HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

First published online April 13, 2009; doi:10.3732/ajb.0800039 American Journal of Botany 96: 968-978 (2009) © 2009 Botanical Society of America, Inc.

What's this?

This Article Full Text Full Text (PDF) Supplementary Data All Versions of this Article: ajb.0800039v1 96/5/968    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Delesalle, V. A. Articles by Mazer, S. J. Search for Related Content PubMed Articles by Delesalle, V. A. Articles by Mazer, S. J. Agricola Articles by Delesalle, V. A. Articles by Mazer, S. J. Social Bookmarking                            What's this?

Size-dependent pollen:ovule ratios and the allometry of floral sex allocation in Clarkia (Onagraceae) taxa with contrasting mating systems¹

² Department of Biology, Gettysburg College, Gettysburg, Pennsylvania 17325 USA ³ Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, California 93106 USA

ABSTRACT

Multiple field populations of two pairs of diploid sister taxa with contrasting mating systems in the genus Clarkia (Onagraceae) were surveyed to test predictions concerning the effects of resource status, estimated as plant size, on pollen and ovule production and on the pollen:ovule (P:O) ratio of flowers. Most theoretical models of size-dependent sex allocation predict that, in outcrossing populations, larger plants should allocate more resources to female function. Lower P:O ratios in larger plants compared to smaller plants have been interpreted as supporting this prediction. In contrast, we predicted that P:O ratio should not vary with plant size in predominantly selfing plants, in which each flower contributes to reproductive success equally through male and female function. We found that, in all four taxa, both ovule and pollen production per flower usually increased significantly with plant size and that the shape of this relationship was decelerating. However, ovule production either decelerated more rapidly than or at the same rate as pollen production with plant size. Consequently,the P:O ratio increased or had no relationship with plant size. This relationship was population-specific (not taxon-specific) and independent of the mating system. Possible explanations for the increasing maleness with plant size are discussed.

Key Words: Clarkia • gametophyte production • mating system • Onagraceae • pollen to ovule ratio • size-dependent sex allocation

Received for publication 31 January 2008. Accepted for publication 16 January 2009.

FOOTNOTES

¹ This work was supported by grants from the National Science Foundation (DEB 9816256 to V.A.D. and 9815300 to S.J.M.) and from Gettysburg College. A number of Gettysburg undergraduates (J. Knies, N. Alden, D. Campion, T. Kearins, J. Hoffman, J. LaPaglia) and M. Camara helped with data collection. V.A.D. also thanks M. Dudash and C. Fenster for hosting her in their laboratory during preparation of this manuscript. The authors also thank the reviewers and associate editor for comments that greatly improved this manuscript.

⁴ Author for correspondence (e-mail: delesall{at}gettysburg.edu)

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?