A strong conditional mutualism limits and enhances seed dispersal and germination of a tropical palm

Klinger, Rob and Rejmánek, Marcel (2010) A strong conditional mutualism limits and enhances seed dispersal and germination of a tropical palm. Oecologia, 162 (4). pp. 951-963. ISSN 0029-8549

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    Abstract

    Seed predation and seed dispersal can have strong eVects on early life history stages of plants. These processes have often been studied as individual eVects, but the degree to which their relative importance co-varies with seed predator abundance and how this inXuences seed germination rates is poorly understood. Therefore, we used a combination of observations and Weld experiments to determine the degree to which germination rates of the palm Astrocaryum mexicanum varied with abundance of a small mammal seed predator/disperser, Heteromys desmarestianus, in a lowland tropical forest. Patterns of abundance of the two species were strongly related; density of H. desmarestianus was low in sites with low density of A. mexicanum and vice versa. Rates of predation and dispersal of A. mexicanum seeds depended on abundance of H. desmarestianus; sites with high densities of H. desmarestianus had the highest rates of seed predation and lowest rates of seed germination, but a greater total number of seeds were dispersed and there was greater density of seedlings, saplings, and adults of A. mexicanum in these sites. When abundance of H. desmarestianus was experimentally reduced, rates of seed predation decreased, but so did dispersal of A. mexicanum seeds. Critically, rates of germination of dispersed seeds were 5 times greater than undispersed seeds. The results suggest that the relationship between A. mexicanum and H. desmarestianus is a conditional mutualism that results in a strong local eVect on the abundance of each species. However, the magnitude and direction of these eVects are determined by the relative strength of opposing, but related, mechanisms. A. mexicanum nuts provide H. desmarestianus with a critical food resource, and while seed predation on A. mexicanum nuts by H. desmarestianus is very intense, A. mexicanum ultimately beneWts because of the relatively high germination rates of its seeds that are dispersed by H. desmarestianus.

    Item Type: Peer-reviewed Journal Article
    Related URLs:
    Unique ID or DOI: 10.1007/s00442-009-1542-3
    Publisher: Springer Verlag
    Keywords: Granivory · Predation limitation · Recruitment limitation · Seed predation
    Subjects: (A) Biodiversity > (AH) Plants
    (Z) Other or Unspecified
    Publication Sources: (3) Other Source > (3C) Other Universities
    Date Deposited: 14 Dec 2010 15:44
    Last Modified: 20 Jan 2011 14:26
    URI: http://eprints.uberibz.org/id/eprint/1117

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