Handbook Part 2 - International Mycological Association

PS8-458-0267
Population Biology Of The Sapstain Fungus, Ophiostoma ips, Reflects Global Movement Of Its Bark Beetle
Vectors
X.D. Zhou 1, T. Burgess 2, Z.W. de beer 3, F. Lieutier 4, A. Yart 5, K. Klepzig 6, A. Carnegie 7, J.M. Portales 8, B.D. Wingfield
9, M.J. Wingfield 10
1 Forestry and Agricultural Biotechnology Institute (FABI); University of Pretoria, Pretoria, South Africa, 2 Department of
Biological Sciences and Biotechnology, Murdoch University, Perth, Australia, 3 Department of Microbiology and Plant
Pathology, University of Pretoria, Pretoria, South Africa, 4 Laboratoire de Biologie des Ligneux et des Grandes Cultures,
Université d’Orléans, Rue de Chartres, B.P. 6759, 45067 Orleans Cedex 2, Orléans, France, 5 Institut National de la
Recherche Agronomique (INRA), Pathologie Forestiere, Champenoux, F-54280, Champenoux, France, 6 USDA Forest
Service, Southern Research Station, 2500 Shreveport Hwy, Pineville, 71360, LA, United States, 7 Forest Research
Development Division, State Forest of NSW, NSW, Australia, 8 Instituto de Ecología y Sistemática (IES), Agencia de
Medio Ambiente (AMA), Carretera de Varona km. 31/2, Capdevila, Boyeros, A.P.8029, C.P. 10800, Ciudad de La
Habana, Cuba, 9 Department of Genetics, University of Pretoria, Pretoria, South Africa, 10 Forestry and Agricultural
Biotechnology Institute (FABI); University of Pretoria, Pretoria, South Africa
Bark beetles commonly infest conifers and live in a close association with fungi, especially Ophiostoma species and
their anamorphs. Ophiostoma ips is a common fungal associate of various bark beetle species in their native ranges
and has been introduced into non-native pine plantations in the Southern Hemisphere. In this study, we consider the
population biology of O. ips in native and non-native areas to characterize host specificity, reproductive behavior, the
potential origin, and spread patterns of this fungus, together with its insect vectors. Ten pairs of Single Short Repeat
(SSR) markers were used to examine the structure of seven populations of O. ips including four native populations from
Cuba, France, Morocco and USA, and three introduced populations from Australia, Chile and South Africa. The SSR
markers across 10 loci examined resolved a total of 41 alleles and 93 genotypes across all populations. Higher genetic
diversity was found in the native populations than in the introduced populations. Most alleles were present in all native
populations although allele frequencies among populations varied. There was no evidence of specificity of the
fungus to particular bark beetle vectors and hosts. Although O. ips is homothallic, recombination occurred in the four
native populations surveyed. Genetic relatedness of the fungal isolates both from native and exotic environments
confirmed the origins of the fungus and its insect vectors. Most alleles observed in the native European population
were also found in the native North American population, and this could be due to multiple introductions of European
vectors to North America. The higher genetic diversity in the North American population than in the European
population suggests that North America would be the most probable source region of O. ips.
PS8-459-0275
Phylogeography, cryptic speciation and hybridization in the cellar fungus Coniophora puteana
I Bjorvand Svegården 1, N Hallenberg 3, C DeCock 2, H Kauserud 1
1 Department of Biology, University of Oslo, Oslo, Norway, 2 Mycothèque de l’Université Catholique de Louvain,
Faculté des Sciences Agronomiques, Louvain-la-Neuve, Belgium, 3 Systematic Botany, Botanical Institute, Göteborg
University, Göteborg, Sweden
Fungi often have complex and unpredictable population structures and phylogeographic patterns due to their highly
variable life history characteristics. The occurrence of unknown biological mating barriers adds an extra layer of
complexity to the analysis of genetic variation in fungi. In this study, we explored the genetic variation and
phylogeographic structure in a global sample of the cellar fungus Coniophora putana, which is an important
destroyer of wooden constructions indoor. DNA sequences were obtained from three independent nuclear DNA loci
(beta tubulin, nrDNA ITS and translation elongation factor). The genealogies revealed the occurrence of three
separate lineages in the morphotaxon C. puteana, apparently representing three cryptic species (PS1-PS3). One of
the lineages (PS3) seems to be restricted to North America while the other two have wider distributions, occurring on
different continents. In these two lineages (PS1 and PS2), there was little correspondence between genetic and
geographic separation, apparently reflecting high gene flow at intercontinental scales. Our data demonstrate that
the three lineages reproduce mainly by outcrossing. All three lineages occur in sympatry in North America and our
data indicate that hybridization and subsequent intralocus recombination, leading to mosaic sequences, have
occurred among two of the lineages in this region (PS1 and PS3). We hypothesize that these two lineages evolved in
allopatry earlier, succeeded by a more recent reoccurrence in sympatry, enabling reticulate evolution. Thus,
biological barriers to gene flow have apparently not yet evolved between two of the lineages. This study supports the
view that cryptic speciation is a very common phenomenon in fungi.
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