Stressors such as antibiotics, herbicides, and pollutants are becoming increasingly common in the environment. The effects of stressors on populations are typically studied in homogeneous, nonspatial settings. However, most populations in nature are spatially distributed over environmentally heterogeneous landscapes with spatially restricted dispersal. Little is known about the effects of stressors in these more realistic settings. Here, we combine laboratory experiments with novel mathematical theory to rigorously investigate how a stressor’s physiological effect and spatial distribution interact with dispersal to influence population dynamics. We prove mathematically that if a stressor increases the death rate and/or simultaneously decreases the population growth rate and yield, a homogeneous distribution of the stressor leads to a lower total population size than if the same amount of the stressor was heterogeneously distributed. We experimentally test this prediction on spatially distributed populations of budding yeast (Saccharomyces cerevisiae). We find that the antibiotic cycloheximide increases the yeast death rate but reduces the growth rate and yield. Consistent with our mathematical predictions, we observe that a homogeneous spatial distribution of cycloheximide minimizes the total equilibrium size of experimental metapopulations, with the magnitude of the effect depending predictably on the dispersal rate and the geographic pattern of antibiotic heterogeneity. Our study has implications for assessing the population risk posed by pollutants, antibiotics, and global change and for the rational design of strategies for employing toxins to control pathogens and pests.
Bibliographical noteFunding Information:
We thank A. Murray and M. Mueller for providing strains. The editors and two anonymous reviewers provided insightful comments on the manuscript. This work was supported by the University of California, Davis, Chancellor?s Postdoc Fellowship program (to B.Z.), the William H. Evoy Graduate Research and Savage Graduate Research Support Fund (to A.K.), and the National Science Foundation and the National Natural Science Foundation of China (to W.-M.N.). D.L.D. was supported by the Greater Everglades Priority Ecosystem Science program. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the US government.
- Consumer-resource model
- Laboratory experiments
- Movement ecology
- Patchy environment
- Spatial ecology
- Spatially heterogeneous parameters
PubMed: MeSH publication types
- Journal Article
- Research Support, Non-U.S. Gov't
- Research Support, U.S. Gov't, Non-P.H.S.