The iters option appears twice in the wiki. https://mothur.org/wiki/Unifrac.unweighted In the first appearance it says that it is the number of tree randomizations in the second case it is the times the sequences are subsampled. What is it now.
The iters parameter is used in two places in the unifrac.unweighted command. When you use the subsample parameter, it determines the number of subsampled trees to create. When finding the pvalues, it is used to determine the number of randomizations to complete.