Department of Zoology, University of Oxford, Oxford, OX1 3PS, UK.
Department of Coastal Systems, NIOZ Royal Netherlands Institute for Sea Research, Utrecht University, P.O. Box 59, 1790 AB, Den Burg, Texel, the Netherlands.
Ecol Lett. 2020 May;23(5):811-820. doi: 10.1111/ele.13470. Epub 2020 Feb 23.
Fluctuating population density in stochastic environments can contribute to maintain life-history variation within populations via density-dependent selection. We used individual-based data from a population of Soay sheep to examine variation in life-history strategies at high and low population density. We incorporated life-history trade-offs among survival, reproduction and body mass growth into structured population models and found support for the prediction that different life-history strategies are optimal at low and high population densities. Shorter generation times and lower asymptotic body mass were selected for in high-density environments even though heavier individuals had higher probabilities to survive and reproduce. In contrast, greater asymptotic body mass and longer generation times were optimal at low population density. If populations fluctuate between high density when resources are scarce, and low densities when they are abundant, the variation in density will generate fluctuating selection for different life-history strategies, that could act to maintain life-history variation.
在随机环境中，种群密度的波动可能通过密度依赖选择来维持种群内的生活史变异。我们使用来自一个斯澳绵羊种群的个体数据，在高和低种群密度下研究了生活史策略的变化。我们将生存、繁殖和体重增长之间的生活史权衡纳入到结构化的种群模型中，并发现支持这样的预测，即在低密度和高密度下，不同的生活史策略是最优的。即使体重较重的个体有更高的生存和繁殖概率，在高密度环境中也会选择较短的世代时间和较低的渐近体重。相比之下，在低密度时，更大的渐近体重和更长的世代时间是最优的。如果种群在资源稀缺时波动到高密度，而在资源丰富时波动到低密度，那么密度的变化将产生对不同生活史策略的波动选择，这可能有助于维持生活史的变异。
