The Bray-Curtis dissimilarity using vegdist of the vegan package in R is calculated as the sum of absolute difference between each pair of OTU:

`bray`

d[jk] = (sum abs(x[ij]-x[ik]))/(sum (x[ij]+x[ik]))

binary: (A+B-2*J)/(A+B)

But this is different from what is described in mothur (http://www.mothur.org/wiki/Braycurtis), and wiki (http://en.wikipedia.org/wiki/Bray%E2%80%93Curtis_dissimilarity), which use the sum of minimum abundance of each pair of OTU.

Are they the same mathematically?

Thanks!