General patterns
Most of the studies assessing the dispersal-range size relationship have focused on marine and terrestrial systems (48 and 31 studies, respectively), whereas freshwater systems have received much less attention (only 7 studies; Fig. 1,2). Regarding taxa, most of studies have focused on vascular plants, fishes, and insects (24, 17 and 14 studies respectively; Fig. 1), whereas dispersal-range size relationships in bryophytes (liverworts), diatoms, trematodes and mycorrhiza fungal (all with a single study) have barely been studied. The majority of studied relationships (55%) showed a neutral effect of dispersal on range size, 40% of relationships were positive and only few (5%) were negative (Fig. 2). While for most of the taxa we did not find a consistent positive association between range size and dispersal, for molluscs, amphibians and birds we found more often positive effects of dispersal on range size than neutral effects (Fig. 1). Marine, terrestrial and freshwater realms showed similar proportions of positive and neutral relationships (Chi-squared test = 0.078, p = 0.67, Fig. 1). Interestingly, plants showed a lower proportion of positive relationships than animals (Chi-squared test = 10.72, p = 0.001, Fig. 1).