Fig. 2: Soil microbial community composition, diversity, and indicator species for the DO-18 kimberlite.

a Distribution of 16 S rRNA gene reads per phylum for each sample at the DO-18 kimberlite. The number of reads per phylum is calculated as a percentage of the total reads for each sample. b Box plots show the number of observed operational taxonomic units (OTUs; 97% sequence similarity) across background soils and soils above the DO-18 kimberlite (from data that has been rarefied to 16365 sequences per sample). Median values are indicated by the solid line within each box, and the box extends to upper and lower quartile values. Stars indicate the mean. Error bars represent standard deviation. c Hierarchical relationships amongst soil samples are based on Euclidean distance of 16S-OTU abundances. The hierarchical relationships between soil samples were obtained using the unweighted pair group method with arithmetic mean (UPGMA) clustering algorithm. Node labels identify different clusters (1–7) and the number inside the wedge indicates the number of soil samples in a cluster. Pie charts indicate the percentage of samples that are located above the kimberlite (blue segments) and percentage of samples that are located above background (beige segments) for each cluster. d Response ratios of geochemical pathfinder elements compared to suites of indicator species derived from microbial community fingerprinting at DO-18. Response ratios are expressed in percent (%) calculated by the average “on deposit” (soils above kimberlite) over the average “off deposit” (soils above background) relative to an equivalent ratio of 1. e A microbial anomaly map shows the normalized sum of incubation-predicted indicator species’ spatial distribution at DO-18. f A microbial anomaly map shows the normalized sum of incubation-predicted indicator species and DO-18 predicted indicator species’ spatial distribution at DO-18. Indicator species in (e, f) are based on a LEfSe indicator species analysis. g A geochemical anomaly map at DO-18 shows the normalized sum of pathfinder elements Cr, Mg, Nb, and Ni. Results are derived from 4-acid digests and ICP-MS determination of elements from b-horizon soils. In each map (e–g), data (multi-colored bubbles) overlies a surficial materials map derived from field observations. Individual indicator species (e, f) or pathfinder elements (g) were normalized to the mean prior to summation and anomaly intervals are based on probability plots, where the “*” represents soil samples that correspond spatially to “on deposit” (above kimberlite) (e–g).