Data from: Ontogenetic timing as a condition-dependent life history trait: high-condition males develop quickly, peak early and age fast

Within-population variation in ageing remains poorly understood. In males, condition-dependent investment in secondary sexual traits may incur costs which limit ability to invest in somatic maintenance. Moreover, males often express morphological and behavioural secondary sexual traits simultaneously, but the relative effects on ageing of investment in these traits remain unclear. We investigated the condition-dependence of male life history in the neriid fly Telostylinus angusticollis. Using a fully factorial design, we manipulated male early-life condition by varying nutrient content of the larval diet and, subsequently, manipulated opportunity for adult males to interact with rival males. We found that high-condition males developed more quickly and reached their reproductive peak earlier in life, but also experienced faster reproductive ageing and died sooner than low-condition males. By contrast, interactions with rival males reduced male lifespan but did not affect male reproductive ageing. High condition in early life is therefore associated with rapid ageing in T. angusticollis males, even in the absence of damaging male-male interactions. Our results show that abundant resources during the juvenile phase are used to expedite growth and development and enhance early-life reproductive performance at the expense of late-life performance and survival, demonstrating a clear link between male condition and ageing.

种群内部的衰老变异迄今仍未得到充分阐释。对于雄性而言，对第二性征（secondary sexual traits）的状态依赖性投入可能会产生适应性代价，进而限制其体细胞维持（somatic maintenance）的投入能力。此外，雄性往往同时表达形态学与行为学层面的第二性征，但这类特征的投入对衰老的相对影响仍不明确。我们以水蝇科（Neriidae）的窄角狭颊蝇（Telostylinus angusticollis）为研究对象，探究了雄性生活史的状态依赖性特征。本研究采用完全析因设计（fully factorial design），通过改变幼虫饲料的营养含量来调控雄性的早期发育状态，随后进一步调控成年雄性与同性竞争者互动的机会。研究结果显示，状态较佳的雄性发育速度更快，生命早期的繁殖峰值出现更早，但同时其生殖衰老速度更快，寿命也较状态较差的雄性更短。与之形成对比的是，与同性竞争者的互动仅缩短了雄性的寿命，并未对其生殖衰老产生影响。因此，即便不存在具有破坏性的雄性间互动，窄角狭颊蝇（Telostylinus angusticollis）雄性的早期良好状态仍与快速衰老相关。本研究结果表明，幼年阶段获取的充足资源会被用于加速生长发育、提升早期繁殖表现，但却以后期的生理机能与存活率为代价，清晰地揭示了雄性状态与衰老之间的直接关联。