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Abstract Detail

Pollination Biology

Chang, Shumei [1].

Pollen competition in style: is there a pollen size-number trade off in the common morning glory?

Though it is well known that pollen size varies greatly among different angiosperm species, this trait is generally assumed to have little genetic variation within a species, presumably due to strong selection for the optimal size in each species. However, this assumption has been challenged by recent studies that revealed significant genetic variation of pollen size in natural populations of several species, highlighting the question of what maintains genetic variation in this important male fitness trait. Using an artificial selection approach, we generated selection lines of the common morning glory, Ipomoea purpurea, that diverged significantly in the average pollen size. From a previous study, we know that larger pollen grains are more competitive than smaller pollen grains during pollen competition when equal number of pollen grains were used in the hand-pollination experiment. However, whether similar patterns can be found during natural pollination remains unknown. Here, we investigate whether larger pollen grains still have the competitive advantage over smaller grains when plants are exposed to natural pollinators. Using plants from the selection lines in garden array studies, we estimate the relative siring success of large- and small-pollen plants. Our results show that while per-flower siring success supports our earlier finding of larger-pollen grains being more competitive, a size-number trade off at the plant level provides a potential mechanism for how pollen size variation might be maintained in natural populations of this species.

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1 - University Of Georgia, Plant Biology, 2502 Miller Plant Sciences, Athens, GA, 30602, USA

Pollen competition
Genetic variation
size-number trade off
pollen size.

Presentation Type: Oral Paper
Session: 36, Pollination Biology
Location: 203/Savannah International Trade and Convention Center
Date: Wednesday, August 3rd, 2016
Time: 9:00 AM
Number: 36005
Abstract ID:451
Candidate for Awards:None

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