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Oecologia

, Volume 137, Issue 1, pp 69–75 | Cite as

Sexual allocation in single-flowered hermaphroditic individuals in relation to plant and flower size

  • Marcos MéndezEmail author
  • Anna Traveset
Population Ecology

Abstract

Gender expression in hermaphroditic plant species usually departs from strict equisexuality. Study of those departures can aid understanding of non hermaphroditic breeding systems and prevalence of hermaphroditism within angiosperms. Plant size is one of the most studied factors in relation to gender modification. We studied variation in gender expression in the hermaphroditic, mostly single-flowered Paeonia cambessedesii. We separately studied gender modification with increasing plant and flower size using a variety of currencies: number of ovules and stamens, dry mass, N and P. Flower size and number of floral structures (petals, stamens, carpels, and ovules) increased with plant size. Number of ovules increased more rapidly with increasing plant size than number of stamens, indicating a bias towards femaleness with increasing plant size. A similar pattern was found when regressing number of stamens and number of seeds against plant size. Number of floral structures increased with increasing flower mass, but no significant difference was found between stamens and ovules in their rate of increase. Thus, gender modification at plant level was not consistent with patterns at flower level. No differential allocation to stamens vs gynoecium, or sexual structures vs petals was found when using dry mass, N or P as currencies. However, a disproportionate increase in female allocation was found when number of structures was utilised as currency. Study of size-dependent gender expression will benefit from contrast of results obtained using several analysis levels and allocation currencies.

Keywords

Allocation currency Ovule packaging Size-dependent sex allocation 

Notes

Acknowledgements

We thank Elena Portellano and Javier Rodríguez for their help during field and lab work, Enric Descals for providing facilities for the lab work at Mallorca, Rocío Requerey for pollen counts, P. Staffan Karlsson and the Abisko Scientific Research Station for providing facilities to perform the nutrient analyses, and Alfonso Sánchez-Lafuente and two anonymous referees for comments on the manuscript. M.M. was funded by a post-doctorate FPI grant from the Ministerio de Educación y Cultura (Spain). This work is framed within project PB97-1174 financed to A.T.

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Copyright information

© Springer-Verlag 2003

Authors and Affiliations

  1. 1.Department of Plant Ecology-Evolutionary Biology CentreUppsala University UppsalaSweden
  2. 2.Institut Mediterrani d'Estudis Avançats (C.S.I.C.-U.I.B.) EsporlesSpain
  3. 3.Botanical InstituteStockholm University StockholmSweden

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