Present address: Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Clonal population structure of the chestnut blight fungus in expanding ranges in southeastern Europe
Article first published online: 18 SEP 2008
© 2008 The Authors. Journal compilation © 2008 Blackwell Publishing Ltd
Volume 17, Issue 20, pages 4446–4458, October 2008
How to Cite
MILGROOM, M. G., SOTIROVSKI, K., SPICA, D., DAVIS, J. E., BREWER, M. T., MILEV, M. and CORTESI, P. (2008), Clonal population structure of the chestnut blight fungus in expanding ranges in southeastern Europe. Molecular Ecology, 17: 4446–4458. doi: 10.1111/j.1365-294X.2008.03927.x
- Issue published online: 9 OCT 2008
- Article first published online: 18 SEP 2008
- Received 11 June 2008; revision received 24 July 2008; accepted 2 August 2008
- chestnut blight fungus;
- clonal population;
- Cryphonectria parasitica;
- marginal populations;
- population structure;
Expanding populations are often less genetically diverse at their margins than at the centre of a species’ range. Established, older populations of the chestnut blight fungus, Cryphonectria parasitica, are more variable for vegetative compatibility (vc) types than in expanding populations in southeastern Europe where C. parasitica has colonized relatively recently. To test whether vc types represent clones, we genotyped 373 isolates of C. parasitica from southern Italy, Romania, Bulgaria, Macedonia, Greece and Turkey using 11 sequence-characterized amplified region (SCAR) markers. Ten SCAR loci and six vegetative incompatibility (vic) loci were polymorphic in these samples. These populations are clonal by all criteria tested: (i) among 373 isolates, we found only eight multilocus haplotypes, and the same haplotypes were found in multiple countries, sometimes separated in time by as much as 12 years; (ii) the number of haplotypes observed was significantly less than expected under random mating; (iii) populations are in linkage disequilibrium; (iv) the two sets of independent markers, SCARs and vc types, are highly correlated; and (v) sexual structures of C. parasitica were found only in Bulgaria and Romania. One mating type (MAT-1) was found in 98% of the isolates sampled. In contrast, a population in northern Italy, in the central part of the range in Europe, had 12 multilocus haplotypes among 19 isolates. The spread of a few clones could be the result either of founder effect and restricted migration, or these clones have greater fitness than others and spread because they are better adapted to conditions in southeastern Europe.