When both selection and demography vary over time, how can the long-run expected strength of selection on quantitative traits be measured? There are two basic steps in the proposed new analysis: one relates trait values to fitness components, and the other relates fitness components to total fitness. We used one population projection matrix for each state of the environment together with a model of environmental dynamics, defining total fitness as the stochastic growth rate. We multiplied environment-specific, stage-specific mean-standardized selection gradients by environment-specific, stage-specific elasticities of the stochastic growth rate, summing over all relevant life-history and environmental paths. Our two example traits were floral tube length in a rainforest herb and the timing of birth in red deer. For each species, we constructed two models of environmental dynamics, including one based on historical climate records. We found that total integrated selection, as well as the relative contributions of life-history pathways and environments, varied with environmental dynamics. Temporal patterning in the environment has selective consequences. Linking models of environmental change to relevant short-term data on demography and selection may permit estimation of the force of selection over the long term in variable environments.

中文翻译：

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当人口统计学和选择梯度随时间变化时整合选择的新方法

When both selection and demography vary over time, how can the long-run expected strength of selection on quantitative traits be measured? 拟议的新分析有两个基本步骤：一个将特征值与​​适应度成分相关联，另一个将适应度成分与总适应度相关联。我们为环境的每种状态使用了一个人口预测矩阵以及环境动力学模型，将总适应度定义为随机增长率。我们将特定环境、特定阶段的均值标准化选择梯度乘以特定环境、特定阶段的随机增长率弹性，对所有相关的生活史和环境路径求和。我们的两个示例特征是热带雨林药草的花管长度和马鹿的出生时间。对于每个物种，我们构建了两种环境动态模型，其中一种基于历史气候记录。我们发现总的综合选择，以及生活史路径和环境的相对贡献，随着环境动态而变化。环境中的时间模式具有选择性的后果。将环境变化模型与有关人口统计学和选择的相关短期数据联系起来，可以估计可变环境中长期选择的力量。