Different calculation of Bray-Curtis dissimilarity in R and mothur? - (May/06/2015 )

I also posted this in BioStar (https://www.biostars.org/p/141082/).

 

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 (in the document of vegdist):

bray d = (sum abs(x-x))/(sum (x+x))   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!

Yes