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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, vol. 30 , pp. 319-324 , doi: 10.1111/j.1442-9993.2005.01476.x.

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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
Authors/Creators:Hingston, AB and Potts, BM
Journal or Publication Title: Austral Ecology
ISSN: 1442-9985
DOI / ID Number: 10.1111/j.1442-9993.2005.01476.x
Additional Information:

BM Potts. The definitive version is available at

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