The dataset is ecological (species abundance), where I am calculating distances between 51 sampling sites, based on abundances of 3200 species. The species abundance values go up to 2700, and the rest of the abundance matrix is pretty sparse with many zeros.
I am calculating distance matrices using the vegan package in R, like this:
dist.jac <- vegan::distance(abund, method="jaccard") dist.bray <- vegan::distance(abund, method="bray")
Mantel test says they are nearly the same.
Moreover, once ordinated using NMDS, the Procrustes test reports absolute identity (t=1, p<0.0001).
Does that say anything about my data structure? Should I be concerned?