Dispersal alters bacterial diversity and composition in a natural community

Abstract

Dispersal is central to the evolution and maintenance of microbial diversity. Quantifying microbial dispersal and its role in shaping communities remains a challenge, however. Here, we manipulated a bacterial community's dispersal rate in a grassland ecosystem and test whether this altered diversity and composition. We constructed bags of two nylon mesh sizes that allowed more or less bacterial movement and filled them with an edible or inedible substrate, irradiated plant litter or nylon sheets. We measured changes in bacterial abundance (using flow cytometry) and composition (using 16S amplicon sequencing) in the bags weekly over 5 months. The dispersal treatment altered bacterial colonization rates and led to differences in the abundance, richness, evenness and composition of communities. Overall, the study demonstrates that dispersal influences the assembly of this natural bacterial community.

Figure 1

Effects of dispersal limitation on bacterial (a) abundance, (b) composition, as assayed by 16S sequencing, (c) richness and (d) evenness, after rarefaction to standardize for sequencing effort among samples. Error bars in a are 1+1 s.e. The four treatment types included litter-containing open bags (purple), litter-containing closed bags (orange), nylon-containing open bags (light blue), nylon-containing closed bags (dark blue). Plant litter samples from the surrounding environment (green) were also collected for comparison.

Figure 2

Relative abundance of bacterial families found in each treatment type (litter-containing open bags, litter-containing closed bags and nylon-containing open bags) and the surrounding plant litter (environment), averaged across each time point.