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| Title: | MAINTENANCE OF SEXUALLY DIMORPHIC PATTERNS OF GROWTH AND REPRODUCTION IN MARCHANTIA INFLEXA |
| Authors: | Fuselier, Linda Catherine |
| Keywords: | Bryophyte
sexual dimorphism
selection
plasticity
liverwort |
| Date Created: | 2004 |
| Publisher: | University of Kentucky |
| Abstract: | Sexual dimorphism in life history traits may influence the distribution of the sexes,
population sex ratios, the maintenance of sex in populations, and the evolutionary
potential of a species. In bryophytes, sexual dimorphism in traits related to growth and
reproduction may be responsible for female-biased population sex ratios and a lack of
sexual reproduction. I examined the roles of natural selection in maintaining sexual
dimorphism in the context of impacts on bryophyte population sex ratios, using
Marchantia inflexa as a model system. My studies included an assessment of amongpopulation
variation in habitat use by the sexes, comparison of phenotypes between
single-sex and both-sex populations, a field study of natural selection, and a comparison
of the influence of selection on asexual and sexual fitness components.
The sexes of M. inflexa were sexually dimorphic in investment in growth, asexual
and sexual reproduction. The sexes were spatially separated in populations, but the
sexes overlapped in habitat use. Populations differed in growth, asexual reproduction
rates, degrees of sexual dimorphism, and strength of among-trait correlations. Plants
from single-sex and both-sex populations differed in investment in growth and asexual
reproduction, but the two population types showed the same degree of sexual
dimorphism. Thus, local environment may be more influential than the presence of the
opposite sex in maintaining sexual dimorphism.
Selection on sexually dimorphic traits was both sex-specific and environmentally
dependent. Between-sex correlations were not significant in the greenhouse but were
significant in the field thus, evolution and expression of sexual dimorphism in nature may
be constrained by among-trait and between-sex correlations. Additionally, females
incurred a cost of plasticity that males did not. Because there was a negative trade-off
between sexual and asexual fitness, overall lifetime selection may result in a different
picture of how the sexes experience selection. The combination of sex-specific and
environment-dependent selection, and sex-specific costs to plasticity may not only
maintain sexually dimorphic traits but also ensure the persistence of both sexes in a
population. |
| URI: | http://hdl.handle.net/10225/138 |
| Appears in Collections: | Electronic Theses and Dissertations
|
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| File |
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Size | Format |
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| fuselier.pdf | | 833Kb | Adobe PDF | View/Open |
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