Evol Ecol Res 10: 61-75 (2008)     Full PDF if your library subscribes.

A test of the differential-plasticity hypothesis for variation in the degree of sexual dimorphism in Silene latifolia

Lynda F. Delph* and Daniela L. Bell

Department of Biology, Indiana University, 1001 East Third Street, Bloomington, IN 47405-3700, USA

Author to whom all correspondence should be addressed.
e-mail: ldelph@indiana.edu


Questions: Is there variation in the degree of sexual dimorphism among populations? Do males exhibit more (or less) plasticity than females?

Hypothesis: Among-population variation in the degree of sexual dimorphism is caused by sex-differential plasticity.

Organism: Silene latifolia, a dioecious plant that exhibits sexual dimorphism in many traits.

Methods: We grew individuals from three populations in a common greenhouse environment under two different (dry vs. wet) watering regimes. We measured ten traits at specific developmental points.

Results: Most traits showed significant among-population differentiation in their means and significant sexual dimorphism; however, population differentiation in the degree of sexual dimorphism was only observed for calyx width. Furthermore, differences between the sexes in their plastic responses were not observed for any trait. Hence, sex-differential plasticity to water is not the cause of differences among populations in the degree of sexual dimorphism in calyx width. Males varied less for this trait than females, suggesting that calyx width (or a trait correlated with calyx width) affects male fitness more than female fitness.

Keywords: common garden, differential-plasticity hypothesis, dioecious, phenotypic plasticity, physiology, sexual dimorphism.

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        © 2008 Lynda F. Delph. 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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