0.4
(a)
ARCHAEA
p=0.002
M2=0.605
NMDS Axis 2
HR nodules
ERB nodules
HR sediments
ERB sediments
TRFLP
iTAG
3-6
12-15
0-3
9-12
6-9
0-3
-0.2
-0.8
0.4
NMDS Axis 1
0.3
(b)
BACTERIA
P<0.001
M2=0.293
HR nodules
ERB nodules
12-1
9-12
0-3
9-12
6-9
NMDS Axis 2
ERB sediments
TRFLP
iTAG
3-6
5
l
9-12, periphera
6-9
HR sediments
3-6
9-12, m
at
-0.25
-0.6
NMDS Axis 1
0.6
Supplementary Figure 1. Procrustes comparison of sample relationships between the iTAG and TRFLP datasets, for
(a) archaea and (b) bacteria. iTAG ordination coordinates (see Figure 2 in main text) were used as the reference, against
which TRFLP coordinates were transformed by translation, rotation, reflection, and/or scaling to minimize distance to
the iTAG datapoints. The purpose was to test the closeness of fit between the two sets of datapoints, and therefore infer
whether the biological similarity trends in iTAG and TRFLP data support one another. The analysis was completed
1,000 times and the resulting M2 and p-values are given on the plot. Lower M2 values indicate better closeness of fit
between the datasets, and range from a possible value of 0 to 1. Lower p-values indicate stronger statistical support as
determined through repeated iterations. Among the bacterial dataset, the p- and M2-values indicate decent closeness of
fit between the overall iTAG and TRFLP datasets. Among the archaeal dataset, the M2 value is not particularly good,
but NMDS biological patterns nonetheless appear to be largely maintained. As seen in the plots, some samples clearly
fit more closely than others (that is, two points connected by a shorter arrow). Arrows are meant to help the reader
connect iTAG and TRFLP ordination points from the same sample, to determine whether iTAG and TRFLP datasets
demonstrate similar biological similarity trends. Arrows always point from the TRFLP to the iTAG point, since TRFLP
coordinates were transformed to minimize distance to iTAG points. One archaeal sample (ERB clam core 0-3 cmbsf
nodule) was excluded from analysis because it was substantially different than all other samples and skewed the
ordination beyond possible interpretation.