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Destination-based seed dispersal homogenizes genetic structure of a tropical palm

Authors

  • JORDAN KARUBIAN,

    1. Center for Tropical Research, Institute of the Environment, University of California, La Kretz Hall, Suite 300, Box 951496, Los Angeles, CA 90095, USA
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    • Present Address: Department of Ecology and Evolutionary Biology, Tulane University, 400 Lindy Boggs Center, New Orleans, LA 70118-5698, USA.

  • VICTORIA L. SORK,

    1. Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095-1606, USA
    2. Institute of the Environment, University of California, La Kretz Hall, Suite 300, Box 951496, Los Angeles, CA 90095, USA
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  • TESSA ROORDA,

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    • Present Address: Department of Ecology and Evolutionary Biology, Tulane University, 400 Lindy Boggs Center, New Orleans, LA 70118-5698, USA.

  • RENATA DURÃES,

    1. Center for Tropical Research, Institute of the Environment, University of California, La Kretz Hall, Suite 300, Box 951496, Los Angeles, CA 90095, USA
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  • THOMAS B. SMITH

    1. Center for Tropical Research, Institute of the Environment, University of California, La Kretz Hall, Suite 300, Box 951496, Los Angeles, CA 90095, USA
    2. Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095-1606, USA
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Jordan Karubian, Fax: (504) 862-8706; E-mail: jk@tulane.edu

Abstract

As the dominant seed dispersal agents in many ecosystems, frugivorous animals profoundly impact gene movement and fine-scale genetic structure of plants. Most frugivores engage in some form of destination-based dispersal, in that they move seeds towards specific destinations, resulting in clumped distributions of seeds away from the source tree. Molecular analyses of dispersed seeds and seedlings suggest that destination-based dispersal may often yield clusters of maternal genotypes and lead to pronounced local genetic structure. The long-wattled umbrellabird Cephalopterus penduliger is a frugivorous bird whose lek mating system creates a species-specific pattern of seed dispersal that can potentially be distinguished from background dispersal processes. We used this system to test how destination-based dispersal by umbrellabirds into the lek affects gene movement and genetic structure of one of their preferred food sources Oenocarpus bataua, a canopy palm tree. Relative to background dispersal processes, umbrellabird mating behaviour yielded more diverse seed pools in leks that included on average five times more seed sources and a higher incidence of long-distance dispersal events. This resulted in markedly lower fine-scale spatial genetic structure among established seedlings in leks than background areas. These species-specific impacts of destination-based dispersal illustrate how detailed knowledge of disperser behaviour can elucidate the mechanistic link driving observed patterns of seed movement and genetic structure.

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