Document Detail

Expanding the limits of the pollen-limitation concept: effects of pollen quantity and quality.
MedLine Citation:
PMID:  17479745     Owner:  NLM     Status:  MEDLINE    
Pollination commonly limits seed production, as addition of pollen to stigmas often increases fecundity. This response is usually interpreted as evidence that plants' stigmas receive too few pollen grains to maximize ovule fertilization (quantity limitation); however, many genetic studies demonstrate that poor-quality pollen can also reduce seed production (quality limitation). We explore both aspects of pollen limitation theoretically with a dose-response model that incorporates a saturating negative-exponential relation of seed production to pollen receipt. This relation depends on aspects of ovule production, pollen import, pollen-pistil interactions and seed development, all of which can contribute to pollen limitation. Our model reveals that quantity limitation is restricted to the lowest range of pollen receipt, for which siring success per pollen grain is high, whereas quality limitation acts throughout the range of pollen receipt if plants do not import the highest-quality pollen. In addition to pollinator availability and efficiency, quantity limitation is governed by all post-pollination aspects of seed production. In contrast, quality limitation depends on the difference in survival of embryos sired by naturally delivered pollen vs. by pollen of maximal quality. We briefly illustrate the distinction between these two components of pollen limitation with results from the mistletoe Tristerix corymbosus. Our model also shows that the standard pollen-supplementation technique neither estimates the total intensity of pollen limitation nor distinguishes between its quantity and quality components. As an alternative, we propose a methodological protocol that requires both measurement of seed production following excess pollination with only outcross pollen and quantification of the dose-response relation of seed output to pollen receipt. This method estimates both the total extent of pollen limitation and its two components. Finally, we consider the influences on quantity and quality limitation, which reveals that quantity limitation probably occurs much less often than has been inferred from pollen-supplementation experiments. These interpretations suggest that an expanded perspective that recognizes the fecundity consequences of pollination with poor-quality pollen would promote ecological understanding of pollen limitation.
Marcelo A Aizen; Lawrence D Harder
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Ecology     Volume:  88     ISSN:  0012-9658     ISO Abbreviation:  Ecology     Publication Date:  2007 Feb 
Date Detail:
Created Date:  2007-05-07     Completed Date:  2007-06-19     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0043541     Medline TA:  Ecology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  271-81     Citation Subset:  IM    
Laboratorio Ecotono, Universidad Nacional del Comahue, Centro Regional Bariloche, Quintral 1250, 8400 San Carlos de Bariloche, Rio Negro, Argentina.
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MeSH Terms
Angiosperms / physiology*
Models, Biological
Pollen / physiology*
Reproduction / physiology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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