Doctoral Dissertations

Date of Award

8-1994

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Botany

Major Professor

Ronald H. Peterson

Committee Members

Sally Horn, Karen W. Hughes, Edward Schilling

Abstract

The litter-binding and litter-decomposing genus Marasmius consists of approximately 500 species epithets worldwide. Species concepts in this genus are based on traditional morphological criteria. Examination of additional character suites, and analysis of correlation of these characters, can permit a better assessment of infraspecific diversity and aid in formulation of more cohesive species concepts. This study used North American and European collections/cultures of Marasmius androsaceus, Marasmius rotula, and Marasmius scorodonius to: 1) provide detailed morphological analysis of all appropriate collections of each taxon; 2) employ monokaryotic cultures of European and North American collections to test intra- and intercontinental mating compatibility; 3) use enzyme electrophoresis to assess enzyme profiles; and 4) compare and correlate the above data sets to provide information on infraspecific variation of each species and possible differential evolution of these characters, thereby attaining more comprehensive views of species concepts, speciation, and speciation processes in these fungi. Marasmius androsaceus shows incongruency between morphological and biological species concepts. Collections of M. androsaceus show congruency in morphology but this morphological species consists of at least three biological species. Collections of M. rotula show congruency between morphological and biological species concepts. It is apparent however, that genetic divergence between allopatric populations (Europe vs. North America) has resulted in reduced mating compatibility. Marasmius scorodonius shows congruency between morphological and biological species concepts. Depending on which enzyme system is analyzed, each taxon shows differing levels of variation which in some cases correlates with biological species concepts and/or geography. Examination of individual character suites and correlation of these character suites is discussed in regards to speciation and species concepts in these fungi.

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