|Vander Wall, Stephen - UNIV OF NEVADA, RENO|
Submitted to: Seed Fate: Predations, Secondary . . . Seedling Establishment
Publication Type: Book / Chapter
Publication Acceptance Date: July 20, 2004
Publication Date: January 10, 2005
Citation: VanderWall, S.B., Longland, W.S. 2005. Diplochory and the evolution of seed dispersal. In: Forget, P.M., Lambert, J.E., Hulme, P.E., VanderWall, S.B. editors. Seed Fate: Predations, Dispersal, and Seedling Establishment. Wallingford, UK: CABI Publishing. p. 297-314. Interpretive Summary: "Seed dispersal" refers to any active movement (via wind, water, or animals) of seeds away from the plant that produced the seeds. We summarized published cases where seeds are dispersed in two distinctly different steps, and we describe five examples of such two-phase dispersal or "diplochory". Many potential advantages of seed dispersal have been proposed. Considering the five examples of diplochory discussed here, the first and second phases of seed dispersal seem to offer different advantages, and this may explain why diplochory has evolved repeatedly among different plants. The main advantage to the first phase of dispersal is to move seeds away from where they were produced, where seedlings have a better chance of surviving than they do beneath their parent plant. The main advantage to the second phase of dispersal is to move seeds to hidden sites, where they have less chance of being discovered and eaten by other seed-eaters than if they remained on the ground surface.
Technical Abstract: Seeds often arrive at a suitable site for germination via two or more distinct means of dispersal. We define primary dispersal as the initial movement of a seed away from the parent plant and secondary dispersal as subsequent movements of that seed by a distinctly different mechanism. For example, wind dispersal coupled with scatter hoarding, ballistic dispersal coupled with ant dispersal, or herbivory coupled with dung beetles. We survey these complex seed dispersal systems to determine what if any advantages they provide to plants. We examine the benefits of secondary dispersal that are not provided by primary dispersal, and we assess the costs of secondary dispersal in the form of increased seed mortality. We examine how seeds are adapted to these two distinct modes of dispersal and how adaptations for each mode of dispersal might interfere with each other. We examine how complex seed dispersal systems evolve and the role that mutualistic plant-animal interactions play in these processes. Finally, we identify areas of future research that will help answer questions concerning how complex seed dispersal systems function.