Fig. 1. Overview of positive and non-positive relationships between dispersal-related traits and range size examined in this review. The number of positive and non-positive relationships is indicated for (a) each realm (terrestrial, marine, freshwater), (b) clade and specific taxonomic groups (animals, plants, fish, insects, crustaceans, birds, mammals, echinoderms, molluscs, amphibians, liverworts, reptiles) and (c) total. Mycorrhiza, trematodes, diatoms and invertebrates were not included here because they had less than four reported relationships (all non-positive).
There is also a clear spatial structure in study location (Fig. 2). For terrestrial systems, most of the studies have been performed in the palearctic region (23 studies), followed by studies including multiple regions (i.e., studies that include more than one region, including global studies) (15 studies), whereas much less attention has been given to neotropical and paleotropical regions (including the Madagascar region). For marine systems, 32% of the studies (10 studies) examined multiple regions, followed by studies in the Indo-Pacific and the Tropical Eastern Pacific (26%, 8 studies each), whereas the Atlantic and Mediterranean regions were much less studied (4 and 1 study respectively, Fig. 1). For freshwater systems, only 2 studies have been performed for multiple regions, the remaining 5 studies have only considered Nearctic a Palearctic regions (2 and 3 studies, respectively).