Data from: Ageing and senescence across reproductive traits and survival in superb fairy-wrens (Malurus cyaneus)

Why do senescence rates of fitness-related traits often vary dramatically?
By considering the full ageing trajectories of multiple traits we can
better understand how a species’ life-history shapes the evolution of
senescence within a population. Here, we examined age-related changes in
sex-specific survival, reproduction, and several components of
reproduction using a long-term study of a cooperatively-breeding songbird,
the superb fairy-wren (Malurus cyaneus). We compared ageing patterns
between traits by estimating standardized rates of maturation, the age of
onset of senescence, and rates of senescence, while controlling for
confounding factors reflecting individual variability in life-history. We
found striking differences in ageing and senescence patterns between
survival and reproduction, as well as between reproductive traits. In both
sexes, survival started to decline from maturity onwards. In contrast, all
reproductive traits showed improvements into early adulthood, and many
showed little or no evidence of senescence. In females, despite senescence
in clutch size, number of offspring surviving to independence did not
decline in late life, possibly due to improvements in maternal care with
age. Superb fairy-wrens have exceptionally high levels of extra-group
paternity, and male extra-group reproductive success showed much greater
changes with age than did within-group reproductive success, suggesting
that male reproductive ageing is driven by sexual selection. We discuss
how the superb fairy-wrens’ complex life history may contribute to the
disparate ageing patterns across different traits.

为何与适合度（fitness）相关的性状的衰老速率通常存在显著差异？通过考量多个性状的完整衰老轨迹，我们能够更深入地理解一个物种的生活史如何塑造种群内衰老的演化。本研究依托对合作繁殖鸣禽——华丽细尾鹩莺（Malurus cyaneus）的长期监测，分析了性特异性存活、繁殖以及多项繁殖组分随年龄的变化。我们通过估算标准化的成熟速率、衰老起始年龄以及衰老速率，同时控制反映个体生活史变异的混杂因素，对不同性状的衰老模式进行了比较。研究发现，存活与繁殖之间、以及不同繁殖性状之间的衰老模式存在显著差异。两性的存活均从成熟阶段起开始下降。与之相反，所有繁殖性状在成年早期均呈现提升趋势，且多数几乎未表现出衰老迹象。在雌性个体中，尽管窝卵数存在衰老现象，但子代至独立阶段的存活数量并未在晚年出现下降，这可能与雌性的母性照料随年龄提升有关。华丽细尾鹩莺拥有极高的群外父权比例，雄性的群外繁殖成功率随年龄的变化幅度远高于群内繁殖成功率，这表明雄性的生殖衰老由性选择驱动。我们还讨论了华丽细尾鹩莺复杂的生活史如何促成不同性状间迥异的衰老模式。