Loss of biodiversity is a major threat to the ecosystem processes upon which society depends.Natural ecosystems differ in their resistance to invasion by alien species,and this resistance can depend on the diversity in the system.Little is known,however,about the barriers that microbial diversity provides against microbial invasion.The increasing prevalence of antibioticresistant bacteria is a serious threat to public health in the 21st century.We explored the consequences of the reduction in soil microbial diversity for the dissemination of antibiotic resistance.The relationship between this diversity and the invasion of antibiotic resistance was investigated using a dilution-to-extinction approach coupled with high-capacity quantitative PCR.Microbial diversity was negatively correlated with the abundance of antibiotic-resistance genes,and this correlation was maintained after accounting for other potential drivers such as incubation time and microbial abundance.Our results demonstrate that high microbial diversity can act as a biological barrier resist the spread of antibiotic resistance.These results fill a critical gap in our understanding of the role of soil microbial diversity in the health of ecosystems.
