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Title:Sex, Diversity, and Differentiation Within and Between Populations of an Aquatic Hyphomycete
Author(s):Anderson, Jennifer Lynn
Doctoral Committee Chair(s):Carol A. Shearer; Weidong Chen
Department / Program:Plant Biology
Discipline:Plant Biology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Biology, Plant Physiology
Abstract:Aquatic hyphomycetes contribute to energy flow and nutrient spiraling in rivers by making energy and fixed carbon in autumn-shed leaves available to aquatic invertebrates. These fungi are haploid, predominantly or exclusively asexual, have restricted dispersal abilities, and experience yearly population bottlenecks as the amount of available substrate decreases in late summer; four factors that may limit the ability of populations of aquatic hyphomycetes to acquire and maintain genetic diversity. Tetracladium marchalianum is used in this study to answer three questions pertaining to the natural histories and evolutionary potential of these ecologically important fungi. (1) Is genetic recombination contributing to genotypic diversity of this fungus? (2) How is genotypic diversity distributed among populations of this fungus? (3) Is genotypic diversity changing over time as population size rises and falls seasonally? To answer these questions, polymorphic microsatellite and AFLP loci were identified for T. marchalianum and used to obtain multilocus haplotypes for use in population genetic analyses. Leaves from three sites on the Sangamon River (Illinois), three sites on the Middle Fork of the Vermilion River (Illinois), and one site on Konkapot Creek (Wisconsin) served as the sources of fungal cultures, each originating from a single asexually produced spore, allowing genotypic diversity and genetic differentiation to be assessed within each stream at different sites as well as between rivers from different watersheds. Collections were also made from one site on the Sangamon River repeatedly over two years, allowing analysis of genotypic diversity changes over time. Index of Association and Parsimony Tree Length Permutation Test analyses did not detect recombination in populations of T. marchalianum , providing evidence for clonality in this species. All Illinois sites, although spatially separated within rivers and between rivers in different watersheds, demonstrate no significant differentiation. Significant differentiation between populations was only observed between the most distant sites (Illinois vs. Wisconsin). Analyses of differentiation among collections from two years of collections on the Sangamon River do not indicate temporal population differentiation; therefore, if population bottlenecks are occurring annually, they are not dramatically altering the population genetics of this fungus.
Issue Date:2004
Description:169 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2004.
Other Identifier(s):(MiAaPQ)AAI3153236
Date Available in IDEALS:2015-09-28
Date Deposited:2004

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