Life-history strategies differ with respect to investment in current versus ‘future’ reproduction, but when is this future? Under the novel ‘temporality in reproductive investment hypothesis’, we postulate variation should exist in the time frame over which reproductive costs are paid. Slow-paced individuals should pay reproductive costs over short (e.g. inter-annual) time scales to prevent reproductive costs accumulating, whereas fast-paced individuals should allow costs to accumulate (i.e. senescence). Using Fourier transforms, we quantify adjustments in clutch size with age, across four populations of blue tits (Cyanistes caeruleus). Fast populations had more prevalent and stronger long-term changes in reproductive investment, whereas slower populations had more prevalent short-term adjustments. Inter-annual environmental variation partly accounted for short-, but not long-term changes in reproductive investment. Our study reveals individuals differ in when they pay the cost of reproduction and that failure to partition this variation across different temporal scales and environments could underestimate reproductive trade-offs.

中文翻译：

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雀形目慢快连续体中繁殖投资的时间尺度差异

生活史策略在对当前和“未来”繁殖的投资方面有所不同，但未来是什么时候？根据新的“生殖投资的时间性假说”，我们假设在支付生殖成本的时间范围内应该存在差异。慢节奏的个体应该在短时间内（例如跨年）支付生殖成本，以防止生殖成本累积，而快节奏的个体应该允许成本累积（例如衰老）。使用傅立叶变换，我们量化了四个蓝山雀种群（ Cyanistes caeruleus）中离合器尺寸随年龄的变化。）。快速人口在生殖投资方面具有更普遍和更强的长期变化，而速度较慢的人口具有更普遍的短期调整。年际环境变化部分解释了生殖投资的短期变化，但不是长期变化。我们的研究表明，个体在支付繁殖成本时存在差异，并且未能在不同的时间尺度和环境中划分这种变化可能会低估繁殖权衡。