Dormancy dampens the microbial distance-decay relationship

Abstract

Much of Earths biodiversity has the capacity to engage in dormancy whereby individuals enter a reversible state of reduced metabolic activity. By increasing resilience to unfavorable conditions, dormancy leads to the accumulation of \"seed banks\" that should diminish the influence of environmental filtering, while allowing passive dispersers to colonize new habitats. Although prevalent among single-celled organisms, evidence that dormancy influences patterns of microbial biodiversity and biogeography is lacking. We constructed geographical and environmental distance-decay relationships (DDRs) using 16S rRNA sequencing to characterize the total (DNA) and the active (RNA) bacterial communities in a regional survey of 49 forested ponds. As expected, the total community harbored greater diversity and exhibited weaker DDRs than the active portion of the community. These empirical observations were robust to different measures of community similarity and random resampling tests. Furthermore, findings from the field survey were reproduced by models that included aspects of dormancy along with the geographical coordinates and environmental characteristics of our study system. In addition to maintaining local diversity, our results support recent theoretical predictions that dormancy shapes geographical patterns of biodiversity.