Randomizes a binary matrix speciesData by reshuffling elements
within each column. Sampling weights for each row are proportional to
row sums. Makes a call to the vector_sample function.
Returns a binary presence-absence matrix with the same
dimensions and colsums as the input matrix.
Details
This algorithm preserves differences among sites in species
richness, but assumes differences among species in commonness and rarity
are proportional to observed species occurrences (= row sums).
References
Gotelli, N.J. 2000. Null model analysis of species co-occurrence
patterns. Ecology 81: 2606-2621.