Document: JEN-3-44-10

Advantage to long-distance pollination in Leuhea seemannii, a tropical pioneer tree.

DAVIDSON, J.M.*

University of California, Davis, CA 95616 USA ¹

Abstract:
Paternity analyses for tropical trees show evidence of significant long distance gene flow ( 500 m), yet studies on pollinator movement indicate pollinators move most commonly between flowers on a given tree and then to nearest neighbor trees. What accounts for the difference in observed pollen movement over short distances versus fertilization success over long distances in tropical trees? I performed artificial crosses with pollen from near (< 100m) and far donors (> 2km) on seven Luehea seemannii trees within the Barro Colorado Nature Monument in Panama, to test for fitness differences in these two pollen sources in terms of seed capsule maturation, seed number/capsule, seed weight/capsule, seed resistance to soil pathogens during dormancy, and seedling growth. Pollen from far donors resulted in a significantly higher proportion of capsule maturation than pollen from near donors, translating into approximately 20% more seeds produced by far crosses than near crosses. Other measures of fitness did not differ significantly between the two pollen sources. Luehea is self-incompatible and has wind-dispersed seeds that form seed banks around parent trees and then germinate in light gaps. This dispersal syndrome may lead to higher levels of genetic relatedness among near-neighbors as opposed to distant adults, resulting in greater incompatibility or early-acting inbreeding due to near crosses, and an advantage to long-distance pollination for the onset of seed development.

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This abstract is being presented at: 8:00 AM in session:
Oral Session #6: Pollination Ecology.