between dispersal capacity and other important life-history stages.
Our first aim was to quantify the cross-species relationship between seed mass and dispersal distance. Seed mass influences many different life-history stages in plants. Small-seeded species have low rates of survival in the early stages of establishment (Moles & Westoby 2004). Small-seeded species also tend to have high annual seed output, but short lifespans (Moles & Westoby 2004; Moles et al. 2004). Relationships between seed mass and dispersal distances are less well understood than relationships between seed mass and other life-history stages. This is surprising, because seed mass is important for species’ lifehistory strategies, and dispersal is a major life-history stage. There is a perception that small-seeded species should disperse better than large-seeded species, trading off seed mass (maternal provisioning) with dispersal capacity (Venable & Brown 1988; Greene & Johnson 1993; Cornelissen et al. 2003). Small-seeded species may increase their probability of survival by dispersing further from the parent plant than do large-seeded species (Janzen 1970; Hyatt et al. 2003). High annual seed production of small-seeded species may enhance the likelihood of rare long-distance dispersal events, resulting in dispersal curves with fat, long tails and increased mean and maximum dispersal distances. We therefore predicted that small-seeded species would have greater dispersal distances than large-seeded species.