Positive relationship between environmental dissimilarity and spatial distance agrees with the predictions for an assemblage structure controlled by dispersal dynamics (Brown and Swan 2010). Dots are environmental dissimilarity and spatial distance between pairs of 16 reaches in an elevational gradient from 156 to 2720 m asl in northern Central America. Black solid lines are the mean fit Bayesian linear model between variables with Normal distribution. Blue faded lines are a 1000 possible lines from the Bayesian posterior distribution of the fitted model.