School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, Washington, 98195, USA.
National Center for Ecological Analysis and Synthesis, University of California, Santa Barbara, 735 State St. #300, Santa Barbara, California, 93101, USA.
Ecology. 2017 Oct;98(10):2673-2683. doi: 10.1002/ecy.1961.
Population endangerment typically arises from multiple, potentially interacting anthropogenic stressors. Extensive research has investigated the consequences of multiple stressors on organisms, frequently focusing on individual life stages. Less is known about population-level consequences of exposure to multiple stressors, especially when exposure varies through life. We provide the first theoretical basis for identifying species at risk of magnified effects from multiple stressors across life history. By applying a population modeling framework, we reveal conditions under which population responses from stressors applied to distinct life stages are either magnified (synergistic) or mitigated. We find that magnification or mitigation critically depends on the shape of density dependence, but not the life stage in which it occurs. Stressors are always magnified when density dependence is linear or concave, and magnified or mitigated when it is convex. Using Bayesian numerical methods, we estimated the shape of density dependence for eight species across diverse taxa, finding support for all three shapes.
人口濒危通常是由多种潜在相互作用的人为压力源引起的。大量研究调查了多种压力源对生物的影响，通常侧重于单个生命阶段。对于暴露于多种压力源对种群水平的影响知之甚少，尤其是当暴露随时间变化时。我们为识别一生中受到多种压力源影响的物种提供了第一个理论基础，这些物种的影响可能会放大。通过应用种群建模框架，我们揭示了在不同生命阶段施加的压力源对种群反应产生放大（协同）或缓解（拮抗）的条件。我们发现，放大或缓解的关键取决于密度制约的形状，但不取决于其发生的生命阶段。当密度制约呈线性或凹性时，压力源总是会被放大，而当密度制约呈凸性时，压力源会被放大或缓解。我们使用贝叶斯数值方法，对来自不同分类群的八个物种的密度制约形状进行了估计，发现所有三种形状都得到了支持。
