Bradley Devon J, Gilbert Gregory S, Martiny Jennifer B H
Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman Street, Box G-W, Providence, RI 02912, USA.
Ecol Lett. 2008 May;11(5):461-9. doi: 10.1111/j.1461-0248.2008.01162.x. Epub 2008 Feb 25.
Pathogens are thought to promote diversity in plant communities by preventing competitive exclusion. Previous studies have focussed primarily on single-plant, single-pathogen interactions, yet the interactions between multiple pathogens and multiple hosts may have non-additive impacts on plant community composition. Here, we report that both a bacterial and a fungal pathogen maintained the diversity of a four-species plant community across five generations; however, significant interactions between the pathogens resulted in less plant diversity when the two pathogens were present than when the fungal pathogen was present alone. Standard models predict that pathogens will maintain plant diversity when they cause a disproportionate loss of fitness in the dominant plant species. In our experiment, however, pathogens maintained plant diversity because the rare species produced more seeds through a compensatory response to pathogen infection. Finally, we found that the influence of pathogens on maintaining plant diversity was 5.5 times greater than the influence of nutrient resource heterogeneity. Pathogens may be a major factor in maintaining plant diversity, and our findings emphasize the importance of investigating the roles of pathogens in natural plant communities.
病原体被认为通过防止竞争排斥来促进植物群落的多样性。以往的研究主要集中在单一植物与单一病原体的相互作用上，然而多种病原体与多种宿主之间的相互作用可能会对植物群落组成产生非加性影响。在此，我们报告一种细菌病原体和一种真菌病原体在五代时间里都维持了一个四种植物群落的多样性；然而，病原体之间的显著相互作用导致两种病原体同时存在时的植物多样性低于单独存在真菌病原体时。标准模型预测，当病原体导致优势植物物种的适合度不成比例地下降时，它们将维持植物多样性。然而，在我们的实验中，病原体维持了植物多样性，因为稀有物种通过对病原体感染的补偿反应产生了更多种子。最后，我们发现病原体对维持植物多样性的影响比营养资源异质性的影响大5.5倍。病原体可能是维持植物多样性的一个主要因素，我们的研究结果强调了研究病原体在天然植物群落中作用的重要性。
