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Pollinator activity can explain variation in outcrossing rates within individual trees


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Hingston, AB and Potts, BM (2005) Pollinator activity can explain variation in outcrossing rates within individual trees. Austral Ecology, 30. pp. 319-324. ISSN 1442-9985

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We tested the hypothesis that the previously recorded higher outcrossing rates and numbers of seeds per capsule from the upper, than from the lower, branches of trees of Eucalyptus globulus (Myrtaceae) is the result of greater pollinator activity in the upper parts of the canopy. Observations of bird pollinators on 23 trees, with flowers distributed evenly between the upper and lower halves of canopies, supported this hypothesis. Birds spent significantly more time foraging, and commenced foraging significantly more often, in the upper halves than in the lower halves of canopies. Flowers in the upper halves of E. globulus canopies would therefore be expected to receive more outcross-pollen from bird pollinators because they are usually visited more often and would probably receive a greater ratio of outcross- to self-pollen. We propose that such variation in pollinator activity and outcrosspollen deposition results in different selective pressures on the mating system and pollination syndrome in different parts of the canopy. This may result in balanced selection for these traits, contributing to the maintenance of the mixed mating and generalized pollination systems of E. globulus.

Item Type: Article
Journal or Publication Title: Austral Ecology
Page Range: pp. 319-324
ISSN: 1442-9985
Identification Number - DOI: 10.1111/j.1442-9993.2005.01476.x
Additional Information: BM Potts. The definitive version is available at
Date Deposited: 05 Mar 2008 01:35
Last Modified: 18 Nov 2014 03:31
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