Figure 1. Mean (± SE) residual brain mass of amphibian and reptile species that were successful (open circles) and unsuccessful (dark squares) in establishing populations outside of their native geographic ranges in seven different biogeographic realms.

AA  =  Australasia, AT  =  Afrotropics, NT  =  Neotropics, NA  =  Nearctic, PA  =  Palearctic, OC  =  Oceania, and IM  =  Indomalaysia. Lack of standard errors in the AT and IM realms reflect low numbers of unsuccessful introductions.