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Bryological and Lichenological Section/ABLS

Jackson, Heather B [1], St. Clair, Larry L. [1].

Geographic parthenogenesis within facultatively sexual species?.

While the mystery surrounding the evolution of sex has been discussed since the early 1970ís, evolution of sex as it applies to fungi is a fairly recent discussion. Though geographic parthenogenesis, a pattern in which the range of asexual taxa tends to extend to higher latitudes and/or higher elevations than the range of their closely related sister sexual taxa, has been observed between species, little has been done to describe the variable distribution of sexual reproduction within facultatively sexual species. In this study we research the following overall question: Do populations of the lichenized fungus, Xanthoparmelia cumberlandia, favor an asexual strategy at higher latitudes and/or elevations? We have gathered observational data concerning the morphological differences between low and high elevation populations of X. cumberlandia which can be used to infer frequency of sexual reproduction. Comparisons between upper and lower elevations include proportion of the population bearing apothecia (sexual structures), percent area per thallus (body) allocated to apothecia, ascospores (sexual spores) per ascus, population size-structure, and chemotype diversity. We expect to find that apothecia production is increased, that ascospores are more fully developed, and that size and chemotype are more variable at the lower elevation, thus indicating more sexual reproduction. As a comprehensive study that notes multiple indicators of sexual outcrossing, this study will either support or detract from the common explanations for geographic parthenogenesis. This research will lend direction to further research which could use genetic data as well as density measurements of predators, parasites, and competitors to further elucidate the questions of where and why sex is adaptive.


1 - Brigham Young University, Department of Integrative Biology, P.O. Box 5181, Provo, Utah, 84602, USA

Keywords:
Evolution
geographic variation
lichen
sexual reproduction
fitness
fecundity
elevation.

Presentation Type: Paper
Session: 47-2
Location: Magpie (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 8:45 AM
Abstract ID:620


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