Problems with Dispersal Hypotheses:
Each group of species is has unique dispersal abilities and each dispersal event can be hypothesized to be unique, so is impossible to draw generalizations about biotic history using this theory.
Is not falsifiable. Can use dispersal to explain any possible distribution. Cannot show that dispersal did not occur.
Heavy reliance on fossils to determine centers of origin, but fossils do not demonstrate either age or complete distribution of a species.