Professor; Ph.D., University of Utah
Address: Department of Botany, The University of Tennessee, Knoxville, TN 37996-1100; E-mail: khughes@utk.edu ; Telephone: 865 974-2256; Fax: 865 974-2258.
My current area of interest involves patterns of evolution and speciation with emphasis on fungi (mushrooms). These studies are a collaborative effort between Dr. Petersen's laboratory and my laboratory. Evolutionary processes are examined using several techniques. Enzyme profiles, mitochondrial restriction fragment patterns, ISSRs and nuclear restriction fragment length polymorphisms are used to define population structure, to assess gene flow between populations and to determine how species have evolved. PCR amplification of specific genes and DNA sequencing is used in order to obtain an estimate of older relationships between species. Fungal biogeographical patterns are inferred using morphology, mating studies, DNA sequencing and RFLP patterns. We have found that the same fungal species exist in Eurasia and North America however, there regions have been separated for long time periods, perhaps as long as 50 million years. Within North America, genetically distinct populations appear to be the result of expansion from refugia that existed during the last glacial period, 20,000 years ago.
See the Mycology Group Web Page for further Information
Petersen, R.H., D.B.G. Nicholl and K.W. Hughes. 1998. Mating systems of some putative polypore-agaric relatives. Plant Systematics and Evolution 207:135-158.
Petersen, R.H. and K.W. Hughes. 1998. A new species of Pleurotus. Mycologia 89(1):173-180.
Abstract: A new species of Pleurotus, P. abieticola, was collected in far eastern Russia. We show that Pleurotus abieticola is reproductively isolated from other Pleurotus species. Comparisons of ribosomal DNA-sequence data grouped P. abieticola with monomitic pleurotoid species of the genus, while cluster analysis (Neighbor Joining) and parsimony analysis indicated that P. abieticola was distinct from extant species. The combination of differences in morphology, reproductive isolation, substrate preference and DNA sequence justifies the proposal of a new species.
Hughes, K.W. and R.H. Petersen. 1998. Relationships between Omphalotus species based on RFLP patterns of the ribosomal ITSI-5.8S-ITS2 region. Plant Syst. Evol. 211: 231-237
Abstract: Genetic relationships for several species of the fungus Omphalotus were estimated by comparing the presence or absence of restriction sites in the ITS1-5.8S-ITS2 region of nuclear ribosomal DNA. Results place European O. olearius (Europe), O. subilludens (Florida)and O. olivascens (California) in a single clade. O. illudens (Tennessee), usually thought to be related to O. subilludens, was placed in a second clade, more closely related to O. nidiformis from Australia. O. mexicana is distinct from all other examined Omphalotus species
Petersen, R.H. and K.W. Hughes. 1998. Mating systems in Omphalotus (Paxillaceae, Agaricales). Syst. Evol. 211:217-229.
Hughes, K.W., T. Toyahara and R.H.Petersen (1998) Disjunct populations of Pleurotopsis longinqua. Mycologia 90 (4):595-600
Abstract:The known distribution of Pleurotopsis longinqua is restricted to southeastern Australia, New Zealand, Patagonia, and the northern Pacific coast of North America. Previous studies demonstrated that isolates from all of these areas were sexually compatible (i.e. were the same biological species). Intercompatibility studies, however, did not provide information about genetic (evolutionary) relationships among the disjunct populations. Restriction fragment patterns of the nuclear ribosomal ITS1-5.8S-ITS2 were compared for isolates from each geographical region to estimate genetic divergence. Only one enzyme, Taq I, discriminated between different collections. To further examine genetic divergence, the ITS1-5.8S-ITS2 region was sequenced for one collection from each geographical area. Only four base-pair differences were observed among isolates from New Zealand, Argentina and Washington State. The remarkable similarity of these collections suggests that the current disjunct distribution is not very old.
1999
Petersen, R.H., and K.W. Hughes.(1999) Species and speciation in mushrooms. BioScience 49 (6)440-452
Petersen, R.H., Hughes, K.W., Redhead, S.A., Psurtseva N. and Methven, A.S. (1999) Mating systems in the Xerulaceae (Agaricales, Basidiomycotina): Flammulina Mycoscience 40:411-426.
Hughes, K.W., McGhee, L. L., Methven, A.S., Johnson, J.E., Petersen, R.H. 1999. Patterns of geographic speciation in the genus Flammulina based in sequences of the ribosomal ITS1-5.8S-ITS2 area. Mycologia 96:978-986.
2000
Methven,
A., Hughes, K. and Petersen, R.H. (2000) Flammulina
velutipes RFLP patterns identify species and show biogeographical patterns
within species. Mycologia 92:1064-1070.
2001
Jin,
J.K., Hughes, K.W. and Petersen, R.H. 2001.
Biographical patterns in Panellus
stypticus. Mycologia 93
(2):308-315
Hughes,
K. W. and Petersen, R. H. (2001) Apparent hybridization, recombination and gene
conversion of the ribosomal DNA repeat in the mushroom
genus Flammulina. Mol. Biol.
Evol. 18:94-96.
Hughes,
K.W., Petersen, R.H., Johnson, J.E., Moncalvo, J.M., Vilgalys, R, Redhead, S.A.,
Thomas, T. and McGhee, L.L. (2001) Infrageneric phylogeny of Collybia
ss.str. based on sequences of ribosomal ITS and LSU regions. Mycological
Research 105 (2):164-172
Jin,
J. K., Hughes, K. W. and Petersen,
R. H. (2001). Phylogenetic
relationships of Panellus (Agariclaes) and related species based on morphology
and ribosomal large subunit DNA sequences.
Mycotaxon 79:7-21
Mata,
J. L., Petersen, R. H. and Hughes, K. W. (2001) The genus Lentinula in
the American continent. Mycologia
93 (6): 1102-1112
2002
 | POLYMERASE CHAIN REACTION: The polymerase chain reaction (PCR) is a procedure for amplifying a specific DNA fragment or gene from a DNA sample containing millions of genes. The basic elements of the process are diagramed to help students picture the process. |
| DNA SEQUENCING: DNA sequencing using dideoxy bases to terminate reactions is diagramed and photos of automated sequencing are shown. |
| GEL ELECTROPHORESIS: DNA and proteins may be separated by gel electrophoresis procedures. Separation of DNA fragments is presented in diagrams and photos. |