EFECTS OF SED DISPERSER SOCIAL BEHAVIOR ON PATTERNS OF SED MOVEMENT AND DEPOSITION

Abstract

Seed dispersal is critical to the maintenance of healthy terrestrial habitats and to the regeneration of degraded habitats. As anthropogenic deforestation, fragmentation, and defaunation continue, animal-mediated seed dispersal mutualisms are likely to be disrupted, with potentially serious consequences for forest dynamics. In this review, we examine the degree to which disperser sociality may influence seed dispersal outcomes. Available data are sparse and suggest that the relationship is complex, but some basic trends do emerge from the work to date. Degree of sociality, or group size, may increase the distance seeds are dispersed but also can lead to increased clumped distributions. Territoriality and the resulting defense of resources are likely to reduce the scale of dispersal and lead to clumped seed distributions. Nesting and mating behaviors such as male display are also likely to lead to more clumped distributions. Clumped deposition can have either positive or negative impacts on seed fate, depending on microsite quality, which can vary greatly. In all cases, however, there are exceptions and caveats and the one clear finding from this review is that more work is needed on this subject. We suggest that comparative studies which assess seed dispersal services offered by closely related, syntopic species that vary in key behavioral parameters will be most enlightening. We also highlight the recent use of molecular markers as a particularly effective tool to infer the dispersal services of given species, and to assess the consequences for genetic structure of the plants they disperse.