-lived. Moreover, morph was not consistently related to reproductive senescence across the sexes, arguing against especially high costs of the traits associated with white morph identity. Rather, tan females exhibited earlier reproductive senescence than white females, and were short-lived, perhaps reflecting the challenges of unsupported motherhood. Results underscore the importance of social dynamics in determining patterns of reproductive senescence.繁殖策略如何塑造自然种群的衰老模式，目前仍存在诸多争议。我们以二形性白喉带鹀（white-throated sparrow）为研究对象，探讨其生殖衰老模式，该物种是探索此类议题的理想实验模型。该物种雌雄两性的不同形态个体均采用截然不同的繁殖策略，且基于形态的异配配对会形成具有差异化双亲抚育体系的配偶对。白色形态个体的羽色更为鲜亮、攻击性强于棕褐色形态个体；白色形态雄性会通过竞争获取额外配对交配（extra-pair matings）机会，而棕褐色形态雄性则更专注于双亲抚育工作。棕褐色雄性与白色雌性会均等分担双亲抚育任务，而白色雄性几乎不会为棕褐色雌性提供抚育支持。我们发现，雌雄两性均存在形态特异性的生殖衰老模式。白色形态雄性的生殖衰老程度显著高于棕褐色雄性。该结果或反映出：随着年龄增长，维持高竞争性繁殖策略的难度不断提升，而非竞争性行为本身带来了高昂的生理代价——因为白色形态雄性的寿命本就更长。此外，在雌雄两性中，形态与生殖衰老的关联并不一致，这一结果驳斥了"与白色形态相关的性状存在极高代价"这一观点。与之相反，棕褐色雌性的生殖衰老启动早于白色雌性，且寿命更短，这或许反映了缺乏雄性抚育支持的母性所面临的生存与繁殖挑战。本研究结果凸显了社会动态在决定生殖衰老模式中的关键作用。