LAWREY, JAMES D.1*, PAUL DIEDERICH2, and PAULA T. DEPRIEST3. 1Department of Biology, George Mason University, Fairfax, VA 22030, U.S.A.; 2National Natural History Museum, 25 rue Munster, L-2160 Luxembourg, Luxembourg; 3Department of Botany, NHB-166, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, U.S.A.. - Genetic differentiation among populations of the widespread lichenicolous fungus Marchandiomyces corallinus.
The lichenicolous basidiomycete fungus Marchandiomyces corallinus is
widely distributed in North America and Europe. Unlike most
lichenicolous fungi, M. corallinus attacks numerous host lichens.
Theoretically, either of these characteristics, a wide geographic
range or generalized host ecology, could provide ample opportunities
for genetic differentiation within this species. To determine how
genetic variation is partitioned in M. corallinus, fungi were isolated
from several locations in North America and Europe, and also from
different lichen hosts in one of these locations; levels of genetic
differentiation were then estimated among these samples. Samples were
obtained from four sites in North America (Arkansas, Missouri,
Maryland, Virginia) and two in Europe (Ireland and Scotland). At a
single site (Scotland), samples were obtained from three different
lichen hosts. All isolates were used in vegetative mycelial
compatibility tests, which provide evidence of genetic identity. In
addition, a variety of nucleotide sequences from both nuclear and
mitochondrial ribosomal genes were obtained for each isolate. Mycelial
compatibility groups were recognizable based on geography, not the
choice of lichen host. Sequence data tended to confirm this result;
sequence differences among populations, where they existed at all,
were observed among geographically distant populations, not different
lichen hosts from the same site. These results suggest that genetic
differentiation among populations of M. corallinus have developed as a
consequence of geographic isolation, not host-switching.
Key words: basidiomycetes, lichenicolous fungi, lichens, Marchandiomyces corallinus