Evol Ecol Res 6: 1237-1252 (2004)     Full PDF if your library subscribes.

Whole-plant investment in nectar is greater for males than pollinated females in the dioecious plant Silene latifolia

Janet L. Gehring,1* Jennifer Scoby,1 Michael Parsons1 and Lynda F. Delph2

1Department of Biology, Bradley University, 1501 W. Bradley Avenue, Peoria, IL 61625 and  2Department of Biology, Indiana University, Jordan Hall, Bloomington, IN 47405, USA

Author to whom all correspondence should be addressed.
e-mail: jgehring@bumail.bradley.edu


Sexual dimorphism in nectar traits can contribute to sex-differential costs of reproduction in dioecious plants. We examined nectar traits of males and females in paternal half-sibling families of dioecious Silene latifolia, a species with sexually dimorphic flower production that is pollinated by nectar-seeking moths. Nectar volume and total sugar content peaked 3 days after flower opening in males and 4 days after flower opening in females. Flowers on females had greater nectar volume and total sugar than did those on males, but nectar in the latter was higher in concentration. Variation among paternal families in nectar volume and total sugar was detected only in females; selection by pollinators may have eliminated genetic variation in nectar production in males. We estimated whole-plant investment in nectar by multiplying family means by the number of reproductive units of each plant. Nectar investment per plant did not differ between males and unpollinated females, but was much lower in pollinated females because they produced fewer flowers. Based on estimated values of flower and fruit number, whole-plant nectar investment for males is expected to be higher than that for females under low to moderate levels of pollination.

Keywords: cost of reproduction, dioecy, nectar, sexual dimorphism.

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        © 2004 Janet L. Gehring. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

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