Abstract
More than 300 isolates of the Irish potato famine fungus, Phytophthora infestans, collected in 20 countries on five continents, were analyzed for genetic variation at the mating type and two allozyme loci. A subset of more than 200 isolates was also analyzed for DNA "fingerprint" variation. A surprising result was that a single clonal lineage dominated most populations worldwide. All of the variation within this lineage appeared to have arisen by mitotic recombination or by mutation. In addition to the most common clonal lineage, a number of different, but apparently closely related, lineages occurred in the United States and Canada. The low levels of gene diversity in the derived populations compared to the presumed ancestral population in central Mexico indicate that P. infestans went through extreme genetic bottlenecks during its dispersal. The genetic data are consistent with the hypothesis that the initial migration of P. infestans in the 1840s was from Mexico to the United States and that only a single genetic individual was transported to Europe and subsequently to the rest of the world. If this hypothesis is correct, then the Irish potato famine was caused by a single clonal genotype of P. infestans.
Full text
PDF
Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Goodwin S. B., Drenth A., Fry W. E. Cloning and genetic analyses of two highly polymorphic, moderately repetitive nuclear DNAs from Phytophthora infestans. Curr Genet. 1992 Aug;22(2):107–115. doi: 10.1007/BF00351469. [DOI] [PubMed] [Google Scholar]
- Maruyama T., Fuerst P. A. Population bottlenecks and nonequilibrium models in population genetics. II. Number of alleles in a small population that was formed by a recent bottleneck. Genetics. 1985 Nov;111(3):675–689. doi: 10.1093/genetics/111.3.675. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nei M., Chesser R. K. Estimation of fixation indices and gene diversities. Ann Hum Genet. 1983 Jul;47(Pt 3):253–259. doi: 10.1111/j.1469-1809.1983.tb00993.x. [DOI] [PubMed] [Google Scholar]
- Taylor C. E. Population genetics of a "colonising" lizard: natural selection for allozyme morphs in Anolis grahami. Heredity (Edinb) 1975 Oct;35(2):241–247. doi: 10.1038/hdy.1975.88. [DOI] [PubMed] [Google Scholar]