Life-history theory predicts that animals should develop adaptive trade-offs between survival and reproduction to maximize their fitness. This results in a continuum of life-history strategies among species, ranging from slow to fast paces-of-life. The optimal pace-of-life has been shown to vary within environmental gradients, with a commonly observed pattern of a slow-to-fast continuum from the tropics to the poles. Within species, pace-of-life variability has however received much less attention. In this study, we investigated whether or not the pace-of-life of populations within a species follows the expected slow–fast continuum associated with latitude. We analysed the variability of life-history strategies among populations of the European roller Coracias garrulus, a long-distance migratory species, comparing breeding parameters and adult survival between populations across a latitudinal gradient. The findings showed a negative correlation between survival and clutch size in roller populations, with a slower pace-of-life in the northern populations and a faster pace-of-life in the southern populations: a reverse gradient to what might be expected from inter-specific studies. These results suggest that northern populations would benefit from measures enhancing adult survival probability, such as reduction in harvesting rates, while southern populations would respond better to actions favouring reproductive success, such as nesting site provisioning. This study highlights that life-history traits can vary substantially between populations of a single species with a large latitudinal breeding range, and pinpoint how knowledge about this variability may be key in anticipating different populations’ responses to threats as well as to conservation strategies.

生活史理论预测，动物应该在生存和繁殖之间进行适应性权衡，以最大限度地提高它们的适应性。这导致了物种之间的生活史策略的连续统一体，从缓慢到快速的生活节奏。最佳生活节奏已被证明随环境梯度而变化，通常观察到从热带到极地的由慢到快的连续体模式。然而，在物种内，生活节奏的变异性受到的关注要少得多。在这项研究中，我们调查了一个物种内种群的生活节奏是否遵循与纬度相关的预期的慢-快连续体。我们分析了欧洲滚轴Coracias garrulus种群生活史策略的变异性，一种长距离迁徙物种，比较跨越纬度梯度的种群之间的繁殖参数和成虫存活率。研究结果表明，滚子种群的存活率和离合器大小之间呈负相关，北方种群的生活节奏较慢，南方种群的生活节奏较快：与国际间预期的相反梯度- 具体研究。这些结果表明，北方种群将受益于提高成虫存活概率的措施，例如降低收获率，而南方种群将对有利于繁殖成功的行动做出更好的反应，例如提供筑巢地点。这项研究强调，具有较大纬度繁殖范围的单个物种的种群之间的生活史特征可能会有很大差异，