Geographic Ranges of Plant Species in Relation to Dispersal Morphology, Growth Form and Diaspore Weight

Abstract

We investigated the relationship of geographic range to growth form, dispersal morphology and diaspore weight within three comparative databases of 219-325 native species from arid central Australia, semi-arid western NSW and maritime Sydney. Geographic range was measured as the number of regions occupied. In the arid and semi-arid floras, but not in the maritime flora, species adapted for dispersal by vertebrates (mainly birds) tended to occupy more regions than species adapted for dispersal by other means. The same pattern occurred within four major families (Chenopodiaceae, Myoporaceae, Mimosaceae and Solanaceae), and thus was not a product of differences between families. We suggest that lineages with adaptations for long-range dispersal may have undergone a lesser incidence of geographic speciation, within the arid and semi-arid flora.