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Abstract Detail


Ecological Section

Landry, Carol L. [1].

Pollinator visitation rate helps explain male frequency in androdioecious populations of Laguncularia racemosa.

Androdioecy is a rare breeding system with two breeding types, males and hermaphrodites. Theoretical models predict that males can only be maintained in populations with hermaphrodites if they have at least twice the fitness contributed by the male component of hermaphrodites. In wind-pollinated plant species, males can incur this fitness advantage through increased pollen production, particularly in populations with high outcrossing rates and strong inbreeding depression. However in animal-pollinated species, effective pollen fecundity is determined not only by pollen production but also by pollinator behavior. I added one aspect of pollinator behavior, relative pollinator visitation rate (hermaphrodite/male), to Lloyd’s model for the maintenance of androdioecy. The relative pollinator visitation rate parameter modifies intrinsic pollen fecundity (the amount of pollen produced), thereby more accurately describing the effective pollen fecundity in animal-pollinated species. Here I compare male frequency predictions generated by both Lloyd’s model and the new model with observed male frequencies in two androdioecious subpopulations of Laguncularia racemosa (Combretaceae; white mangrove). White mangrove is an insect-pollinated species visited primarily by wasps, bees, and flies. All model parameters (outcrossing rate, inbreeding depression, intrinsic pollen fecundity, and pollinator visitation rate) were estimated from pollination studies and pollinator observations. Because outcrossing rates were estimated from the length of pollinator foraging bouts within plants and pollen carryover assumptions, a range of outcrossing rates are considered for each subpopulation. The inclusion of relative pollinator visitation rates resulted in more accurate male frequency predictions from my model compared to Lloyd’s model for both subpopulations. Observed male frequencies fell within the range of frequencies predicted by my model but not Lloyd’s model. This comparison suggests that the impact of pollinator behavior on effective pollen fecundity and outcrossing rates should be considered when studying the factors responsible for the maintenance of androdioecy.


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1 - University of Michigan, Department of Ecology and Evolutionary Biology, Ann Arbor, MI, 48109, U.S.A.

Keywords:
androdioecy
pollinator behavior.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P49026
Abstract ID:1959


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