Evolutionary biology of the Armillaria mellea species complex

DNA-DNA hybridization experiments were used to examine the genetic variation that has accumulated with the North American Biological Species (NABS) of Armillaria. Forty strains including nine of the ten NABS and A. tabescens were used in this study. The normalized percent hybridization values ranged from 80%-100% similarity within a given biological species and ranged from 30%-85% among the biological species, The NPH data was summarized with UPGMA clustering analysis to give four main clustering groups, two were homogeneous and two were heterogeneous, The first included A. tabescens; the second included A. mellea; the third included A. calvescens, A. gallica, A. sinapina, NABS IX, and NABS X; the fourth included A. gemina and A. ostoyae. One cluster of two A. gallica strains shared greater similarity with NABS X than it had to four other conspecific strains, The NPH data and estimates of genome size (genetic complexity) was analyzed using a stoichiometric approach to calculate equivalents of homologous DNA and low copy repetition frequencies. Reciprocal NPH values did not predict relative genome size as expected, However, as the relative genome size increases, the equivalents of homologous DNA increases in the same proportion. This suggests that as an Armillaria genome increases in total complexity (novel sequences), certain ancestral sequences are duplicated in proportion the increase in total genetic complexity, This interpretation of the data is discussed with respect to interspecific hybridization, diploidy, and chromosomal evolution including alloploidy, aneuploidy, and chromosomal length polymorphisms.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Botany

Department dc:contributor.department

Botany

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1994

Author dc:creator

• Flynn, Timothy M.

Chairs dc:contributor.committeechair

• Vilgalys, Rytas J.
• Falkinham, Joseph O. III

Committee members dc:contributor.committeemember

• Niehaus, Walter G. Jr.
• Johnson, John S.
• West, David A.
• Stipes, R. Jay

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-10242005-124126

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/40131