Contribution of dispersal syndromes to beta diversity
The effect of dispersal syndromes on beta diversity was estimated at all scales. For a given dispersal syndrome, we calculated the multiple site βSIM values excluding those species that displayed that specific dispersal syndrome, and calculated the delta (Δ) as the difference between the multiple site βSIM of the whole community and the multiple site βSIM of the same community without the species bearing that dispersal syndrome (delta ranges from -1 to 1). Therefore, a negative Δ indicates that a specific dispersal syndrome contributes to homogenize the community, whereas a positive Δ shows an increase of the heterogeneity in the community. To test if the Δ value was higher or lower than expected by chance, we generated 1000 random values of Δ between the multiple site βSIM of the whole community and 1000 values of random multiple site βSIM created by removing randomly the same number of species bearing that specific dispersal syndrome. This null distribution of Δ was used to test whether the observed the Δ was lower or higher than expected using a two-tailed test.