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Sexual dimorphism in bryophytes: Patterns and consequences

Fuselier, Linda [1].

Sex-specific and environment-dependent selection influence sexual dimorphism and the distribution of sexes of a thallose liverwort.

Sexual dimorphism may evolve and be maintained when natural selection favors different phenotypic trait optima for the sexes. Additionally, selection acting differently in different environments may promote phenotypic and genetic variation within populations and influence the distribution of plants. Because many species of liverworts are dioicous and many dioicous taxa exhibit disjunct distributions of the sexes, I examined whether sex-specific &/or environment-dependent selection influenced the maintenance of sexual dimorphism and the distribution of sexes in a dioicous liverwort. Replicate genotypes of Marchantia inflexa, a thallose liverwort, were planted under four light/moisture treatments at a field site where the species historically occurred. Sex-specific and environment-dependent genotypic selection was measured on the sexes in each environment and fitness maxima for the sexes were compared graphically. Selection was both sex-specific and environment-dependent, and patterns of sex-specific selection differed across environments. Selection differed in strength, direction and type between the sexes among treatments. Selection favored larger plants that produced more asexual propagules and, overall, selection was stronger on males than females. Selection was environment-dependent on females across moisture, and males across moisture and light treatments. The combination of sex-specific and environment-dependent selection may promote phenotypic variation and the persistence of both sexes in populations dioicous liverworts.


1 - University of Kentucky, Department of Biology, 101 Morgan Bldg, Lexington, Kentucky, 40506, USA

Keywords:
sex dimorphism
bryophyte
natural selection.

Presentation Type: Symposium
Session: 27-4
Location: Ballroom 3 (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 9:45 AM
Abstract ID:104


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